High Protein Diets

High Protein Diets

For most of my adult life I’ve eaten high protein diets.

Throughout high school, college, and dental school – times when body composition was my primary focus – it was clear that eating protein way above RDA guidelines was the way to build muscle, stay lean, and obtain the body composition I desired.

During this time I heard all the typical fears around “eating too much protein.”

Too much protein will damage your kidneys, liver, and give you gout.

The acid load will leach calcium out of your bones.

Too much protein just turns to sugar anyway (GNG) and it elevates cortisol.

It will age you faster (mTOR, IGF-1) and decrease your life expectancy

The concerns go on and on.

Because fears around protein are so prevalent, I decided to write this post on protein “backwards” and start by addressing these fears.

The 1st half of this post will address 6 of the most common fears around eating high protein diets.

The 2nd half of this post will discuss why, instead of fearing protein, you should perhaps consider eating a high protein diet.

While this is a long post, for those that make it to the end, you’ll be equipped with more knowledge than most dietitians and even doctors about the most important macronutrient. But more importantly you’ll be equipped with a powerful tool in your toolbox to transform your health.

High Protein Diets: Table of Contents

Part 1: Dangers of High Protein Diets

• “Excess Protein” and Gluconeogenesis (GNG)
  • This is the #1 fear around protein, and this will be the #1 hardest section to get through. Please don’t get bogged down in the science if that’s not for you, just push on through it.
• HighProtein Diets and Gout
  • “Won’t eating too much meat give me gout?”
• HighProtein Diets and Kidney Health
  • “Isn’t too much protein hard on the kidneys?”
• HighProtein Diets and Bone Health
  • “Isn’t meat acidic?”
• HighProtein Diets and Longevity
  • “Doesn’t too much protein stimulate mTOR and IGF-1 and shorten lifespan?”
    • In this section I discuss something that I haven’t heard many people talk about, which I think may be the most important thing in the whole article: anabolism vs catabolism
      • If you read nothing else – read this section.
• Meat-based HighProtein Diets (Carnivore Diet) and Amino Acid Balances
  • “Won’t eating too much (muscle) meat get my amino acids “out of balance.”
    • Methionine vs Glycine (and more…)

Part 2: Protein — The Most Essential Macronutrient

• The Most Essential Macronutrient
  • Protein Malnutrition
• Protein Leverage Hypothesis
  • The key to solving obesity and disease prevention?
  • The most satiating macronutrient?
• High Protein Diets And Body Composition
  • The Most Overlooked Aspect of Fat Loss
  • The Protein Advantage
  • Fasting and Body Composition (warning and pitfalls)
  • Building Muscle without Putting on Excess Fat
  • Fat Loss and Muscle Building—beyond vanity
• HighProtein Diets: Plants vs Animals
  • Complete vs Incomplete Proteins
  • Protein Quality: DIASS
  • Cooked vs Raw
    • Denaturing of proteins
• HighProtein Diets: Final Thoughts
  • Do we need to revise the RDA on protein?
  • How much protein should you eat?

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Part 1: Dangers of High Protein Diets

#1: “Excess” Protein and Gluconeogenesis (GNG)

I would say the #1 fear / question I get about protein is:

Doesn’t Too Much Steak = Cake?

This fear is especially pronounced among ketogenic dieters where too much protein can kick you out of ketosis, or people with underlying blood sugar issues (i.e. pre/diabetes/hyperinsulinemia) where too much protein can raise blood glucose.

The argument goes something like this: You can’t store protein like you can carbs (glycogen) and fat (adipose), so if you eat more protein than the body can use it gets converted to sugar (glucose). Might as well eat cake!

To adequately address this fear this section is going to be the most “complex,” but hopefully the rest of the article is easier to digest. However, this foundational understanding of protein metabolism will be useful in understanding all the other issues surrounding around protein.

Protein Pathways

When you eat protein it gets broken down into amino acids which are absorbed into the body via amino acid transporters.

The gut itself will use a lot of these amino acids, especially those found in animal foods, like glutamate, glutamine, BCAAs, threonine, cysteine, and arginine. (r)

Is it really a wonder why so many people are healing their guts on a meat-based / carnivore diet? 

The small intestines can “hold on” to protein creating part of what is called the “amino acid pool,” which is the limited store of amino acids that the body can draw on in an as-needed basis. (r, r)

And because the digestion of protein (animal food in particular) is slow you can eat a whole lot of protein in one sitting.

30g Protein per Meal Myth

There is this thought that has spread around the web that you can only absorb 30g of protein at once.

Luckily, there is a study that highlights this absurdity. The researches had women eat 50g of protein in 1 meal vs over the course of 4 different meals. There was no difference in the amount of protein absorbed.

The myth that you can only absorb 30g of protein per sitting simply isn’t rooted in science nor supported by research. (r, r)

300g Protein per Day

Accompanying the myth that you can only absorb 30g protein per meal is a fear that even if you can absorb more, “excess” protein just turns to sugar (glucose) and ultimately gets stored as fat.

But before we start talking about “excess” protein, it’s important to know that protein is critical for countless processes.

Protein builds and repairs our bones, ligaments, connective tissue, hair, and nails. Not to mention our muscles. Proteins make antibodies and neurotransmitters. They make hormones and enzymes for everything from digestion to regulation of inflammation, to running our cells and maintaining all of our organs and tissues.

The fear of inadequate protein should trump the fear of “excess” protein. Skimping on protein is skimping on these vital functions.

But protein doesn’t stop there, it’s versatile enough to be used as energy, and this is where gluconeogenesis (GNG) comes in. It’s the process that makes glucose. And protein can be used in this process.

Protein as an Energy Source

Perhaps the easiest way to understand protein’s role as an energy source is to look at a flow diagram.

If we trace the path of protein we can see that it first gets broken down into its constituent amino acids. The carbon skeleton of amino acids can then be used to make energy. It can go to replenish glycogen stores in the liver and the muscles, and used in the production of ketones.

Beyond these storage mechanisms, there is also a small amino acid reservoir in the blood.

If all the functions of amino acids are taken care of, and muscle and liver are filled with glycogen, amino acids can be deaminated, turned into urea, and excreted in the urine.

And finally, the great fear, they can be stored as fat via ketogenesis / lipid synthesis.

There is not one set path that protein takes. The numerous “protein paths” depend on a multitude of factors including energy balance, hormonal influence, and need.

But let’s address the primary concern—protein and elevating blood sugar.

High Protein Diets and Blood Sugar

If you eat a high carb / sugar meal and can watch what your blood sugar does, you’ll often find a rapid rise in blood glucose. However, with protein you don’t tend to see this.

High protein meals tend to result in better blood sugar control with steady postprandial blood glucose and the absence of large blood sugar swings.

Because some observational studies suggest that higher red meat consumption increases type 2 diabetes risk, researchers decided to do a systematic review of randomized clinical trials, to test these observational studies. They hypothesized that higher red meat consumption would negatively influence markers of glycemic control and inflammation. To their dismay they found that consuming red meat above the (measly) recommended intake had zero negative influence on glycemic control or inflammation. (r)

I find it helpful to think of protein as a “slow release” energy source that requires approximately 1/2 the insulin as carbohydrate.

This is especially important for people with pre/diabetes/hyperinsulinemia. And yet this group of people tend to worry the most about eating too much protein out of the fear that it will be converted to blood sugar.

But blood sugar issues are a carbohydrate problem, not a protein problem.

Macronutrients and GNG

To address this fear, I think it’s 1st necessary to consider the alternatives of trying to avoid GNG.

Fat can also turn into glucose via its glycerol backbone. Most people don’t consider fats as a substrate for GNG, but they are.

Further, lactate can be turned into glucose. Lactate is a byproduct of working your muscles, and it’s used for GNG via the Cori Cycle. (r)

So, we have this situation where carbs turn to sugar, and protein and fats can both be turned into sugar via GNG. Not to mention, working your muscles produces byproducts used in GNG and glucose production.

So, what is the solution — don’t eat anything and don’t workout?

What to do about GNG?

I would propose that worrying about GNG is not the answer.

It’s a normal, natural, and necessary process.

Further I would submit that maintenance / building lean body mass (LBM) is more important than deep ketosis for most health objectives (including type 2 diabetes) and that the steady postprandial rises in blood sugar from protein aren’t what diabetics should be most concerned about.

A foundational principle of increasing insulin sensitivity (and thus reversing diabetes) is building muscle. This often requires at least a moderate protein intake combined with working out. Two things that we just learned can be used in GNG.

And while protein and lactate can be used in GNG, a low protein diet and not working out is not the solution to better metabolic function.

High Protein Diets and Gluconeogenesis: “Demand Driven”

So, we know protein CAN be turned into glucose, but when does this happen?

Turning protein into glucose via GNG is energetically expensive. It’s not something the body just defaults to. Rather, it is largely “Demand Driven.”

“…under almost any physiological situation, an increase in gluconeogenic precursor supply alone will not drive glucose production to a higher level, suggesting that factors directly regulating the activity of the rate-limiting enzyme(s) of glucose production normally are the sole determinants of the rate of production; hence, there will be no increase in glucose production if the increase in gluconeogenic precursor supply occurred in the absence of stimulation of the gluconeogenic system.”

Fromentin et al. “Dietary proteins contribute little to glucose production, even under optimal gluconeogenic conditions in healthy humans” Diabetes. 2013 May; 62(5):1435-42

Let’s unpack this research a bit.

Rate of Gluconeogenesis

Gluconeogenesis is an ongoing process. It happens in the fully fed state and it happens in the starvation state. And at a fairly consistent rate.

“The rate of GNG does not materially change based upon the infusion of lactate, glycerol, or alanine, even when infused at a rate which caused 5X uptake of the substrate into the liver.”

Jahoor et al. 1990, “The Relationship Between Gluconeogenic Substrate Supply and Glucose Production in Humans.” (r)

Ninety percent (90%) of all GNG results from just 4 molecules: lactate + glycerol + alanine + glutamine. But just because you mix these ingredients together you don’t necessarily get GNG. Because it is largely a demand driven process, not supply.

For example, let’s use an analogy. Say there is a company that sells widgets, and they have 2 options of how they can manufacture them:

1. They can manufacture 1,000 widgets up front, store them in inventory, and then ship them out as orders come in.
2. They can just make the widgets as orders come in without any upfront manufacturing.

Gluconeogenesis is like the second option. It’s driven by demand, by the “orders” coming in. It doesn’t just make a bunch of excess widgets even if it has all the materials to make them.

But if you are on a low carb diet and the body needs glucose, how does the rate of GNG not increase?

It makes sense that if you aren’t eating glucose (carbs) and the body needs a constant supply of blood glucose, then the rate of GNG would need to increase to keep this steady supply. But this doesn’t happen.

It turns out the body doesn’t use as much glucose when glucose isn’t consumed in significant quantities. It uses more fat for energy. And thus, GNG remains stable.

“The hormonal changes associated with a low carbohydrate diet…indeed favor gluconeogenesis. However, the body limits glucose utilization to reduce the need for gluconeogenesis.”

Manninen. “Metabolic Effects of the Very-Low-Carb Diet: Misunderstood “Villains” of Human Metabolism. J Int Soc Sports Nutr. 2004; 1(2):7-11

High Protein Diets and Ketogenesis

So to recap: if you eat a low carbohydrate diet and GNG doesn’t increase, the body needs to get energy from fat.

But let’s first address the issue going through your mind (if you are keto):

When I eat a lot of protein my ketones go down.

Protein can inhibit ketogenesis to varying degrees.

If the liver is getting plenty of amino acids there is a decreased need to oxidize fatty acids due to an increase in glucose oxidation, and thus there is less ketone production.

But this is largely a non-issue unless certain depths of nutritional ketosis are required for specific medical conditions (i.e. epilepsy, certain cancers, etc.).

It is very important to note, however, that your blood / urine ketone numbers aren’t telling you the full story.

For example, if you are burning your own body fat, using fatty acids as a primary fuel source, your ketones likely won’t be high whatsoever. Because you will be using these ketones for energy, not wasting excess ketones in your urine.

This brings us to the concept of endogenous vs exogenous ketosis.

Endogenous vs Exogenous Ketosis

You can enter nutritional ketosis by eating a lot of fat and very little carbohydrate. It usually doesn’t take too long before you start using fat as your primary fuel source. As you do, you make ketones as a byproduct of fatty acid oxidation.

However, the fat used for energy can be either dietary fat or liberated fat from stored adipose tissue. So, when you measure ketones you don’t know if they are being produced from fat stores (endogenous ketosis) or your last meal (exogenous ketosis). In fact, it’s more than likely from the meal you just ate if you measure any significant amount of ketones.

If you worry about your ketone numbers, it’s important to ask yourself what your real goal is. Is it really some number on a stick?

If so, just eat more butter and less protein and carbs.

Or is your real goal perhaps fat loss, or mental clarity, or enhanced energy, or general health and wellbeing?

If this is the case, that ketone number may not be telling you all that much.

Hormones: Insulin vs Glucagon

The two main drivers of gluconeogenesis (as well as ketogenesis) are insulin and glucagon. It’s the ratio and interplay of these two hormones that determines energy utilization and storage.

For example:

Low Insulin + High Glucagon = Nutritional Ketosis

Each macronutrient has specific effects on these hormones.

• Carbohydrates: ⬆ insulin and ⬇ glucagon
• Protein: ⬆ both insulin and glucagon
• Fat: ⬆ glucagon and doesn’t impact insulin too much

Insulin:Glucagon (I:G) Ratio

High I:G Ratio

When the I:G ratio is high, it means insulin is predominant, and thus the body is in an anabolic state (a state of building and storing-—more on anabolic vs catabolic states soon).

The Standard American Diet (SAD) has an I:G ratio around 4.0. This means glycogenesis and lipogenesis (storing glycogen and fat) are predominant. We are constantly in the state of storing energy.

This ratio also leads to the inhibition of autophagy and ketogenesis.

Interestingly, in this high ratio (high carb) state, more protein tends to further increase the ratio in the anabolic direction.

Low I:G Ratio

The I:G ratio declines when you need GNG.

When the I:G ratio is low, it means glucagon is predominant, and thus the body is in a catabolic state (energy mobilization).

This state mimics the fasted state where we see increases in insulin sensitivity, autophagy / mitophagy, lipolysis, and BAT activation.

In a low ratio state (low carb, ratio less than 1.5), more protein does not increase the ratio, but rather the ratio stays about the same.

The reason is that insulin rises to move amino acids into cells. But insulin is non-selective, which means it will also escort glucose from the blood into cells too.

The body must replace this blood glucose, and with little to no carbohydrate in the meal, the body does this by secreting glucagon which signals the liver to release glucose (which was stored there as glycogen). This glucagon further stimulates lipolysis (liberation of fat stores) and ketogenesis (creation of ketones).

Red Meat and Ketones

It’s worth noting here that carnitine is needed to escort fat into the mitochondria for oxidation.

Low I:G Ratio (Fat and Protein – i.e. Red Meat) + Carnitine (i.e Red Meat) = Ketones

Gluconeogenesis and Cortisol

A final point to discuss is cortisol’s role in GNG.

There is a common fear around eating a high protein diet in that it’ll stimulate GNG which requires cortisol. And chronically elevated cortisol is a stressor and damaging.

ERGO: A high protein / low carb diet ➡ GNG ➡ Cortisol ➡ Stress and Damage

Beside the fact that we just learned that a high protein diet doesn’t increase the rate of GNG…

GNG does not require elevated cortisol.

When blood sugar drops (below 65 mg/dL), glucagon is released which causes the liver to release stored glycogen as glucose into the blood. This happens BEFORE blood sugar gets low enough to trigger elevations of cortisol.

The blood glucose threshold for glucagon production is around 65 mg/dL.

The blood glucose threshold for cortisol elevations is around 55 mg/dL.

The body does not want to allow hypoglycemia (low blood sugar). It’s a dangerous state. One safety measure to prevent this is cortisol. If the blood sugar gets too low (55 mg/dL), the body releases cortisol which has a function of liberating glucose into the blood. It’s part of the sympathetic response, the “fight or flight,” that arms the body with necessary energy in emergencies.

The blood glucose threshold for cortisol production is around 55 mg/dL, a level below which glucagon would have already been released to increase blood glucose levels.

High Protein Diets and Gluconeogenesis: Conclusions

In short:

Steak doesn’t equal Cake.

There is substantial evidence that protein does not increase the rate of GNG, and the I:G ratio controls glucose production and ketogenesis, and this ratio doesn’t change much in low / no carb dieters with variable protein consumption.

There is no evidence that consuming excess protein will increase glucose production from GNG. Yet much evidence that suggest it does not.

Lin et. Al “Hormonal Regulation of Hepatic Glucose Production in Health and Disease” Cell Metabolism. 2011; 14(1):9-19

There are compelling arguments that protein does increase glucose oxidation in no / low carb dieters which can decrease ketone production, which is often a non-issue with respect to most people’s health objectives.

At the end of the day, the fear around eating too much protein because of GNG is unfounded in most cases. Besides specific medical conditions that call for certain depths of nutritional ketosis or people who just feel or do better at certain levels, restricting protein often isn’t the solution. In fact, as we’ll unpack, the opposite is often the strategy to achieving desired health outcomes.

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#2: High Protein Diets (Meat) and Gout

Too much meat will cause gout!

A common fear around eating a lot of meat is gout. And anyone that has suffered from gout will tell you this fear is justified. I’ve heard gout described as “stepping on broken glass and trying to ease the pain with a blow torch.”

Gout results from an abnormal accumulation of uric acid in the blood which crystallizes in joints, classically the big toe.

A major source of uric acid comes from the metabolism of purines. And since meat is high in purines, the oft heard recommendation for gout: avoid meat.

Meat ➡ Purines ➡ Uric Acid ➡ Gout

But there is a problem with this logical train of thought.

Over 90% of elevated uric acid is from impaired clearance, not the overproduction of uric acid. (r)

It’s the kidney’s job to filter uric acid out of the blood. But elevated insulin impairs the kidney’s ability to do its job.

The evidence suggest that most cases of gout are a result of metabolic dysregulation (hyperinsulinemia) as 3 out of 4 people with gout have metabolic syndrome. (r, r, r)

Low Purine Diet

When we look at the standard dietary recommendations for gout – A Low Purine Diet – it might be wise to question this approach. Low purine foods are mostly carbohydrate-based: cereals, bread, pasta, flour, sugar, and fruit.

These stimulate insulin far greater than purine-rich foods like meat.

And just as low cholesterol diets have a trivial effect on serum cholesterol, and low-salt diets have an insignificant effect on blood pressure, low purine diets have a negligible impact on uric acid levels. (r)

Gout: Blaming a New Problem on an Old Food

Gout is a relatively new disease that has increased 5X since modern dietary recommendations.

“Gout is unknown in Eskimos and Northern Indians despite their purine-rich diet.” (r)

Research done on the well-known Atkins Diet showed dramatic decreases in serum uric acid despite its substantial purine content. (r)

Perhaps we’ve pointed our finger at the wrong food groups.

The Gout—Fructose Connection

If we examine fructose we can get a better picture of gout. Fructose accelerates the breakdown of ATP, which produces adenosine, a form of adenine which is a purine. This stimulates the synthesis of purines directly.

Further exacerbating the situation, the metabolism of fructose creates lactic acid which reduces uric acid excretion. Combine this with elevated insulin and you get high levels of uric acid in the blood and impaired clearance. A recipe for gout.

Alcohol, like fructose, burns through ATP.

ATP ➡ Purines ➡ Uric Acid

Drinking until intoxication can double uric acid levels even though alcohol contains no purines. Rather purines are produced via metabolism of ATP and clearance is impaired because alcohol interferes with the kidney’s ability to excrete them. (r, r)

High Protein Diet (Carnivore Diet) and Gout

“Hi Doc, just a note to tell you I suffered from chronic gout for 5 years. It got to the stage that I started doubting if life was worth it. My daily pill intake was about 4 to 5 myprodol and about the same number of Voltaren or Ibuprofen, plus a gout pill pack of a mixture of 9 different pills.

 This was the norm for as long as I could remember…My brother-in-law told me about the Meat Health website. The next day I started with the 30 day guide….so far I’ve lost about 12 kg. I feel a lot better and most importantly I’ve had No Gout.

This is a life changer for me.

—Email from a Saturday 7 reader

I’ve received numerous messages like this one. It seems to be the “rule” not the “exception.”

However, in the early stages of transitioning to a meat-based / purine-rich diet gout can flare up.

Ketones can compete with uric acid for excretion, and for some people this can cause a temporary accumulation of uric acid until the body becomes more efficient at using ketones.

Adapting to ketone utilization and accompanying drops in insulin, uric acid excretion often returns to normal, and gout tends to resolve.

Gout Conclusion

It’s not the consumption of dietary purines (i.e. meat) that results in gout, rather the buildup of uric acid as a result of elevated insulin that impairs the kidney’s ability to excrete it. This is exacerbated by excessive fructose and alcohol consumption.

I think the current dietary recommendations for gout need serious reconsideration. (r)

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#3: High Protein Diets and Kidney Disease

While we are talking about the kidneys, the next major concern about high protein diets is:

Won’t all that protein ruin your kidneys?

The argument that protein “strains” the kidneys comes from this train of thought – protein contains nitrogen and the kidneys filter out nitrogenous wastes (creatinine and urea) and thus more protein = more strain on kidneys.

While perhaps a logical train of thought, we need to evaluate the data.

Kidney failure has doubled since the 1970s. Yet protein consumption has been fairly consistent.

The #1 cause of kidney failure is diabetes. Responsible for about 44% of cases. The #2 cause of kidney failure is hypertension (28%).

This means that 72% of chronic kidney disease could be controlled via blood sugar and blood pressure control.

This is a metabolic issue. Not a protein problem. (r, r, r, r)

The reason this happens is because chronic high blood sugar, insulin, and blood pressure damage the small blood vessels (the glomerulus) that feed the kidneys. This microvascular disease causes kidney failure. (r, r, r)

High Protein Diets and Kidney Function

Blood Urea Nitrogen (BUN) and Creatinine

If you go on a high protein diet you may see changes in renal function. However, elevations in BUN (blood urea nitrogen) or creatinine doesn’t necessarily indicate a problem. It often just reflects you are eating more protein than the Standard American Diet (SAD).

The changes in kidney function as a result of a high protein diet are expected and normal. These adaptive mechanisms are well within the functional duties of the kidneys.

Simply put, high protein diets don’t cause kidney damage. (r, r, r, r, r, r)

“…daily protein ingestion above dietary recommendations, no convincing evidence could be ascertained for kidney function decline relevant relationships with urinary albumin excretion, renal GFR, and kidney stone risk” (r)

Creatine Myth

For a long time there was concern that creatine supplementation would damage the kidneys. Creatine, high in red meat, is mostly (>90%) stored in muscles. So, the more muscle you have, the more creatinine you produce. Thus a high animal protein diet (or creatine supplementation) combined with a good amount of muscle mass can elevate creatinine (compared to SAD), which can falsely be interpreted as kidney damage. (r)

If you are concerned about a high protein diet and kidney health, instead of just looking at creatinine alone which can be “falsely elevated” due to muscle mass and protein consumption, get a Cystatin-C GFR test which removes protein as a confounding variable. (r)

Further, not only does the evidence not support high protein diets causing kidney disease, but much research has shown that protein restriction has been largely unsuccessful in slowing the progression of pre-existing chronic kidney disease. (r, r, r)

“It’s a concept that’s been around for at least 50 years and you hear it all the time: higher protein diets cause kidney disease. The fact is, however, that there’s no evidence to support this hypothesis, in fact, the evidence shows the contrary is true: higher protein increases, not decreases, kidney function.”

Stuart Phillips, professor and prominent protein researcher

High Protein Diets and Kidney Disease Conclusions

The surest path to kidney disease is a high sugar/carb diet inducing chronic elevations in blood sugar, insulin, and blood pressure.

Another route is inducing oxalate-based nephritis via a heavy oxalate / plant-based diet.

While protein has been a good scapegoat for kidney disease, it’s simply not a dependable way to induce kidney damage.

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#4: High Protein Diets and Bone Health / Acid

“Meat is acidic.
It will leach calcium from your bones.”

People worry that a high protein, meat-based diet is acidic.

The hypothesis goes like this: Amino “acids” from protein increase acidity in the blood. Therefore, to balance the pH the body leaches calcium and other alkaline compounds from the bones.

Worse, an all meat diet without dairy seems to be quite low in calcium. And with high protein diets it’s common to see an increase in the amount of calcium excreted in the urine. So, the fear is that the acid which is derived from the protein in meat, causes calcium to be leached from the bones to balance the pH, and then this calcium is urinated out.

Low calcium + High acid meat = Osteoporosis…Right?

High Protein Diets and Calcium Absorption

There are a few problems with this train of thought.

The first problem is that dietary protein improves gut absorption of calcium, some research showing between 300 – 400%. (r)

Further, “dietary protein works synergistically with calcium to improve calcium retention and bone metabolism.” (r).

High Protein Diets and Osteoporosis

Much research shows the positive effect of dietary protein on bone mineral density and further suggests that low, not high protein, is detrimental for bone health. (r, r, r)

One (of many reasons) I’d caution against a low protein diet is the reduction in intestinal calcium absorption, which can lead to hyperparathyroidism.

In this situation the parathyroid secretes hormone that increases osteoclast activity, which breaks down bone tissue to release calcium. (r)

And simply eating lots of calcium and dairy doesn’t solve the problem.

There is a lack of evidence that dairy or calcium supplements strengthen bones or protect from osteoporosis.

Americans eat more dairy than almost any other country and have some of the highest rates of osteoporosis.

Anthropology and Bone Health

The connection between high protein intake and bone health is common knowledge in anthropology.

Anthropologists distinguish the remains of hunter-gatherers from agriculturalists by examining the bones: high protein eating hunter-gatherers have larger, stronger, denser bones.

High Protein Diets: Muscle Mass and Bone Health

Perhaps one of the most important considerations in bone health is muscle mass. Protein is critically important to maintaining muscle especially as we age.

More muscle is associated with stronger bones and a decreased risk of osteoporosis. (r)

It’s Not Just Meat

The last important thing to mention in the “meat is acidic” argument is that grains have an acid residue too.

Oats and brown rice have a higher acid potential than most meats. Further, they don’t aid with calcium absorption, rather contain antinutrients like phytic acid and oxalates that can interfere with calcium absorption.

Conclusions: Meat, Acid, Calcium, and Bone Health

When researchers look to see if high protein diets increase the risk of bone fractures, not only do they not find a correlation, rather they find protein intake is positively associated with bone mineral density. (r, r, r, r, r)

And, worth mentioning here, I don’t think supplemental calcium is necessary on a meat-based diet. In fact, I would worry if someone were supplementing calcium on a meat-based diet as it could lead to hypercalciuria and renal stones.

So, if you want strong bones, don’t skimp on the meat / protein.

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#5: High Protein Diets and Longevity

The Longevity Arguments Against High Protein Diets

There is a theory that protein restriction can increase longevity. It’s based on the idea that less protein will improve the stability of metabolic networks.

Basically, the idea is: Too much protein will lead to an accumulation of damage over time (oxidative stress) which leads to aging. And since some research shows that protein restriction can reduce levels of oxidative damage, we have this “protein restriction – longevity” hypothesis. (r)

Of Mice and Men — Metabolism

Most of the research in this field has been done on mice. One trait (of quite a few) that distinguish mice from men is that mice have 7X the metabolic rate of humans. Thus, they have far greater levels of oxidative stress.

With this in mind, it makes sense that mice respond favorably to interventions that reduce oxidative stress.

Extrapolating longevity research that has been done on mice to predict human outcomes is inherently flawed.

Mice live for about 2 years. Humans about 80.

If you combine this fact with the difference in metabolism, drawing any meaningful results is difficult if not impossible.

Moreover, proponents of protein restriction based on this limited research are the same people that tend to also be proponents of fasting. Which is hypocritical if you consider the fact that if a mouse fasts for 24 hours it loses over 20% of its body weight. Fast a mouse for 5 days and it dies. (r, r, r, r)

High Protein Diets: IGF-1 and mTOR

What about the research on growth factors like IGF-1 and mTOR?
Both are associated with cancer and age-related diseases.

There are two opposing “forces” or states that I think are greatly misunderstood — the anabolic state and the catabolic state.

Anabolism is the state of growth, building, and storing. It’s a state of energy abundance. It’s associated with muscle growth and fat storage. It’s also associated with mTOR, insulin, and IGF-1.

Catabolism is the state liberating stored energy, breaking down, and clearing out. It’s a state of energy deficit. It’s associated with starvation, or more commonly “fasting,” and initiating processes like ketogenesis and autophagy.

For much of my early adult life, I focused on anabolic factors like stimulating mTOR and IGF-1 and the strategic “spiking” of insulin post workout. These were processes that enabled me to build muscle and the body I wanted.

Later I drank the “catabolism Kool-Aid.” I did regular fasting and measured ketones in the hopes of finding the holy grail of health.

But what I’ve come to believe is that balancing these states is the key. Let’s look at this balancing act in the context of longevity.

High Protein Diets: Anabolism vs Catabolism

Protein: Anabolic State and Muscle Mass

In any discussion on longevity it is imperative to discuss muscle.

Muscle mass, independent of fat mass and cardiovascular and metabolic risk factors, is inversely associated with mortality risk.

In research by Srikanthan, he suggests that anabolic processes that promote muscle building (i.e. IGF-1 and mTOR) are associated with longer survival.

Simply put: muscle mass is one of the biggest predictors of longevity. (r, r, r, r)

But we can also look at this from the other vantage point.

Protein: Catabolic State and Muscle Wasting

Decreases in muscle mass as we age is one of the highest predictors of all-cause mortality.

The reason why is that it leads to sarcopenia — the impairment of physical function from loss of muscle mass.

Sarcopenia increases the risk for:

• Disability (r)
• Nursing Home Placement (r)
• Fractures (r)
• Falls (r)
• Hospitalizations (r)
• Reduced Quality of Life (r)
• Premature Death (r)

Older adults require more protein to offset sarcopenia, frailty, and associated morbidities. (r)

“I think the most important thing to consider as a macro-principle of longevity is that the longer you can preserve muscle mass, the better.”

Dr. Peter Attia, MD

But like I mentioned, I think the key is a balance between these forces. (r)

The modern diet is heavily skewed towards the anabolic state. We eat continuously. Three meals, snacks in between, dessert after. And most of this food is not protein. It’s plant-based carbohydrate and fats. Foods that highly stimulate the anabolic pathway (i.e. insulin, mTOR, etc.).

But not only are we continuously stimulating anabolism, these foods combined with a lack of exercise / muscle stimulation equal fat storage, not muscle building. So we aren’t even getting the benefits of anabolism, only the detriments (continual fat storage and accumulation and subsequent metabolic dysregulation).

It’s why we see such “positive” results from studying catabolic processes (like fat loss, fasting, and autophagy). It swings this balance back in the other direction.

With a Standard American Diet that has us always in the anabolic state it makes sense that we see such high rates of obesity and diabetes. And I can’t help but think many cancers, typified by uncontrolled cellular growth, are related to this continuous anabolic stimulation.

But thinking that fasting is the answer to the fountain of youth is misguided. While the benefits of autophagy and clearing out waste seems obvious, so should the idea that this catabolic process is “breaking down” tissues, cells, and molecules.

Skew too far in the “break down” direction and I don’t think you’ll find a robust healthy old body at the end of that road. Instead, you’ll likely find frailty, aging, and graying. It’s a picture that I see with many people who have practiced strict veganism and prolonged fasting.

Both anabolic and catabolic states have beneficial and detrimental effects.

Anabolism builds muscle but will also store nearly unlimited amounts of fat. Catabolism clears out waste via autophagy, but can also waste away muscle.

Over-tipping the scale in either direction can have adverse effects. Too much anabolism and you end up obese with metabolic syndrome. Too much catabolism you end up wasting away with sarcopenia.

The key is balancing the beneficial aspects of anabolism and catabolism.

But modern society tips the scales in the worst directions of each of these two processes. In the anabolic state we layer on excess fat, not muscle. And in the catabolic state, we waste away muscle, instead of clearing out waste. We are fat and weak.

I think most peoples' goals should be to optimize the anabolic pathway for lifelong muscle building and maintenance, and balance this with catabolic processes like some fasting, or fasting mimicking via ketosis / low carbohydrate intake.

Meat-Eating and Longevity

As I mentioned in “Evidence for a Meat-based Diet” there are numerous factors that go into living a long life. One of those factors is undoubtedly diet. And the evidence suggests, the more meat you eat (and thus protein) the longer you live.

Telomeres

When studying longevity an interesting place to start is looking at telomere length. Telomeres affect cell lifespan. The longer the telomere the longer they live.

There was a study on red meat that found an “unexpected relationship” between the frequency of red meat consumption and telomere length. More so than exercise or any other factor, red meat consumption correlated with longer telomeres. (r)

But do longer telomeres result in longer life?

Meat-Eaters

Trying to isolate for “pure meat-eaters” today is nearly impossible but Hong Kong is about as close as we can come. They eat about 1.5lb of meat per person/day. The most in the world. Turns out they have the longest life expectancy in the world. (r, r)

Japan also recently hit an all-time high in life expectancy in tandem with their meat-eating. Australian men eat more meat than almost anyone and they top the world’s men in longevity. On the small island of Iceland, they have more centenarians per capita than almost anywhere in the world. Living in the tundra is not conducive to plant-based food products, so their traditional diet has always been predominantly meat-based. (r, r)

Though the Icelandic diet has changed a lot in the past half century, some of the healthiest traditional fare remains.

Freshly caught coldwater fish is both wildly popular and widely recognized as a dietary superstar…Additional protein staples in Iceland are lamb and beef…Iceland’s semi-wild, free-ranging beasts meander at will into the mountains each summer, grazing on natural grasses, sedges, and whatever other odd victuals they’re meant to consume.

The Land that Forgot Death (r)

On the flip side, people in India eat about the least amount of meat in the world. They also have one of the shortest life expectancies (as well as the highest rates of diabetes and depression in the world). Yet, the women in India who eat meat 5 times per week are less likely to suffer from obesity, heart disease, and cancer, while having lower rates of insulin resistance and inflammation than the non-meat eaters. (r)

A recent 175 country, cross-sectional independent review found that “meat intake, not carbohydrate crops, as one of the significant predictors of life expectancy.” (r)

This is consistent with the data from FAO that shows as meat-eating increases so does life expectancy.

Yes, this is epidemiology which comes laced with flaws and limitations, but these findings can’t be ignored. Especially because they are in stark contrast to popular claims of plant-based diets offering longevity benefits – which they don’t. (r, r)

A recent study looked at 400,000 people to critically review the role of vegetable consumption and (the supposed) decreased risk of cardiovascular disease (the #1 killer worldwide).  Their conclusions: “after adjustment for socioeconomic and lifestyle factors, residual confounding is likely to account for much, if not all, of the remaining associations.” (r) 

Basically, the benefits of eating vegetables, as seen in previous epidemiological studies, are mostly if not totally, due to confounding. 

And in fact, research is showing red meat intake to be inversely associated with cardiovascular disease and with cancer – two of the leading causes of death. (r, r)

Plant-Based Eaters

The short life spans found in India are consistent with the findings in vegans who typically eat a low protein diet.

There was a massive study conducted at Oxford that compared all-cause mortality among regular meat-eaters and vegans.

Although these were not pure meat-eaters or even “meat-based” eaters (they ate other junk too) they still had a 14% decrease in relative risk of death compared to vegans. (r)

Meat won’t give you a heart attack and vegetables won’t save you from one (unless your broccoli prevents you from eating donuts). Eat meat. Live Long.

High Protein Diets and Longevity: Conclusions

The research in support of protein restriction for longevity is weak. And it must be contrasted with the known detriments of a low protein diet like sarcopenia and resulting frailty, reduced quality of life, and premature death.

Beyond just protein, meat seems especially important in promoting longevity.

And while many factors go into longevity, some of which are out of our control, I can’t end this section without some tips that I think do move the needle in the direction of living a long life:

• Don’t eat foods that didn’t exist 100 years ago (perhaps even 10k)
  • Eat a lot of meat and throw in some occasional fasting
• Workout
  • Build and maintain muscle as you age
• Sleep
  • Prioritize 7-8 hours of sleep/night
• Sun
  • Get some
• Emotional Health
  • Reduce Stress
  • Cultivate Social Connections
  • Find a sense of purpose and meaning to life

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#6: Meat-based High Protein Diets (Carnivore Diet) and Amino Acid Balance

What about the Carnivore Diet and out-of-balance amino acids — should I supplement?

As we’ll get to in Part 2 shortly, you don’t need the same amounts of each amino acid.

Branched chain amino acids (BCAAs) account for about 1/2 of your essential amino acid (EAA) requirements. You need nearly 10X more leucine than tryptophan, for example.

But a common concern among those on high protein diets (carnivore / meat-based eaters) is not if they are getting enough of all the amino acids, but rather if they are getting too much of certain ones.

If you eat a lot of muscle meat, you consume a good amount of methionine, which as the name suggests, is responsible for methylation. Glycine provides a buffer to this methylation.

If unbuffered, hypothetically it could cause issues with collagen synthesis. Also, hypothetically, methionine restriction could increase lifespan.

But the 1st point to make here, is one we’ve already made. Like the longevity research we just talked about, the studies on methionine have been done on mice, and as the researchers say themselves, this can’t be extrapolated to humans:

"The duration and severity of the DR [dietary restriction] regimen that achieves maximal longevity may not be feasible outside of lab settings. In humans, DR may be associated with severe side effects and elevated risk of malnutrition, especially with regard to protein and micronutrient requirements. Although analyses of those practicing CR [calorie restriction] showed that humans exhibit some of the same molecular and metabolic signatures observed in long-lived CR rodents, currently it is impractical to directly apply CR to increase longevity and reduce the risk of age-associated diseases in humans." (r)

The 2nd point is that when you stop eating so many carbs / sugar a lot of things change.

For example, glucose can compete with vitamin C for absorption, thus with less sugar in the diet, less vitamin C may be necessary. Similarly, research has shown that glucose and galactose (sugars) impair the absorption of glycine. And thus, with a low / no carb diet you can see increases in the absorption of glycine. (r)

This is perhaps why we see beneficial outcomes when people with metabolic disorders such as cardiovascular diseases, inflammatory diseases, obesity, cancers, and diabetes are given supplementation with glycine. They can be deficient because of impaired absorption due to chronically elevated blood sugar. (r)

The 3rd point is evidenced by simply looking at the numbers.

Evaluating these concerns in detail, we can see that in the amino acid composition of various cuts of meat, muscle meat has more glycine than methionine. (r)

The final, 4th point, is glycine is not an essential amino acid. It is synthesized from choline, serine, hydroxyproline, and threonine. But in certain circumstances (i.e. metabolic dysfunction) the body can’t make as much as it needs, and is therefore considered “conditionally essential” (more on this in Part 2).

But not only does a meat-based diet provide plenty of glycine, it also gives the body ample building blocks to synthesize glycine all on its own.

This diagram paints a useful picture of protein / amino acid balancing via dietary intake, loss, and recycling.

Coming In: With a meat-based diet you consume all the amino acids in plentiful quantity to perform all its essential roles.

Going Out: We lose amino acids through:

• Oxidation
• Intestinal Losses
• Skin (sweat and skin cells)
• Urinary Excretion
• Synthesis of other amino acids
• Irreversible modification
• Synthesis of non-protein substances

Recycling: And finally, the body has a remarkable ability to recycle proteins and their amino acids.

It’s a fine-tuned “checks and balances” machine. And I’m not saying these balances can’t be thrown off, they surely can, as we see in metabolic disorders, but it’s unlikely that you are going to “overeat” a single amino acid if eating whole food / meat.

Perhaps supplementation of megadoses of individual amino acids could cause problems, but worrying about a methionine:glycine ratio probably isn’t worth the stress.

And if you are stressed about it, it’s not too difficult to increase your glycine intake via eating connective tissue like tendons, collagen, or bone broth; or you can simply supplement with some hydrolyzed collagen or pure glycine. The potential risks associated with glycine supplementation are small, and the upside of ease-of-mind could easily be worth it.

And if you are really stressed about it (probably causing more damage than anything) you can test for adequacy of glycine via pyroglutamate, glutathione, and serum glycine levels.

In Part 2 we will talk much more about amino acids, quantities, essential vs conditionally essential, and more.

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Part 2: Protein — The Most Essential Macronutrient

Hopefully, we can now put the fears of protein behind us. But we need to look at the other side of the coin. Fears of inadequate protein, which I think are more justified.

Pragmatically, protein can be considered the only macronutrient you have to worry about getting enough.

The human carbohydrate requirement is 0 (so is fiber). The body can make all the glucose it needs. You can go the rest of your life without eating any.

And while there are essential fatty acids, the minimum needed for survival is very low (of course, this is not to say that low fat is optimal).

The 2 essential fatty acids (EFA), linoleic acid (an omega-6) and alpha-linolenic acid (an omega-3), which can’t be made by the body, are so abundant and easily obtained that it’s difficult to develop a deficiency.

To put this in perspective, to cause a fatty acid deficiency you’d have to eat a purified, zero-fat diet for weeks if not months before the first signs of a deficiency. (r, r)

However, the requirements for protein are substantially greater, and the consequences of protein malnutrition are severe.

Carbs and fats are made of carbon, hydrogen, and oxygen. But protein also requires nitrogen. So, the body can make carbs from protein and most fats from anything. But not so with protein.

Further, as we learned, “excess” protein isn’t stored in any appreciable way.

Combine these factors with our large essential amino acid (EAA) requirements, and you can see why protein is (pragmatically) the most essential macronutrient. You need to eat enough, and you need to eat it regularly. Otherwise, you start to eat into muscle and tissues and impair vital functions.

Protein Malnutrition

I think people should be concerned about inadequate protein intake.

Besides muscle loss and sarcopenia (which I’ve touched on and will touch on a bit more soon) inadequate protein can stunt growth, reduce immune function increasing susceptibility to infection, and cause serious psychological and behavioral changes.

• Irritability
• ADD
• Anxiety
• Apathy
• Depression

Inadequate essential amino acids (EAAs) put you at risk for lethargy, weakness, muscle wasting, impaired healing, accelerated aging, bone loss, hair loss, heart problems, hormone imbalances, mood disorders, weakened immune system, and ultimately it can be fatal. (r)

Extremely sad examples of this can be seen in less developed areas of the world where “Kwashiorkor,” aka “sugar babies,” suffer with distended bellies, stunted growth, apathy, listlessness, and high rates of infection. (r)

When we don’t meet the “floor” protein requirements, the body responds by doing whatever it can to force you to find this protein.

Protein Leverage Hypothesis

The “Protein Leverage Hypothesis” discusses this “protein floor” and what happens when it’s not met.

In 2005 David Raubenheimer and Stephen Simpson (who I’m going to refer to as “R&S”) proposed a novel solution to the obesity epidemic and related metabolic diseases (diabetes, cancers, heart disease, etc.). They said the key to the obesity and modern metabolic disease epidemics is “protein leverage,” a term they coined as the remedy for the diseases of modern civilization.

Simpson, SJ and Raubenheimer, D. 2005. Obesity: The protein leverage hypothesis. Obes. Rev. 6:133-144 (r)

In essence, they argue that protein is the underlying factor that determines how much we eat.

If you eat enough protein you won’t overeat. If you aren’t eating enough protein, instinctively you will overeat in an effort to compensate.

This hypothesis is based on the fact that many species regulate food intake by how much protein they need to maximize health and reproduction. “Leverage,” as used by R&S, is used to explain the fact that small changes in protein availability can trigger large changes in animal behavior.

Protein Leverage and Portion Control

This explains why portion control fails.

The argument is that the only reason you’d need portion control is if you overeat naturally. But R&S suggest this isn’t the case.

Rather, the reason you overeat is because you aren’t getting enough protein. Thus, shrinking your serving sizes via portion control only makes matters worse as your serving of protein shrinks even further.

R&S say you don’t need to shrink portion sizes, you need to increase your portion of protein.

Species Searching for Protein

In their research, R&S observed, again and again, that species in the wild can instinctually detect what they need for optimum health and fitness. But when their optimal nutrition isn’t available, a species will adapt.

They will hold off on mating, or shrink in size to save energy, or they may pick up and move all together as migratory animals do with the seasons.

Crickets will migrate to find protein. During the migration they will pass up on many possible sources of energy (i.e. like grasses) in search of protein. Many starve to death. And when they do, the other crickets will eat their traveling companions for the protein.

For example:

Crickets: Migrate and will become cannibals if deprived of protein.

Fruit Flies: Hold off on mating if they don’t get enough protein.

Birds: Self-select diets to reach optimal protein, increasing it during times of growth. Birds bred with more muscle also self-select higher protein diets.

Protein Leverage and Humans

From R&S’s research, they found that humans have a “protein floor” around 15% of their baseline homeostatic energy requirements.

According to USDA figures and the FAOSTAT database, the amount of protein available in the food supply has decreased to 12.5%. Making humans as a whole protein deficient.

Because the modern food supply is deficient in protein, people have to eat more calories to try and replace the lost protein. And to make up for this drop in protein, an average sized person needs to eat about 15% more calories.

Unconsciously and instinctively the body adapts and increases appetite. Protein deficiency leads to the consumption of a couple hundred extra calories/day, which correlates quite well with the calorie increase in the American diet since the 1970s according to NHANES data. (r)

In this regard, R&S argue that we act in a similar way to other species.

• Primates: Reliably overeat foods high in carbs and fat in order to get enough protein

• Rats: Overeat on low-protein foods until they get enough protein. After protein deprivation, they self-select higher protein food

R&S found that even mild deficiencies in protein result in overconsumption to compensate, which when compounded day after day can result in drastic outcomes in the forms of obesity and the sequelae of metabolic diseases that come from constant overfeeding.

Protein Leverage and Disease

The body seeks homeostasis. It balances everything. From temperature, to blood sugar, to energy usage and consumption.

But it will disrupt homeostasis when a threat poses a greater risk than the imbalance.

Such a situation arises with protein deficiency.

As far as the body is concerned, obesity, diabetes, and metabolic syndrome are preferable to protein starvation.

Protein is absolutely critical to nearly every process and structure in your body. Protein starvation scares the body like nothing else.

• Zero carbs – no big deal.
• Zero fat – no immediate big deal.
• Zero protein – imminent big deal.

Inadequate protein, a negative nitrogen balance, will waste away muscle, organs, and reproductive ability.

With inadequate protein, the body literally must “eat itself” to get the protein it needs.

To avoid this, the body responds by increasing appetite urging you, begging you, to eat. Unfortunately, this signal is a bit blunt. It doesn’t specify protein. In the wild, for most of human evolution, protein was basically a foregone conclusion when you hunted down an animal.

With today’s food choices, it’s the opposite. Instead of hunting down an animal, we’ll open the pantry or fridge and respond to this urge by eating carbs and fat. And we will eat over and beyond our homeostatic energy requirements in search of protein.

“Subtle changes in diet composition with respect to protein and carbohydrates seem to have major impact on spontaneous caloric intake.”

Astrup, A. et al. “The role of higher protein diets in weight control and obesity related comorbidities.” International Journal of Obesity, 2015.

To sum up R&S’s Protein Leverage Hypothesis:

With our current food supply, we must overeat. And to handle this excess of calories we store more and more as fat. Obesity and diabetes are the result of necessary over-consumption by the body seeking adequate nutrition from protein.

Carbohydrates and the Protein Leverage Hypothesis

While I’m a big fan of the work R&S did, I think the Protein Leverage Hypothesis tells part of the story, but not the whole thing.

I’m confident that if I ate adequate protein, over and beyond my “protein floor,” and then filled in the rest of my diet with donuts, I’d be in trouble.

I think protein is a huge part of this story. But I think carbs is another.

Because not only does inadequate protein cause an increase in caloric consumption, if those calories are replaced with carbs, the increase is even greater.

There have been a couple of studies done on obese kids and soda. When these kids stopped drinking soda their calorie intake dropped. And it dropped not just by the amount of calories from the soda, but even further. In essence, the soda (sugar/carbs) increased caloric intake beyond those attributable to the soda. (r, r)

So not only does the soda supply additional calories (versus water for example), but those calories make you need to eat even more calories. Double whammy.

Carbohydrates can promote hunger via several mechanisms, many through dysregulation of insulin.

• Insulin can interfere with leptin (which plays a key role in regulating energy intake and use) and lead to “leptin resistance.”

• Insulin resistance / hyperinsulinemia results in chronically high insulin, preventing you from tapping into your fat stores for energy which often results in a blood sugar roller coaster and hunger.

• Carbohydrates can cause alterations in hepatic metabolism and CNS energy signaling leading to chronic overconsumption.

• Carbohydrates stimulate the hedonic pathway (pleasure) creating habituation.

Combine inadequate protein and compensatory carbohydrate consumption and the obesity epidemic becomes less of a mystery.

Protein: The Most Satiating Macronutrient?

Much research since R&S’s original Protein Leverage Hypothesis has confirmed a “protein floor” around 15%. Research on satiety highlights this.

Until the 15% protein floor is met, protein is 100%, undeniably, the most satiating macronutrient.

Once this 15% threshold is met, protein’s superior appetite suppressing advantages do tend to gradually taper off.

But this 15% is just an approximation for a bare minimum. For example, the amino acid content of that 15% is very important. With plant-based proteins, the floor increases as these proteins tend to be incomplete thus upping the total requirement of protein.

And as we’ll get to, this 15% floor doesn’t mean you should stop there.

“One of the most striking findings of this study was the consistently strong and negative association with increasing percentage calories from protein and daily energy intake across all 3 BMI categories…if protein was increased from 15% to 25% of energy intake in an obese individual, this would be expected to be associated with a decrease in energy intake of 438 calories (if substituted for carbohydrates) or 620 calories (if substituted for fat).”

Austin, Ogden, Hill, “Trends in carbohydrate, fat and protein intakes and association with energy intake in normal-weight, overweight and obese individuals.” AJCN 2011

Hunger and satiety are complex.

Hormones are the most important factors that determine if you feel full or you go open the pantry again.

A general rule of thumb:

More Protein = More Appetite Suppressing Hormones

Amino acids stimulate the release of several hormones that activate satiety centers in the brain (GIP, GLP-1, PYY, CCK). They also suppress ghrelin, “the hunger hormone,” more so than either fat or carbohydrates.

Further, protein slows intestinal contractions to allow time to absorb all the amino acids, which increases satiety duration.

It’s telling to see how closely the body monitors protein to ensure we get enough.

The Brain: Protein and Appetite Regulation

Since we can’t store amino acids like carbohydrates or fat, the body needs mechanisms to ensure we consume enough protein on a regular basis.

Large neutral amino acids (LNAAs) can cross the blood-brain barrier and directly affect neurotransmitter levels with appetite suppressing effects. Or, in the absence of LNAAs, can leave hunger signals active.

In the brain we have a modulator called the “General Control Nonderepressible 2” (GCN2) which closely monitors amino acid balance.

Further, amino acids can affect the brain via stimulating mTOR (anabolic signaling), suppression of AMPK (catabolic signaling), and thus decreasing orexigenic neuropeptide Y, which increases anorexigenic peptide alpha-MSH. And so, again, we can see that if deficient in these amino acids, hunger signals get left on.

The brain also communicates with the tongue.

We have oral receptors in the mouth that can detect the presence or absence of amino acids in the diet. Which can signal to the brain “eat more” or “we’ve had enough protein.”

Basically, we have a communication highway between our mouth, our brain, and our appetite.

Hunger Beyond Protein and Carbohydrates

Appetite is impacted by more than just protein and carbohydrates. Certain fats can increase hunger too.

Vegetable oils, high in linoleic acid (especially soybean oil) can trigger overeating via endocannabinoids, resulting in the “munchies.” They, too, have a hedonic component that stimulates dopamine and habituation.

And while macronutrients and overall energy consumption play a significant role in appetite, they are not the only factors.

Other variables such as food volume, density, fiber, and even taste – not to mention psychological factors (i.e. stress eating) – all can play a role influencing hunger and appetite.

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High Protein Diets: An Evolutionary and Species Perspective

The “Protein Leverage Hypothesis” hints at an argument for high protein diets from a species-specific perspective.

I like to evaluate nutrition from various perspectives, one being a species / evolutionary / ancestral “zoomed out” perspective.

I like to step back and imagine rewinding the clock 100 years, 10,000 years, 200,000 years — what would humans have had access to eat? What does archeology and paleontology hint at what the human diet entailed throughout the ages? What did our ancestors’ anatomy and physiology suggest we ate?

I like to look at this “zoomed out” perspective because I think our ancestors left “bread crumbs” (terrible analogy) as to what we are designed to eat.

Before the Agricultural, Industrial, and Technological Revolutions that transformed the human diet, my guess is that humans had better instincts into our natural diet for optimal fitness.

Species in the wild don’t need a food pyramid to tell them what to eat. Because most species are designed to eat a certain diet.

A species natural diet is in accord with specific anatomical features; ones that enable cows to graze on grass and gorillas to digest leaves. Without special features it would be impossible to fuel their large bodies on seemingly nutrient poor grass and leaves. If a human eats just grass or leaves, we’d die. We are built differently than cows and gorillas.

I’ve talked about this anatomical and evolutionary perspective of nutrition in multiple articles (notably here, here, and here).

To summarize: Prior to the agricultural revolution, humans ate a whole lot of meat. Meat was the selective advantage that developed our absurdly large brains, transformed our gut anatomy, and underpinned our divergence from our primate ancestors.

If we look at isotope studies of fossils, we see that humans 50,000 years ago ate a diet nearly indistinguishable from carnivores. And prior to the Agricultural Revolution (~10,000 years ago) modern humans ate a diet where 30+% of calories from protein would have been the rule, not the exception. (r)

While I’ve discussed and argued for the obviousness of a meat-based diet from an ancestral perspective, the Protein Leverage Hypothesis is another piece of evidence in the case for humans eating a high protein, meat-based diet.

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High Protein Diets: Body Composition

The #1 reason people start a new way of eating is to lose fat. More specifically, to improve body composition. But this isn’t just a vanity goal. Improving body composition (fat loss / muscle building) is strongly correlated with improving most of the chronic diseases of modernization.

Before diving into how much protein to eat to improve body composition, it is important to understand the two sides of the body composition equation – fat loss and muscle building.

The Most Overlooked Aspect of Fat Loss

Fat loss is a primary health objective for most people. Over 70% of US adults are overweight or obese, which is evidence of a metabolic state that is complicit in most of the chronic diseases today. To combat this and achieve this primary health objective, it’s necessary to understand the importance of maintaining or even building muscle during fat loss. Muscles role in fat loss is easily the most overlooked aspect to fat loss success.

NOTE: The typical "caloric model" of fat loss is flawed  / misunderstood  in many ways (for example, we know different foods affect hormones in different ways which plays a significant role in determining fat loss) but I use basic terminology like "caloric deficit" and "caloric surplus"  to help clarify the overarching ideas in this section. (r)

While in an overall energy deficit required for fat storage mobilization, it’s paramount that most of this energy in reserve comes from fat and not lean body mass (LBM).

Otherwise, the loss of both LBM and fat, in tandem, can result in metabolic slowing, leading you in the direction of “skinny fat,” where body composition isn’t improved although the scale is dropping.

This is a recipe for rebound weight gain, and a significant reason why nearly all diets fail.

Caloric Deficit + Loss of LBM = Metabolic Slowing ➡ Fat Loss Plateaus, “Skinny Fat,” and subsequent Rebound Fat Gain

Not all weight loss is the same.

Many weight loss studies show that one-fourth of body weight lost is commonly LBM. Luckily, higher protein diets can help combat this. (r)

• High protein diets help preserve lean mass in dieters (especially lean dieters). To minimize lean-mass loss, dieting athletes should consume around 1.5g of protein / lb bodyweight. (r)
• When comparing higher protein diets with lower protein diets during an energetic deficit and exercise, higher protein diets promoted greater lean mass gain and fat mass loss (r)
• Eating more protein than dietary recommendations resulted in less hunger, increased energy expenditure, and preservation or increases in lean body mass (r)

Overall, the evidence suggests that 1g protein / lb of bodyweight is close to the minimum as far as maintaining lean body mass when in a prolonged caloric deficit.

Of course, many factors come into play besides total protein when it comes to preserving LBM in a caloric deficit. Other factors such as body composition, the severity of the deficit, and training schedule, all play an important role – but protein is a crucial factor in warding off the loss of LBM while in a caloric deficit. (r)

Study

Overweight young men were put in a steep (40%) caloric restriction diet combined with high intensity workouts for 1 month.

One group ate “high” protein = 1g/lb

One group ate “moderate” protein = 0.6g/lb (which I’d call LOW)

Both groups lost the same amount of WEIGHT.

But the high protein group (1g/lb) INCREASED LBM while losing fat. While the moderate protein group preserved lean mass, resulting in vastly different body composition changes.

The Protein Advantage

High protein diets have a metabolic advantage. Protein helps to maintain / improve LBM, induce greater thermogenesis, and is inefficient in energy production (GNG).

Energy is needed to process what we eat. This is called the thermic effect of food. And the energy requirements for each macronutrient is different:

• Fat = 0-3%
• Carbohydrate = 5-10%
• Protein = 20-30%

Varying macronutrient combinations can add up to several hundred calories per day. Compounded day after day, year after year, this can be the difference between obesity and diabetes versus a healthy body composition and properly functioning metabolism. (r, r)

Additionally, animal protein sources induce greater increases in thermogenesis than plant-based protein sources (i.e.“The Meat Sweats”).

Research has shown that people with chronically “elevated” levels of BCAAs (high in meat-based protein) are leaner, more insulin sensitive, and resistant to diet induced obesity. (r, r)

Many studies elucidate this protein advantage: high protein diets cause more fat loss compared to normal or low protein diets when calories are kept equal.

High protein diets help to make sustaining a caloric deficit easier by creating self-imposed deficits that aid in fat loss without standard calorie tracking. And they are often shown to be more satisfying and effective at reducing hunger during caloric restriction. (r)

Fasting and Body Composition

I think this is an important time to discuss fasting.

Many people use fasting as a tool to help control caloric intake.

It can be an effective way to create a caloric deficit. However, it’s important to mention the potential downsides of prolonged fasting.

Throughout the day the body breaks down old and damaged proteins. This creates a need for around 300 – 400 grams of protein every day. But you don’t have to eat that much protein, because the body recycles whatever it can.

But it can’t recycle everything as proteins gets used in metabolism, lost through daily activity like skin cells sloughing, hair growth and cutting, DNA/RNA breakdown, sweat, and urine.

So, we have to eat that which we lose and can’t recycle. If we don’t, the body will “eat” it from muscle and tissues. The body will catabolize itself.

While fasting, the body can only get the amino acids it needs from its own protein. About 85% is stolen from skeletal muscle and the rest from skin.

For example, after you wake up (often >10+ hours of “fasting” since the last meal the day before) muscle protein breakdown (MPB) is 30% greater than muscle protein synthesis (MPS). The body is stealing EAAs for organs to keep you alive. (r)

This is even worse for lean people who will lose an even higher proportion of muscle.

Consistently fasting not only results in the body down regulating muscle protein synthesis (MPS) but other systems too like immune function in order to reduce the amount of EAAs the body needs. (r, r, r, r, r)

I am NOT saying that fasting is bad.

In the context of our modern diet, it is often a very GOOD thing (if you skimmed over the section on Protein and Longevity and the balancing of anabolic and catabolic pathways, this is a good time to revisit that).

What I am saying is that maintaining / building LBM is a very important part of the fat loss equation. And an over emphasis on fasting can be suboptimal. (r)

It’s one reason that a “Protein Sparing Modified Fast” is such a successful approach to rapidly lose fat and improve body composition. It’s basically “fasting” but keeping protein in the diet to preserve LBM.

By keeping 3+ meals of protein, you can stimulate MPS throughout the day, helping to keep a positive nitrogen balance. This helps signal to the body that, although in a steep caloric deficit, to use energy reserves from fat and not muscle.

Further, overdoing fasting can create an adverse psychological relationship with food, one that often leads towards obsessively thinking about food, binge eating, guilt, and overall failure in long term adherence.

Muscle Building: The Other Side of the Body Composition Equation

Just like we don’t want to lose too much muscle while losing fat, we don’t want to gain too much fat when putting on muscle.

This is commonly seen in the bodybuilding world when an athlete does a “dirty bulk” in an attempt to eat ever-increasing amounts of calories to fuel increasing muscle gains.

However, with this approach, muscle isn’t the only thing that hypertrophies – fat does too. And excess fat gain hinders muscle growth via alterations in hormonal states (i.e. reduced insulin sensitivity and decreased testosterone).

But dietary protein appears to have a protective effect against fat gain during times of energy surplus, especially when combined with resistance training.

• Bulking athletes appear to be best served by consuming more than 2.2 g/kg/day and perhaps as high as 3.4 g/kg/day. Whether consuming more than this provides additional benefit still requires investigation (r)
• Consuming less than 1.2 g/kg/day is insufficient in terms of gaining lean body mass (r)

High Protein Diets: Upper Limits?

While there is little research in what is considered “very high” protein diets there are a couple interesting studies that investigated diets with approximately 1.5g/lb and 2.0g/lb:

• 1.5g / lb:

Eating a diet > 4X the RDA resulted in positive changes in LBM among participants without associated gains in fat mass. It was not shown to be dangerous to kidneys or liver. (r)

• 2g / lb:

Consuming 5.5X RDA in a hypercaloric diet showed no increases in body fat. (r)

Consuming 5.5 times the recommended daily allowance of protein has no effect on body composition in resistance-trained individuals who otherwise maintain the same training regimen. This is the first interventional study to demonstrate that consuming a hypercaloric high protein diet does not result in an increase in body fat.

The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals (r)

The evidence suggests that dietary protein may be the key macronutrient in terms of promoting positive changes in body composition. (r)

There is scant information to identify an upper limit to the capacity to metabolize protein by healthy individuals.

Rabbit Starvation

One concern about high protein diets combined with low fats and carbs is “rabbit starvation.”

Two researchers, Speth and Spielmann, looked at some of the literature where people ate more than 45% of dietary energy as protein and noted that some people experienced nausea and diarrhea. (r)

It’s now commonly known as “rabbit starvation” because rabbit meat has little fat content, so trying to subsist on just rabbit meat would lead to a high protein and low fat / carbohydrate diet.

The effects of this kind of diet were studied experimentally in two Arctic explorers who were closely monitored for a year while only eating meat. During this time they remained fit and healthy, besides a brief period when one of them ate only lean meat, estimated around 60% of energy as protein, and developed symptoms of rabbit starvation. These symptoms were quickly reversed when he increased the fat content back to around 75%. (r)

And while some archaeological evidence suggests that hunter-gatherer populations would eat up to, but not beyond about 40% of dietary energy from protein, there still isn’t a “rabbit starvation limit” that has been identified.

Many people, including myself, have consumed intakes of 50%+ of dietary energy from protein for relatively long periods of time without exhibiting these symptoms of “rabbit starvation.”

Part of the reason has to do with adaptive measures to high protein diets and improved efficiencies of amino acid oxidation and urea synthesis. That’s why it’s hard to come up with a true maximum for “rabbit starvation,” if there is one, as it’s a moving target related to individual adaptive capacity.

But at the end of the day, “rabbit starvation” isn’t something I’d worry about. Just as the Arctic explorer did when he started feeling bad, you can simply increase fat intake and quickly reverse symptoms.

It’s Not Just about Body Composition

As I mentioned at the start of this section, improving body composition isn’t just vanity, it’s a means to better health.

Eating a high protein diet significantly reduces several cardiometabolic risk factors like waist circumference, blood pressure, and triglycerides. (r, r)

Improved body composition wards off the threats of sarcopenia that so often appear late in life. (r)

And a healthy body composition helps to simply improve quality of life, making it easier to keep up with kids / grandkids, facilitates better sleep and enhanced energy to enjoy life.

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High Protein Diets: Plants vs Animals

Not all proteins are created equal. Different protein sources have different amino acid contents. Further, different proteins come “pre-packaged” with other molecules that can facilitate or hinder the quality of that protein.

Plants vs Animals: Complete vs Incomplete Proteins

Complete Proteins

Animal proteins are called “complete” proteins because they contain all the amino acids in sufficient quantities.

Not only are animal proteins complete proteins, but they are also high in the branched-chain amino acids (BCAAs), which account for about 50% of all the EAAs that you need.

EXCEPTION: An "exception" to animal protein being complete proteins is collagen. It's lacking in tryptophan, which is one of the nine EAAs. It's also poor in BCAAs. However, it is rich in glycine, proline and hydroxyproline. Moreover, in nature, collagen consumption would only occur when eating an animal, which would provide complete protein. But I thought it was important to mention here as some people supplement with collagen protein, and on its own, it's an inadequate protein if relying on it as a main protein source.

Incomplete Proteins

Most plant-based proteins are deficient in one or more amino acids and are thus considered “incomplete” proteins.

An analogy helps put this in perspective.

Imagine you need to build a house, and you have 9 essential materials. There are 11 other materials that are needed, but they are less essential because if they are missing you can just use one of the 9 in its place.

Now imagine you don’t have enough of 1 of the 9 essential materials. And that missing material is critical in putting the roof on. Well you are going to have holes in your roof, and your house is likely going to be weak, easily damaged, and perhaps not functional at all.

This is a basic analogy of incomplete proteins.

Incomplete proteins are inadequate with regard to at least 1 of the 9 EAAs. These limiting amino acids act as a “bottle neck,” which impede protein synthesis.

Most plant-based proteins are incomplete proteins.

Seeds like wheat, rice, and nuts are all poor in lysine.

Beans and legumes are poor in the sulfurous amino acids, methionine and cysteine.

Corn is poor in tryptophan.

So, say nuts were your main source of protein. You could be in serious danger of lysine deficiency, which can cause problems with protein synthesis. And because we need to make proteins for nearly every process in every cell of our bodies, this can have serious ramifications.

EXCEPTION: Two plant-based protein exceptions are soy and quinoa. They are low in lysine, threonine, and the sulfur amino acids, but have enough to get classified as complete proteins.

Conditionally Essential Amino Acids

To extend the analogy just a bit further, imagine the house you built with the 9 essential materials caught fire, and a hole was burned through the roof.

Under certain circumstances (growth, stress, illness) materials that weren’t essential become essential to fix the hole in the roof.

These “materials” (amino acids) are considered “conditionally essential.”

Here’s a real-life example relating to this fire scenario. Burn victims need significant amounts of glutamine to heal. In this situation glutamine becomes essential because the body can’t make enough on its own.

In this situation glutamine (which normally isn’t an essential amino acid) becomes essential, and is therefore classified as a conditionally essential amino acid. (r)

Mix and Match Incomplete Proteins to Create Complete Proteins

While plants use the same 20 amino acids to build their proteins as animals do, most have at least one if not several limiting EAAs.

Because these sources don’t provide “enough” of an EAA, it’s important they are combined with other protein sources to avoid a deficiency.

If combined with adequate meat, amino acid deficiencies can largely be a non-issue. Where this becomes risky is if people do not eat meat, and thus have to combine plant-based sources to try and ensure they get adequate amounts of all the EAAs.

For example, a grain—legume combination like beans and corn, or rice and soybeans can help avoid a deficiency.

However, even with this strategy these combinations tend to be low in leucine no matter how you mix and match. And this issue isn’t easily overcome without supplementation. One solution would be to eat a whole lot of corn (but that’s a whole other problem).

Another issue with relying on plant-based proteins that is often overlooked is the huge metabolic risk this poses.

Relying on plant-based protein results in eating 25-35% more calories. Usually carbohydrate-based calories. And when you have a diet with a high carbohydrate load (often in caloric excess) and poor quantities of BCAAs, the result is often poor body composition and a metabolic disaster.

⬆ Carbohydrate + ⬇ BCAA = Poor Body Composition / Metabolism

Protein Quality: DIASS

A rating system used to evaluate protein quality is the DIASS — Digestible Indispensable Amino Acid Score.

It rates protein quality based on digestibility, absorption, and ability to make other proteins.

The DIASS of meat and eggs score the highest, while cereal grains score the lowest.

One reason is digestibility.

Animal-based proteins have digestibility over 90%.

Plant-based proteins have digestibility between 60-80%.

If we look at PDCAAS (Protein Digestibility Corrected Amino Acid Score) where a maximum score is 1.0, animal meats like beef score 0.9 compared to 0.5-0.7 of most plant foods. (r)

Plant-based proteins are considered low quality because they have weak amino acid profiles, poor digestibility rates, and come “pre-packaged” with antinutrients that interfere with digestion and absorption.

Protease inhibitors like trypsin inhibitor, phytates, and tannins tag along with these plant-based foods making it difficult for the body to digest and extract nutrition.

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Meat: Raw vs Cooked

By now you’ve probably surmised that I think most of the protein we eat should come from animal-based foods.

Humans have been eating meat for millions of years. Even before the advent of fire (estimated around 400,000 years ago).

And while the ability to control fire enabled humans to eliminate parasites from food, keep warm in cold climates, and offered protection from predators and insects, it wasn’t a necessary component to our meat-based diet. (r)

So I don’t think the question is “if we can” eat raw meat, Arctic people do, sushi and steak tartare are common dishes, and my steaks are so rare that many people consider it “raw.” But I think the question people wonder is “if we should be” eating our meat raw.

There is some evidence that the advent and subsequent use of fire for cooking enabled evolutionary adaptations. It may have helped further shrink the intestinal tract, which feasibly could allow an even bigger brain. Some liver enzymes suggest adaptation to cooking. Our jaws have shrunk compared to our earlier homo sapien ancestors.

Unfortunately (like most things in nutrition) there is no clear cut “winner” to the cooked vs raw debate. There are potential pros and cons to both.

Bacterial Contamination and the History of Raw Meat

The obvious negative of raw meat, especially meats like chicken and pork, is that bacterial contamination can be an issue.

When early humans left the trees for the grasslands, we were untrained and ill-equipped hunters. We were also easy prey of fierce, well-trained predators. So, we did the obvious, we scavenged.

In the early goings, humans were likely carrion feeders which means we ate on dead and rotting flesh. We’d let the professionals do the killing and we’d hurry in for the scraps and return to safety.

Although we weren’t great killers in the early get-go our stomachs evolved through natural selection to do pathogen fighting for us. The strong acid in our stomachs killed off pathogens that resided in the rotting animals we scavenged, and it also enabled improved digestion of meat.

Acidic stomachs separate carnivores from herbivores. The acid filters out the bad pathogens while facilitating digestion into the small intestines. Baboons for example, who are considered one of our closest relatives, have stomachs that are about 1000X less acidic than ours.

But it’s common for people who eat a more Standard American Diet (SAD) to have poor HCl production which may not kill microbes as effectively, thus making consumption of raw meat riskier.

Denatured Proteins

One of the chief concerns about cooking meat is that the proteins may get denatured.

This means that the three-dimensional structure of the protein changes from its native conformation. If these tertiary and quaternary structures of a protein are altered by physical factors like high temperature, changes in pH, or even variations in sodium concentration gradients, the protein is considered denatured and loses its native biological functionality.

And depending on what kind of meat, cooking method, temperature, etc…this is likely happening to varying degrees.

Meat Denaturing

For example, collagen, the connective tissue that separates bundles of muscle fibers, turns into gelatin (140 – 170°F).

The protein inside the muscle fibers like myosin can also be denatured around 120°F and myoglobin 140°F (myoglobin turns from red to brown/tan color, hemichrome) .

But what is unclear is whether this is good or bad. This denaturing is going to happen in the stomach regardless.

And often when these proteins are denatured by cooking, pepsin, an enzyme in the stomach, can digest them better.

However, the cooking can destroy the natural enzymes in the raw meat that can aid in digestion as demonstrated by Alexander Ugolev.

Frog Experiment

A Russian scientist, Alexander Ugolev, did an experiment with 2 frogs – one cooked and one uncooked. He then placed each into a cup that was filled with a carnivore’s stomach acid, HCl.

The uncooked frog completely dissolved.

The pre-cooked frog remained mostly intact with only moderate changes to its surface.

The reason is that the cells in the raw frog underwent “autolysis,” which means “self-destruction,” when put in the HCl. All living cells do this when exposed to certain conditions. In the case of the raw frog, when the HCl invaded the cells it caused the release of enzymes that initiate autolysis and self-digestion.

Combination of HCl + Frog’s Natural Enzymes = Complete Digestion

In the case of the pre-cooked frog, it’s natural enzymes that would initiate autolysis were destroyed in the cooking process. It lost its ability to “self-digest.” So, the HCl acted on the surface tissues, but internally wasn’t completely digested.

Dairy Denaturing

We see a similar issue with dairy.

With pasteurization of dairy, the “pro” is the “con,” meaning heating the milk kills bacteria, both the potentially contaminated microbes as well as those that are beneficial and aid in digestion.

Egg Denaturing: Yolks vs Whites

The egg beautifully demonstrates the potential “pros” and “cons” of cooking.

Roughly 60% of the protein in an egg is in the egg white.

These proteins are called albumen, and the most abundant one, ovalbumin, makes up about half of the egg white protein. In its raw form ovalbumin blocks our natural protein-digesting enzymes.

Another egg white protein called avidin binds to biotin, an essential B vitamin, and prevents the body from absorbing it.

Luckily, both ovalbumin and avidin denature with cooking (at 176°F), which increases ovalbumin’s bioavailability and inactivates avidin’s biotin-binding property.

These represent the benefits of protein denaturing.

On the flip side is the egg yolk.

The 40% of an egg’s protein in the yolk is full of nutrients, some of which may get lost or damaged in cooking.

For this reason, I recommend cooking egg whites, and eating the yolks however you prefer them, but ideally a bit runny for maximum nutrition.

Raw vs Cooked Recommendations

Unfortunately there is not a substantial body of evidence to guide us in many of these raw vs cooked decisions.

There are studies that show that cooking can actually increase bioavailability, and there are studies that show that cooking can destroy enzymes and inactivate vitamins.

There are some people who swear by and thrive on eating just raw meat. They often note that it wasn’t until they went raw did they achieve complete remission of health issues. They commonly report that eating raw meat reduces the body’s digestive load and thereby makes them feel lighter, improves their energy, and they experience a feeling of true satiation and nourishment.

But these case reports are anecdotal and limited in number.

If you decide to test the raw route, I recommend protecting yourself from parasites and pathogens by buying your meat from reliable sources. Freezing the raw meat and thawing it in the refrigerator for a day or two before eating can also help protect the meat.

For many people, the stomach needs to regain its natural acid producing capacity, but once it does it has increased abilities to kill parasites and pathogens as well as improved efficiency for digesting meat.

My general recommendation is to cook your meat how you enjoy it.

When I first started eating just meat, I liked my steaks cooked about medium. As months went by, I started enjoying them more and more rare. Now I just like a quick sear and the inside basically raw.

With beef, if it has contamination, it starts on the outside, so a sear can act as a “safeguard.” But this is also why I cook my ground beef more thoroughly as the increased surface area increases risk of contamination. I cook my chicken and pork thoroughly. Seafood is variable.

It’s worth noting that one thing we lost that our ancestors likely got via eating raw meat is sodium and water.

In the US, meat is hung for several weeks before it goes to market. This allows for blood to be extracted (the “red juice” in meat is myoglobin, not blood). So, a 100,000 years ago when a hunter made a kill, the meal had more sodium and water from the fresh meat. This sodium and water content is lost in our meat today.

Many animals get almost all the water and sodium they need simply with the meat they eat. Not so with most our meat eating today (unless you are hunting and eating it right then and there). It’s one reason why salt and water are two things I “supplement.”

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High Protein Diets: Conclusion

We’ve gone through a lot here. If you made it through, congrats, you know more about protein than most dieticians and even doctors.

But more importantly, I hope you can now make more informed decisions about this very important macronutrient to achieve whatever your health goals might be.

If you had concerns about eating “too much” protein, I hope this helped to alleviate these fears in Part 1. Let’s recap.

Part 1: Dangers of a High Protein Diet – Recap

First, we saw how steak does not equal cake. In fact, the evidence suggests that protein does not increase the rate of GNG, and the Insulin:Glucagon ratio controls glucose production and ketogenesis, and this ratio doesn’t change much in low/no carb dieters with variable protein consumption.

While there are compelling arguments that protein does increase glucose oxidation in no/low carb dieters and this can decrease ketone production, this is often a non-issue with respect to most people’s health objectives.

Secondly, we reviewed protein consumption as it relates to gout, and saw that a diet high in purines (i.e. meat) isn’t the primary driver of gout, rather dysfunctional clearance and subsequent buildup of uric acid as a result of elevated insulin and impaired kidney function; a situation exacerbated by excessive fructose and alcohol consumption.

Thirdly, after discussing impaired kidney function and its role in gout, we talked about the myth of too much protein being hard on the kidneys. Most kidney disease is due to diabetes and hypertension – a carbohydrate problem, not a protein issue. The most reliable way to injure the kidneys is consuming a diet high in sugar/carbs inducing chronic elevations in blood sugar, insulin, and blood pressure.

Fourth, we discussed the common fear of too much protein causing bone health issues due to its acid content. Yet time and again, when researchers try to find a link between high protein diets and an increased risk of bone fractures, not only do they not find a correlation, but they find that protein intake is positively associated with bone mineral density.

Fifth in the fears around protein, we looked at longevity, specifically discussing common villains like mTOR and IGF-1. We went into detail of what I think is one of the critical keys to health and longevity – the balance between anabolic and catabolic states.

Lastly, in wrapping up fears around protein, we discussed amino acid balances, specifically methionine and glycine. Here we saw how the body can use, eliminate, and recycle amino acids in an intricate system that is designed to keep homeostatic balances.

Part 2: Protein –The Most Essential Macronutrient – Recap

Next, we looked at the flip side of the coin – the essentiality of protein. We discussed how the real fear around protein shouldn’t be eating too much, rather not consuming enough.

First, we discussed this in the context of the “Protein Leverage Hypothesis,” where researchers hypothesized that protein could be the key to solving obesity and the common metabolic diseases of today. In essence, if we aren’t meeting our protein needs, we will overeat in an attempt to meet them, and this overeating compounded over time is causing our most common health epidemics.

While not discussed in the original Protein Leverage Hypothesis, we talked about how carbs and certain fats can further exacerbate the need to continuously overeat, overriding our natural satiety mechanisms.

We also related the Protein Leverage Hypothesis to a species and evolutionary perspective. Humans have been eating meat for millions of years. Meat-based, high protein diets are what allowed us to dispense the large fiber digesting guts of our primate ancestors in favor of massive, energy-hogging brains. And if we look past the cultural conditioning of the last century, and even further back past the industrial and agricultural revolutions, we’d find that meat is the foundational, baseline, food for humans.

Next, we looked at protein’s role in body composition – burning fat and building muscle, and saw how the “protein advantage” can help people reach their individual goals faster and more easily. We also discussed fasting as well as a word of caution around overdoing abstinence of food, notably protein.

Finally, we discussed how not all proteins are created equal. Specifically how plant-based and animal-based proteins differ in quality (DIASS). We also discussed how protein from the same food can differ based on cooking, and examined the pros and cons of cooked vs raw meat.

Now to officially wrap up this post on protein I want to discuss one last thing…

High Protein Diets: Final Thoughts

Do we need to revise the RDA on protein?

Pragmatically, protein is the most essential macronutrient. The origin of the word comes from the greek “protos,” which means “first,” reflecting protein’s supremacy in human nutrition (finally – years of ancient greek in high school pay off).

We all have basal metabolic requirements of protein from obligatory nitrogen loss. But just because we can survive on a certain “bare minimum” doesn’t mean we should.

But this is basically where RDA recommendations come from. It’s the amount we need to meet minimums to avoid a general population from getting sick.

They recommend around 50g protein/day (0.8 g/kg). (r)

For most people this is under the “protein floor” of 15% as discussed in the protein leverage hypothesis.

And if this hypothesis pans out, the RDA’s recommendations are responsible for obesity and disease, and these recommendations should be revised.

The current RDA recommendations are even worse for certain demographics that need more protein like sedentary populations, the elderly, pregnant women, and rapidly growing youth. (r, r, r, r)

And while current recommendations do at least recognize that different people need different amounts of protein, I think these recommendations are woefully inadequate.

My High Protein Diet “Baseline” Recommendation

It’s impossible for me to recommend a certain amount of protein.

We have different ages, genders, health histories, goals, activity levels and lifestyles.

However, a number that I am comfortable suggesting as a guideline for most healthy adults is around 1g protein / lb of bodyweight (2.2g/kg).

This is a common baseline number for many in the bodybuilding world. It represents what I consider a “minimum” for “maximum” muscle building. While vastly oversimplified, I’ve found this to be a good rule of thumb.

It’s a number that meets almost anyone’s protein requirements. It’s a number that helps optimize building / maintaining lean body mass as well as satiety for fat loss and prevention of overeating. It’s a number that will help balance the anabolic / catabolic relationship (discussed in Part 1) that I believe plays a central role in long term health and wellbeing.

Tailoring Intake from the Baseline

Undoubtedly, for a specific person / goal, more or less protein may be more or less optimal. Many people who have body composition as a primary goal may very well meet their goals faster and more easily with even higher protein.

For example, I like to eat around 1.5g/lb or even higher if doing a bodybuilding-style fat loss cut. In this situation, when in a prolonged caloric deficit, not losing muscle is a top priority and very high protein helps prevent loss of LBM, helps with satiety, and even offers further help via the “protein advantage” (discussed in Part 2).

I think the elderly should error on the high side with protein too (~1g/lb).

Sarcopenia, impairment of physical function combined with loss of muscle mass, is the primary age-related cause of frailty leading to disability, nursing home placement, fractures, falls, hospitalizations, reduced quality of life, and premature death. Not a minor issue.

The older we get the harder it is to build and maintain muscle mass. To combat this anabolic resistance, we need to eat more protein to stimulate MPS. But just the opposite tends to happen as we age. We eat less protein.

In the US more than 40% of men and 55% of women over the age of 50 have sarcopenia – and the research is clear – low protein intake is associated with frailty and worse physical function than a higher protein diet. (r, r)

Luckily, animal protein looks to be the solution. (r)

On the flip side, some people may feel or do better in deeper levels of nutritional ketosis, and may see more optimal results (as defined by their individual goals, feeling, and function) keeping their protein around 0.75g/lb.

What I recommend is use 1g/lb as a baseline and experiment from there what works best for you and your life.

I want to thank you for taking the time to read this rather long article. I hope it provided the value you were looking for.

If interested in learning more about the other macronutrients, I would recommend starting with this post on carbohydrates.

If you want to know how all the macronutrients fit into the big picture of health and fitness, I would recommend watching the Meat Health Masterclass: