The ever-evolving answer to this question is getting increasingly clear as scientists now have a better understanding of protein metabolism. There’s no doubt that protein plays a huge role in getting huge, but how much is enough to support maximum muscle protein synthesis (MPS) and more importantly, are there risks involved with over consumption? A registered dietitian may recommend under 60 grams of protein per day, while top-level bodybuilders quadruple that amount. It was once thought that increased protein consumption could lead to kidney damage or cause calcium leaching, making your bones brittle. Fortunately, scientists have conducted an incredible amount of studies to determine the safety of protein consumption with two published review papers focused specifically on analyzing the research. The verdict? No adverse effects on renal function, kidney damage, or calcium leaching when protein levels were 2.0g/kg and 2.8g/kg 1, 2. So which way do you lean? In reality, for most of us, there’s a middle ground that will support your desired muscle growth. Just because high levels of protein have been deemed safe doesn’t mean you should go abandoning your other macronutrients on your quest for new gains. Consuming the optimal amount of protein may leave room in your macros for more energy-producing carbs!
It’s also important to note that BCAAs from metabolized protein food sources are responsible for creating an anabolic environment in your body. This leads to the question, which amino acid is most important in signaling muscle protein synthesis? Leucine! This amino acid is responsible for increased muscle protein synthesis as well as limiting muscle protein breakdown while at rest3. Whey isolate has the highest percentage of leucine per gram and each protein source has a varying amount, i.e., chicken with 1.48g of leucine per 100g and 20g of whey isolate boasting approximately 2g of leucine. The effects of leucine on muscle protein synthesis seem to last for three hours after eating, and it’s recommended to wait four to six hours between high-protein meals in order to re-sensitize your body to be able to peak MPS once again and consume a free form source of leucine (3g), say in the BCAA supplement, one hour post meal to achieve maximal MPS 4.
So let’s wrap it all up. In all healthy athletes, research indicates that protein consumption above the recommended daily allowance is safe and essential in achieving your full potential while training. Eating high-protein meals containing 3g of leucine every four to six hours will maximize MPS. Thus, 15–20g of leucine per day from whole food and supplemental protein or amino acid formulas should be your daily target. Just like training hard in the gym, you’ll have to have some accountability to calculate how much leucine your meals pack, but the reward will be some sweet new gains!
REFERENCES
- Manninen, A. 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), p. 45-51.
- Martin, M. F., Armstrong, L.E., & Rodriguez, N. R. (2005). Dietary protein intake and renal function. Nutrition & Metabolism, Vol 2, p. 25.
- Blomstrand, E. Eliasson, J. Karlsson, H.K. Köhnke, R (2006). Branched-chain amino acids activate key enzymes in protein synthesis after physical exercise. J Nutr, 136, p. 269S–273S
- Norton, L.E. Wilson, GJ. (2009). Optimal protein intake to maximize muscle protein synthesis. Agrofood Ind Hi-Tech, Vol 20, p. 54-57.
