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High-Protein Diets
Is More Protein Actually Better?

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High-Protein Diets: Is More Protein Actually Better?ShareFollow us 261.1k

Quick Summary tl;dr

  • There is no clear consensus on what defines a “high-protein” diet. Often, “high-protein” diet in studies is what most people would consider a normal protein diet.

  • There are multiple ways to measure protein intake, including the percentage of calories from protein or grams of protein per pound body mass.

  • Being lean, active, and caloric restriction can increase your absolute protein needs.

  • High-protein diets, within reason, do not harm healthy kidneys, bone health, or shorten lifespan.

  • Protein quality matters. This can be assessed by PDCASS and DIASS scores. In general, animal proteins are of higher quality than plant proteins.

  • There is no good reason for most people to be targeting extremely high protein intakes.

Table of Contents

“High-protein” diets are all the rage right now. And with all the enthusiasm there is an equal amount of confusion. How much protein should I eat? Can too much protein be harmful? What are the best sources? In this article, we will try to clarify the confusion.

High Protein is Poorly Defined

The “high-protein diet” is poorly defined. For example, the U.S. Food and Drug Administration has set the Daily Value for protein at 50 grams per day on a 2,000 kilocalorie diet. That’s only 10% of calories from protein. If we were to use these recommendations, the average American adult man or woman consuming 16.3% and 15.8% of calories from protein, respectively, would already be eating a high-protein diet ( CDC data).

The Dietary Reference Intake for protein is similarly low at 0.36 g/lb of body weight. For a 160 person, that is 57.6 grams of protein. In other words, a single 6 ounce cooked chicken breast is supposedly sufficient to supply a fully grown adult male with all his protein needs (USDA Food Central).

These values are generated based on the amount of protein required to protect against overt nutrient deficiencies. They are not meant to suggest a recommended protein intake for optimal health in any individual. Nevertheless, these values — especially 0.36 g/lb of body weight — are important to acknowledge in any discussion of high-protein diets because they serve as the reference point in many studies for how “high-protein” is defined in the scientific literature.

As a result, some studies use values similar to 0.36 g/lb as a control. And, consequently values such as 0.5 g/lb body weight ( Soenen et al, 2012) become “high-protein.” However, on the other end of the spectrum, some studies will use the term high-protein diet to refer to diets containing 1.4 g/lb lean body weight. ( Helms et al, 2014) (Note: Lean body weight refers to total body weight minus body fat. You can learn more about calculating body fat here.)

The enormous variation in how we define “high-protein” has led to tremendous confusion in the field. In six words: high-protein diets are poorly defined.

By Daily Reference Intake standards, a single chicken breast can meet the protein needs of a fully grown man. Is that reasonable?

Percentage of Calories vs. Grams per Pound

Now, while our goal is not to define what “high-protein” means, it will be useful to distinguish between the two most common ways to measure protein intake. These are:

  • (i) % Calories from protein
  • (ii) Protein consumed per pound of body weight.

Each of these metrics has their benefits. % Calories from protein provides an energy intake control, as in research settings. For example, if a study compares a 15% protein diet to a 30% protein diet, then 15% of dietary calories needs to be adjusted for by lowering fat and/or carb calories.

Protein per pound of body weight is perhaps a better measure in free-living individuals. 1 g/lb protein will almost certainly meet most people’s needs, and yet could contribute 15% or 30% of a person’s total intake depending on their energy needs.

The central point here is that, again, defining “high-protein” is tricky. Not only do we lack a consensus threshold to determine if a diet is “high-protein,” but we are often using entirely different measuring sticks altogether.

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Benefits of High Protein Diets

Satiety per Calorie: High Protein Diets Will Keep You Full For Longer

With those caveats in place, let's turn to the purported benefits of high-protein diets, beginning with satiety. It is argued that eating a high-protein diet will make you feel full, helping to naturally limit energy intake. In other words, protein-rich foods have the highest “satiety per calorie.”

In general, we tend to agree with this point. Here’s a thought experiment: imagine eating a 6-jumbo egg-white omelet (protein), or sipping one tablespoons of olive oil (fat), or eating one banana (carbs). Each of these options contains approximately the same calories but one is obviously more filling than the others.

That said, the “satiety per calorie” concept misses an important point: eliminating sugar, refined carbohydrates, and processed foods from the diet are more potent tools for controlling overeating. In fact, I’d wager that if you simply added a donut to your egg-white omelet breakfast, you’d be hungrier in three to five hours, not less. (Side bar: That's rhetorical. Don't try this at home kids!)

Simply put, when it comes to controlling hunger and cravings, it’s less about what you do eat than what you don’t.

Otherwise stated, and to pose an ironic analogy, when it comes to controlling overeating, consuming a clean diet free of sugar is the sundae, and eating high-protein is the cherry on top.

Higher Thermic Effect of Food

It is also argued that protein has a higher thermic effect of food (TEF) than fat or carbohydrates. At some level, this is true. For example, one meta-analysis ( Eisenstein et al, 2002) calculated that TEF as % of total energy burned could be calculated using the following equation:

TEF (%Energy intake) = 0.132P + 0.051F + 0.054C, where P, F, and C are grams of dietary protein, fat and carbohydrates.

The Thermic effect of food can be calculated as: TEF (%Energy intake) = 0.132P + 0.051F + 0.054C, where P, F, and C are grams of dietary protein, fat and carbohydrates.

Clearly, the coefficient of 0.132 on protein is the largest number, suggesting that TEF is greatest if you eat more protein. That said, the absolute increase in TEF is pretty small when you do the math. On a 2,000 Calorie diet, doubling protein intake from 15% to 30% only increases TEF by about 23 Calories per day.

The magnitude of this effect is relatively small. By comparison, the Framingham Food Study and follow-up analyses show trading carbohydrate calories in for fat calories, while controlling protein at 20% of caloric intake, increased total energy expenditure by 200 - 300 Calories per day. (NN Blog on CIM)

Thus, one could argue the metabolic benefits of substituting carbs for fats, in terms of energy expenditure, are an order of magnitude greater than those of increasing percent calories from protein under some circumstances.

And, as an added nuance, newer research suggests that the presence of insulin resistance decreases TEF by uncoupling insulin from the upregulation of thermogenesis in muscles. ( Habtemichael et al, 2021) Those are a lot of big words, but this implication is that your metabolic health also determines your TEF, and perhaps does so to a greater extent.

So how do you achieve metabolic health? That’s a big question. But it’s worth mentioning a randomized crossover trial demonstrated that decreasing carbohydrate intake reversed metabolic syndrome far more effectively than decreasing fat intake, even when both total calories and protein were controlled. (NN Blogs on Mets) This study didn’t test whether TEF increased on a low-carb diet after reversal of metabolic syndrome, but it is an interesting hypothesis!

Again, when it comes to energy expenditure (and possibly TEF too), metabolic health may be the proverbial ice-cream sundae, and high-protein is the cherry on top.

Protecting Muscle During Caloric Restriction

One circumstance under which increasing protein intake is certainly beneficial is when a person is undergoing forced caloric restriction. This could be an obese participant in a research study, or a body builder prepping for a contest, or any circumstance in between.

When your body is deprived of energy, muscle tissue can get broken down to make glucose. This is especially true when you are not fat-adapted because the body will be more dependent on glucose and will not benefit from the muscle-protecting effects of ketones.

In fact, if you are a lean and highly trained athlete in and in a meaningful caloric deficit (e.g. preparing for a body-building competition), some research suggests consuming as high as 1.4 g/lb of lean body mass could be beneficial ( Helms et al, 2014). At 12% total body fat that would equate to ~1.6 g/lb, which is “high-protein” equal to 440% of the dietary reference intake. That said, newer literature and current recommendations for weight loss in athletes suggest intake of 1 g/lb during weight loss is plenty. ( Hector at al, 2018)

The extreme example of ~1.4 g/lb lean mass is helpful in that it sets an upper bound for where the purported benefits of high-protein may end. That said, data from a recent meta-analysis suggest that eater higher protein can increase lean mass up to the highest level tested (~1.6 g/lb) and supposedly without limit. ( Tagawa et al, 2020)

But there’s always an added nuance. For example, this analysis also found that increasing protein intake beyond a certain point was associated with a decrease in lean mass when individual were not resistance training and when body weight was controlled.

The bottom line is that protein needs are not only dependent on gender, age, and size, but also protein quality and other environmental factors, like whether you’re exercising.

Functionally speaking, and as relates specifically to weight management and body composition (not health per se), these are important factors to keep in mind:

  • The more active you are, the more protein you will need. Being more active will increase your protein needs in g/lb body weight but decrease your % Calories from protein as your increased overall energy needs will likely outweigh your increased protein needs.
  • The higher your body fat, the less protein you will need in terms of g/lb from protein. Protein is required by lean muscle tissue. So, if less of your total body mass is lean mass, you will need less protein per pound of body weight.
  • If you are restricting caloric intake, your protein needs will go up to protect against loss of lean mass. The leaner you are, the stronger this effect might be as you have less local fat tissue to fuel muscle.

Keep these questions in mind when you’re determining how much protein you need.

  • Are you active?
  • Are you lean?
  • Are you restricting calories?

High-Protein Diets: Is More Protein Actually Better?

Myths About High-Protein Diets

High-Protein Diets Harm The Kidneys

The notion that a high-protein diet could put strain on and harm the kidneys has always been theoretical and never really materialized in clinical trials including persons with baseline normal kidney function.

Furthermore, a systematic review and meta-analysis of 28 trials including 1,358 participants comparing a high-protein diets (defined as ≥ 0.7 g/lb body weight or ≥ 20% energy intake or ≥ 100 g protein/day) to lower protein diets in adults without kidney disease found that “high-protein intakes do not adversely influence kidney function.” ( Devries et al, 2018)

That said, it is important to caution that, in patients with pre-existing kidney disease, high-protein intake can be contraindicated.

Furthermore, because intakes at the extreme end of high-protein diets have not been rigorously tested in large-scale trials, one can’t rule out the possibility that there is a threshold above which high-protein diets could theoretically be harmful to the kidneys of even healthy people.

Absence of evidence is not evidence of absence. But neither does the literature doesn’t support the claim that high-protein diets harm the kidneys.

High-Protein Diets Harm Bones

This myth can be busted quite quickly. The National Osteoporosis Foundation itself conducted a systematic review of 16 randomized controlled trials and 20 perspective studies and found, “Current evidence shows no adverse effects of higher protein intakes.”

Protein, in fact, is essential for bone health, and low-protein diets confer a higher risk of developing low bone mass (especially in the spine) than do high-protein diets. ( Shams-White et al, 2017)

High-Protein Diets Shorten Lifespan

The notion that high-protein diets shorten lifespan usually comes down to discussion about the protein complex, mTOR. On the one hand, mTOR activity signals growth. Stimulation of mTOR by protein is necessary to build healthy lean muscle mass. On the other hand, some people fear mTOR activity because inhibiting mTOR activity in animal models, such as yeast, fruit flies, nematodes, and mice, leads to lifespan extension. ( Saxton et al, 2017)

That said, it is a huge leap of logic to suggest that eating high-protein shortens lifespan in humans. There is no evidence in humans that high-protein diets shorten lifespan or that low-protein diets improve longevity.

To try to label mTOR as either good or bad misses critical nuances about this important protein complex that are beyond the scope of this blog. But, if you want to read more about “mTOR mysteries,” specifically as relates to brain health and cognitive longevity, you can see  this review.

Finally, high levels of lean muscle tissue are an excellent predictor of longevity in humans, so eating a low-protein diet might even be detrimental to living a long and healthy life.

High-Protein Diets: Is More Protein Actually Better?

Protein Quality Matters

“How much?” is one question. “What source?” is another.

Not all protein sources are created equal. In general, animal proteins are more available to the body and contain a better composition of amino acid building blocks for constructing lean tissue.

The PDCAS Score

One measure of protein quality is the PDCASS score, which stands for protein digestibility corrected amino acid score. Using the PDCASS method, proteins are given a score ranging from 0.0 to 1.0, with 1.0 being an ideal protein. Most animal proteins score a 1 or near a 1. For example, milk, eggs, beef, fish, pork, and chicken all score 1.0. By contrast, chickpeas score a 0.74, peanuts or wheat bran score a 0.5, and almonds score a 0.4.

The DIASS Score

A newer method for assessing protein quality is the DIASS score system, which stands for Digestible Indispensable Amino Acid score. DIASS score is considered a better metric than PDCASS, for reasons you can read about here, but isn’t as popular because fewer foods have been given a DIASS score. Still, we see a similar pattern where animal proteins are superior. Foods given DIASS scores of 1.0 or higher are “excellent” proteins, those given scores of 0.75 - 0.99 are “good” proteins, and those that receive scores of <0.75 get “no protein quality” claim.

Using DIASS, whey, beef, lamb, pork, chicken, fish, and eggs are “excellent,” whereas spinach, beans, tree nuts, and many vegetables get “no protein quality” claim.

Using DIASS scoring, beef, lamb, pork, chicken, fish, and eggs are “excellent,” whereas spinach, beans, tree nuts, and many vegetables get “no protein quality” claim.

Plant Proteins - Are They Good?

That said, among the plant proteins, soy protein concentrate scores a 1.0 on PDCASS and 0.9 on DIASS, which makes it a “good” protein source as far as plant-based proteins go.

Pea protein similarly scores a 0.89 and 0.82 on these metrics, so is also a “good” protein. Soy protein is also considered a “complete protein” because it contains all nine essential amino acids — protein building blocks that the body can’t produce from other amino acids. Pea protein falls just shy of being a complete protein because it’s low in methionine.

Admittedly, even protein digestibility and bioavailability scores still don’t reveal a complete picture. Different protein sources have different compositions of amino acids, just like different Lego sets include different Lego pieces. In our opinions, it makes more sense to eat animal protein to build an animal than to eat plant protein to build an animal.

That said, it is possible to eat a healthy vegetarian diet. And, if you do choose to make this your lifestyle, perhaps consider reading more on PDCASS, DIASS and protein quality metrics so that you can make informed choices about the best protein sources available to you.

Should I Be Following a High Protein Diet?

The notion that trading protein for carbs or fats is better for health is overly simplistic. First, we don’t have a good definition for “high-protein.” If we are using 0.36 g/lb as our reference, then a high-protein diet of 0.7-1.0 g/lb probably is better for health. But it does not follow that more protein is always healthier. In my opinion, there is no good reason for most people to be targeting extremely high protein intakes.

Building on that point, the discussion of extremely high-protein diets usually focuses on optimizing body composition at the extreme limits of lean.

Most people are not competitive body builders. And most people (I hope) are more interested in being healthy than shredded to 4% body fat, which is not necessarily healthy. Trust me. I’ve been there. Unfortunately, this nuance gets lost in discussions about high-protein diets, which the focus primarily on body composition.

In closing, I personally am for high-protein diets, within reason. The only purpose of this blog was to prompt you to ask that very question: what does “within reason” mean to you?

Is a high-protein diet actually better? Scientific reason, not click bait.

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Comments (15)

Is it healthy enough to consume a conventional chicken breast(that is GMO free though) instead of an organic one as chicken breast barely has any fat and contains mostly protein? Since one is twice as expensive as the other, would like to get your opinion on whether an organic chicken breast is worth the extra price.

I heard several people having sluggish bowel movements(not constipated though) when they consume high quality pea protein(with no additives) too, even if it is just 1 scoop per day. I am myself planning to consume protein powder to up my protein intake but little worried after hearing these stories. So I would like to know your thoughts and research on this.

It's definitely possible. I don't think I could identify a specific single cause of pea protein-induced constipation, nor do I think it's a common side effect in those without a history of CC, IBS-C or other form of constipation. However, if you do choose to add a protein supplement, try to get one that includes only the protein of interest with few additives. You might also consider Whey protein as a higher quality alternative with a higher DIASS score.

I feel so confused. So many people are now recommending low fat, high protein keto and I'm not sure what to do. Can a person like me (relatively fit with some extra weight, 155 lbs, about 28% body fat) benefit from high protein? I've been stuck at the same weight for the last 3 months and I always feel hungry but I don't think I've been eating too much fat at 1300 calories. My fitness coach told me my body won't be able to use too much protein but what happens to it if I eat it and can't use it? Thank you for your time!

"Low fat, high protein keto" is an oxymoron. In other words, it doesn't exist. The caveat to that is you could get into ketosis while being low-fat high protein is you were severely calorically restricted, but that's not sustainable nor is it healthy. Biggest Loser participants may fall into that category and, generally speaking, they don't end up so well. Ever seen a 5-year reunion? You know why not? Anyway, 1300 kCal is pretty low. I'd perhaps explore with your coach the possibility of increasing calories from fat and/or protein, depending on what your protein intake is currently. As explained, "high-protein" isn't well defined. If you're eating 0.7g/lb and you want to go up to 1.1g/lb or something, that's probably fine. But I definitely do not recommend making your diet a low-fat egg-white, tuna steak, chicken breast, dressing-free salad style diet in the hopes that will make you lose weight and sustain that weight loss long-term. As for your question about what happens if you consume excess protein, your body can deaminate the amino acids and use the hydrocarbons in the protein to make glucose. That doesn't necessarily mean your fasting blood sugar will increase, although it can, not is this necessarily a bad thing. But protein isn't just some free macronutrient either. And, really high levels of protein will kick you out of ketosis. I don't have specific advice for you because I don't know your specific case. What I will say is, if I were you, I would consider the possibility that "I" may be underrating calories and, if it seems reasonable given the amount of protein "I" was currently eating, "I" might bump up the protein and/or fat and just watch and see how my body responds, then adjust. Something tells me you aren't eating 250 grams of protein per day, which is what some people take high-protein to mean, and very few benefit from levels that high.

Thank you so much for getting back to me. My coach actually agrees with you with regards to calories. I think it's this whole calorie fear because I was always told that I need to be watching them. I'm slowly getting there but it really messes with your brain and it takes time to start eating "normal" again.
Protein... I'm at about 0.5 g/lb so I'll try to go for 0.8-1.0 g/lb and see how that goes. Some people on Instagram are doing high protein with 200-300 grams and that's not something I could do. What a relief that I don't have to eat just egg whites and dry tuna. Thanks again, really appreciate your help!

Of course Hannah. And I get it. Even when you know it's not necessarily healthy or adaptive, getting away from a calorie mindset can be really hard because of all the messaging we internalize over the years. If you hear a message enough, you'll start to believe it emotionally, even more so than consciously. Does that make sense? For you, I would guess it makes sense to count for now to focus on intentionally boosting because when you see that 1,500 number, then 1,600 etc. and realize, "wait, I'm not getting fatter, I'm getting stronger and have more energy and feel better" then you start to internalize a new message. None of this is easy, but good on you for investigating and best of luck!

I tried high protein before keto and it wasn't easy. Based on my macros I ended up doing 30-50 grams of fat for weight loss and that meant little to no added fats. Whenever I increased fats I started gaining again. The meals weren't palatable without fats and it was expensive to maintain that lifestyle. I'm now keto at 90-100 grams of protein and 110-130 grams of fat and still losing weight although it's slow.

Slow and steady wins the race Ann-Marie. A diet with 30-50 grams of fat sounds depressing to me, ha. That's like half an avocado and a small handful of macademia nuts then all you get is cod, chicken breast, and egg whites. [cry emoji] Glad you've found something that seems to be working better. If you're low-carb then you sound like you're in the ~1500-1600 kCal range, which is probably reasonable for weight loss. Wouldn't recommend going lower in general unless you're really tiny. Enjoy some yummy (and fatty proteins!)

Right!? Thank you! That's what I think about it now. Sometimes I get stuck for a few weeks but then start losing again. I've read somewhere that this may have to do with the monthly cycle which makes sense. I stopped following another keto website right after they switched to high protein and started recommending 20-50 grams of fat for weight loss. I know that is not sustainable and I don't understand how that's even keto. Surely it's more than just about the production of ketones.

The only way to be low-fat and low-carb is pretty much to starve yourself. For a short period of time, that's fine. You can fast for several days (conservatively speaking) and be fine. But, just like fasting, you can't do it forever. "It's sustainable until it isn't" -- a stupidly obvious statement that I actually think fewer people appreciate than you might think. Your body will adapt on pretty much every level until you give up, die, or are just unhealthy and miserable. Sufficient calories and fat are almost everyone's friend. Focus on food quality, and most everything else follows. Well, it's more complicated than that too, but that's closer to the truth.

Thank you for not following the trend. I know that some big names started recommending 150-250 g protein. To me that sounds crazy and reckless. Why would anyone do that??? Are any of those "experts" even considering the effect on the environment? I'm not vegan and never could be but eating so much meat must be just as bad as eating 100% vegan and using all that land for crops.

If you're big and active enough it's possible that' a reasonable amount. Sounds like it's more than either you or I need, but I'm a pretty mall person. That said, if the protein is properly sourced it's not necessarily bad for the environment. If you're eating filet from factory farmed cattle then, yes, it's not ideal. But if you're eating nose to tail from regeneratively raised animals and eating sustainably raised fish or even the densest and most sustainable source of protein, insects, it can be a 'good for the planet' way of living. Ever eaten a cricket? Mealworm? I wish there wasn't an 'eww' factor associated with them because they are nutritious, sustainable, and packed with protein. And, they taste pretty decent.

I noticed that you talked about protein in g/lb "body weight" but then also g/lb "lean mass".   Early in the post you refer to 1.4 g/lb body weight, but when you return to analysis of this figure you say "lean mass".   But how can I figure out my lean mass?  I mean, unless I'm "shredded" and have no body fat, it seems a bit of a mystery.   But if I use g/lb directly and start out 100 lb overweight the final recommendation will suggest that I need an additional 75 g - 100 g of protein...until I lose the weight.   So how is your final recommendation of 0.75 g/lb - 1.0 g/lb meant to be applied?  
I saw the interesting suggestion in one source to use height instead of weight to avoid dependence on body fat.  I think the suggestion was one gram per centimeter of height.  I assume this wouldn't adapt to people who have very high (or low?) lean mass.  

First off, nice catch on the Helms 2014 paper. Strictly speaking, it is referring to fat-free lean mass and concludes “ Protein needs for energy-restricted resistance-trained athletes are likely 2.3-3.1g/kg of FFM scaled upwards with severity of caloric restriction and leanness.”
But as for your question, that’s kinda’ the point of the article. There isn’t an easy answer for an individual. If you’re over-fat, you’ll need relatively less protein for you weight, but how much ... nobody can say.
You can get body fat tested via a DXA scan, bioimpedence scale, or even body calipers. Those options are listened in order of decreasing price and accuracy, although for those who are heavier the calipers are reasonable.
I don’t think the height advice makes sense. Going by that rule Melania Trump would require more protein than Sylvester Stallone. Ha! Funny thought.
I’d say focus on protein quality and eat as much as you feel is reasonable. If you’re not highly active, anything between 0.5-1.1 g/lb is probably just fine. Or, if you want to target %Cal from protein, which may work better for you, 18-30% kCal from protein is a decent range.