Traditional bodybuilding dogma has always held that more protein is better. While this is true to a point, it can sometimes be more beneficial to decrease your protein intake and get those nutrients from other sources.
Too Much Protein
If you're eating more than 30-35 percent of your daily calories from protein, that's too much. This amount will maximize hypertrophy (muscle building) while leaving room in your diet for optimal levels of other essential nutrients.
30-35 percent of your daily calories is still a lot of protein, and essentially double the RDA, but it falls within the National Academies of Medicine's acceptable macronutrient distribution range, so you don't need to worry about any adverse effects.1
Protein consumed above this level will start to be oxidized for energy rather than being used to create muscle mass.
Think about your diet as a pie chart: x percent of that pie will be made up of protein, y percent fat, and the remainder carbohydrates. Regardless of the percentages you pick, they will always add up to 100 percent. You can never eat above 100 percent, so increasing one nutrient source will always decrease your intake of another.
If you continue to drive your protein intake upward, chowing down on more dry chicken breasts, then the protein percent of your pie will get bigger and bigger. This shrinks the fat and carbohydrate pie slices, thereby reducing your intake of essential fats, fiber, fruits, vegetables, and grains—all of which play important roles in a muscle-building diet. Depending on your fitness goals, there are actually ideal ranges for each macronutrient.
What Happens to Excess Protein
We typically oversimplify protein, thinking it will always go toward growth. It actually does more than drive protein synthesis and provide amino acids for building muscle. Once those needs have been met, your body will actually break down and oxidize protein for energy.2
You don't necessarily want to be a protein oxidizer. You don't want to train your body to break down protein (dietary or muscle) and use it for energy.
Just as switching from a high- to low-carbohydrate diet causes your body to increase the enzymes that burn fat as fuel, eating protein far beyond your body's ability to build muscle with it will cause increases in the enzymes that oxidize protein (both dietary and muscular) for energy.
Maximizing Protein Synthesis
Instead of offering your body excess protein to oxidize for energy, your goal should be to maximize protein synthesis by eating the proper amount of protein at the right times.
We now know that there is both a protein threshold and timing component to protein's muscle-building ability.3 For whatever reason, people have long assumed that you can only digest 30 grams of protein at a time. But your body can certainly digest much more than that in one sitting.
However, 30 grams may be the proper amount of protein needed to get blood amino-acid levels high enough to flip the muscle-building switch.4 Like a light switch, once you flip the protein threshold and initiate protein synthesis, you can't turn it "more" on. Your body will digest protein above that level, but it will be used as fuel, not for additional muscle building.
The other component to protein synthesis is flux. Giving yourself a constant infusion of amino acids throughout the day via protein shakes, eggs, steaks, and chicken isn't actually maximizing protein synthesis. Instead, you need a change in your blood amino-acid levels.5
To reboost protein synthesis, blood amino acids need to drop and then spike. This occurs naturally when you eat 4-5 meals per day, but not if you're drinking a protein shake at every turn. I know it seems counterintuitive, but skip the constant protein-shake sip and you'll actually maximize synthesis.
- Trumbo, P., Schlicker, S., Yates, A. A., & Poos, M. (2002). Dietary reference intakes for energy, carbohydrate, fiber, fat, fatty acids, cholesterol, protein and amino acids. Journal of the American Dietetic Association, 102(11), 1621-1630.
- Witard, O. C., Jackman, S. R., Breen, L., Smith, K., Selby, A., & Tipton, K. D. (2014). Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. The American Journal of Clinical Nutrition, 99(1), 86-95.
- Schoenfeld, B., Aragon, A. and Krieger, J. (2013). The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. Journal of the International Society of Sports Nutrition, 10(1), p.53.
- Symons, B., Sheffield-Moore, M., Wolfe, R. and Paddon-Jones, D. (2009). Moderating the portion size of a protein-rich meal improves anabolic efficiency in young and elderly. Journal of the American Dietetic Association, 109(9), pp.1582-1586.
- Rasmussen, B., Tipton, K., Miller, S., Wolf, S. and Wolfe, R. (2000). An oral essential amino acid-carbohydrate supplement enhances muscle protein anabolism after resistance exercise. Journal of Applied Physiology, 88, pp.386-92.