What Is Truly Needed For Maximum Muscle Gain In Actual Protein Intake?

Well, the answer is never cut and dry is it? Let’s talk about what we know, it is clear that the optimal protein intake is higher than some recommendations; in one study it was shown that a protein intake of 2.1g/kg provided superior muscle mass gains to a protein intake of 1.2g/kg in weightlifters (Tipton et al, 2004).

It is also known that even in a very slight caloric deficit (~100kcals) while performing high levels of activity, the upper levels of the recommended protein intake for athletes (2.0g/kg) are not always sufficient to maintain nitrogen balance (Manninen 2004).

We also know that the current upper level recommendations are precarious with regards to muscle maintenance while on a diet, even if the caloric deficit is very mild. Lastly, it has been shown that intakes as high as 3.0g/kg (or 40% of calories) have no significant health risks (Tipton et al, 2004). So, not only are the current recommendations suboptimal for weight lifters, and not enough to maintain muscle mass while doing high level s of activity on a diet, but higher intakes seem to have no risks.

Another important point made in some more recent studies, is that Muscle Protein Synthesis (MPS) is increased in a dose-dependent fashion in response to protein. Therefore, it may be more useful to suggest a per meal protein intake in addition to a daily total. Since maximal muscle growth occurs due to an increase in MPS, it may be optimal to focus not only on total protein intake, but also frequency and amount of protein at each meal. In fact, in the most recent research it has been shown that MPS is maximally stimulated by 3-4g of the branch chain amino acid Leucine (or .05g/kg of Leucine), and that it can only be maximally stimulated every four to six hours. This research is the first of its kind in that it examines not only nitrogen balance, but the MPS gene-signaling effects of amino acids. Depending on protein source, it typically takes anywhere from 30-50g of protein to meet the 3-4g Leucine requirement. Based on the frequency MPS can be stimulated, this suggests an optimal protein intake for muscle growth close to 2.5-3.0g/kg (Norton et al, 2009).

So, It would appear that higher than normally recommended protein intakes might be prudent for athletes looking to gain muscle mass or maintain it while dieting. For those that are metric-system challenged, 2.5-3.0g/kg would be right around 1.1-1.4g/lb, so a 200lbs male bodybuilder would benefit from eating 220-280g of protein daily, evenly divided into meals every 4-6 hours, more if dieting, less if eating at maintenance or in a gaining phase.

Ah, you say there are risks for kidneys etc – really?

But do high dietary protein intakes carry health risks? In a review of 41 studies examining the purported adverse affects of high protein diets in athletes, it was noted that protein intakes of 2.8g/kg did not impair kidney function in the short term (Manninen 2004). In an even more comprehensive review of 111 studies, specifically looking at protein intake and kidney function, it was found that athletes who habitually consumed over 2.0g/kg of protein showed no impairments in renal function (Martin et al, 2005).

In direct studies on non-athlete populations, similar results were found. This implies that neither the physical activity of athletes nor a possible bias held by the review authors is skewing the data. One study showed that there were no detrimental effects on kidney, liver or bone health after one year of consuming protein intakes of 2.2g/kg of lean body mass (Li et al, 2010). Another study showed that a diet consisting of 25% protein with an additional 50g of supplemental protein daily, had no ill effects on health (it also happened to be the best for maintaining a healthy weight after dieting) (Claessens et al, 2009).

So there you go, some science with info to back it up 😉

References
Bradley-Popovicha, G. E., & Mohr, C. R. (2003). Augmented protein intake for athletes: Are safety concerns well founded? Journal of Chiropractic Medicine, 2(1): 13–15.
Claessens, M., van Baak, M., Monsheimer, S., & Saris, W. (2009). The effect of a low-fat, high-protein or high-carbohydrate ad libitum diet on weight loss maintenance and metabolic risk factors. International Journal Of Obesity (2005), 33(3), 296-304.
Li, Z., Treyzon, L., Chen, S., Yan, E., Thames, G., & Carpenter, C. L. (2010). Protein-enriched meal replacements do not adversely affect liver, kidney or bone density: an outpatient randomized controlled trial. Nutrition Journal, 9: 72.
Manninen, M. H. (2004). High -Protein Weight Loss Diets and Purported Adverse Effects: Where is the Evidence? Journal of the International Society of Sports Nutrition, 1(1): 45-51.
Martin, M. F., Armstrong, L.E., & Rodriguez, R. R. (2005). Dietary protein intake and renal function. Nutrition & Metabolism (London), 2: 25.
Norton, L., E., & Wilson, G. J. (2009). Optimal protein intake to maximize muscle protein synthesis: Examinations of optimal meal protein intake and frequency for athletes. Agro Food Industry High-Tech, 20(2): 54-57.
Phillips, S. M., Moore, D. R., & Tang, J. E. (2007). A Critical Examination of Dietary Protein Requirements, Benefits, and Excesses in Athletes. International Journal of Sport Nutrition & Exercise Metabolism, 17S58-S76.
Tipton, K. D., & Wolfe, R. R. (2004). Protein and amino acids for athletes. Journal of Sports Sciences, 22(1), 65-79.