How much protein do you need in your diet?

Photo credit: bodybuilding.com

Photo credit: bodybuilding.com

By Ari Snaevarsson, Features Editor

Just to preface this article, the specific audience I am speaking to here would be the somewhat healthy (read: not plagued with all sorts of symptoms of metabolic syndrome), somewhat resistance trained population. Certainly, vastly different advice with regards to protein intake applies to the obese population than does the freakishly lean/athletic population.

Nonetheless, the advice I have detailed below strikes somewhat in the middle, and I have done my best to avoid sweeping claims that would be totally different between these different subpopulations.  I also want to apologize for the excessive length here; after strategically breaking the physiology side of this series into three articles, I might legitimately go crazy if I do the same for what was supposed to only be an afterthought of an article.

1 g/lb of body weight is more than you need

People often refer to the “golden rule” that optimal protein intake resides at the mark of 1 gram per pound of body weight.  In reality, this number would be seen as laughably high to most sports nutrition scientists who have actually spent time considering research.

Menno Henselmans, of Bayesian Bodybuilding – whose rather recent, first-of-its-kind review of the scientific legitimacy of the “metabolic damage” concept I analyzed ad nauseum over on my main site, NoFluffStrength – wrapped all of this up efficiently on his site.  Through analysis of the plethora of studies on optimal protein intake that are available, he concludes that there is no merit for consuming anything above 0.82g protein per pound of body weight.

This was even the case in the context of significant caloric restriction (1000 kcal under maintenance) – 0.82g was more than enough for the subjects to maintain muscle mass.  Therefore, I cannot honestly substantiate claims that anything above this figure will provide any actual physiological advantage.  In fact, this is right around the number I have been using in my own diet for quite a while, and I can say from experience that my previous endeavors utilizing intakes anywhere from 1g/lb to 2 or 3g (back in my glory days of bro-tein shakes and “dreamers’ bulks”) conferred no additional benefits, at least none that were apparent to me.

Exception: satiety

The only reason I could see for exceeding this amount by much would be for the purposes of increased satiety.  You will recall in the last article that protein’s satiating properties probably stem from its notable impact on diet-induced thermogenesis (DIT).

That said, understand that protein is still a source of calories, and we have already debunked the idea that its impact on metabolic rate renders it an “exception.”  So, if you are looking to add protein into your diet for the purpose of satiety, it will necessarily have to replace some other macronutrient, to keep the diet isocaloric.

But what about staving off muscle catabolism during weight loss?

In theory, if there was a period in which you would want to shoot for the greater end of the spectrum for appropriate protein intake, it would be during a fat loss phase.  Our goal is to maintain, or possibly increase, muscle mass during this phase, which necessitates an adequate protein intake.  Especially near the end of a dieting bout, it is important to offset the chance of protein catabolism, in which the body resorts to degrading body proteins for their amino acids to be used as an energy source (and when we pull from the amino acid pool, we necessarily draw from what otherwise could have served to promote muscle protein synthesis).

However, as is the case with most sports nutrition phenomena, the likelihood of this occurring to any discernible degree is low.  Unless you have been sustaining significant caloric restriction for the better portion of a year (i.e. bodybuilders/physique competitors), the literature simply does not support any legitimate fears of your body resorting to this.  As explained in great detail in the Institute of Medicine’s “The Role of Protein and Amino Acids in Sustaining and Enhancing Performance,” the energy cost of breaking down body proteins and deaminating amino acids for substrate is large enough that you would have to be in a serious state of metabolic distress for your body to rationalize such an effort.

That said, it is worth noting that within the context of poorly constructed dietary interventions (generally those based off of sensationalist premises – think going zero-carb, doing a “juice cleanse,” inappropriate fasting protocols, etc.), this might be a factor.  Then again, the take-home message there is not to ramp up protein intake but to diet smarter.  At the end of the day, as was mentioned earlier, even when significantly energy-restricted, dieters will likely not gain any advantage by adding much more protein in their diet than the 0.82g/lb figure.

Per pound of body weight or lean body mass?

This brings us to an interesting question to which actual physiological explanations are limited.  Many sources speak of protein needs in terms of grams per pound of bodyweight, while others contest that to get a more accurate measurement of optimal protein intake, we must rely on pounds of lean body mass (LBM).  The reasoning goes, this is the tissue we are aiming to build/retain with dietary protein, so it makes the most sense to use this as our metric.

Henselmans himself admitted ignorance to this dilemma, which speaks to the lack of attention to detail that sports nutrition scientists tend to pay (because cool, flashy results tend to trump perfect study designs and inquisitiveness, unfortunately).

However, I believe that most of us do not have accurate measures of our body fat percentages, and therefore proportion of body weight contributed by LBM.  For that reason, unless one is a competitive physique athlete, there is little actual reason to concern ourselves with these nuances.  Furthermore, just as body mass index (BMI) is by itself a highly inaccurate measure of clinically troubling body composition (relying on a 2-compartment model of body fat, completely ignoring visceral vs. subcutaneous fat discrepancies, etc.) and yet a beautiful means of extracting epidemiological trends, we must concede that fixating on LBM, and not simply body weight, for protein intake guidelines is a losing battle that would cost us the wealth of data we now have available.

Suffice it to say, obese individuals can probably afford to expand their margin of error down to 0.6g/lb, while extraordinarily lean individuals (of whom I doubt few are reading this article – so do not be so quick to cast yourself into this group) might want to bump their intake up to 0.9 or 1g/lb.

NOTE: It may seem odd to go back and forth between the Metric and Imperial system like this, but note that it is only for simplicity’s sake – the universal measurement of macronutrients has been decided to be in grams, and for most Americans, bodyweight is best conceptualized in pounds.

Stay tuned next week for a special edition in which I reveal some information you will undoubtedly find highly useful in your dieting efforts.  Have a great week!

 

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