Anyone who pursues bodybuilding or other strength sports quickly learns that the U.S. government guidelines skimp on protein. While there's near-unanimity that Uncle Sam undervalues the muscle-building macronutrient, debates rage about what the proper amount actually is. There are also rumblings, verging on fear-mongering, that too much protein can wreck your kidneys and do all sorts of other harm to your body.
Spoiler alert! It doesn't. Let's look at some of the common myths—as well as some facts—about high-protein diets.
Myth 1: High-Protein Diets Cause Fat Gain
Not true. The recommended daily allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day. Several years ago, in my capacity as a researcher at Nova Southeastern University in Fort Lauderdale, Florida, I performed a study in which my team had subjects consume 4.4 grams of protein per kilogram of body weight per day, more than 5x the RDA.
These subjects didn't gain fat mass. Nor did they gain lean-body mass. However, when we increased the amount of training the subjects performed, we saw a drop in fat mass and an increase in lean-body mass.
Put simply, it's very difficult to get fat if the only thing you overfeed on is protein.
Myth 2: High-Protein Diets Wreak Havoc on Your Kidneys
Here at the university, we have data showing that if you are a trained male bodybuilder and consume a high-protein diet for at least two years, you will experience no harmful effects to your kidneys, liver, or blood lipids.
Myth 3: High-Protein Diets Leach the Calcium From Women's Bones
According to this myth, eating too much protein can make a woman's bones brittle and weak. We have done studies up to six months in length that looked at the effect on the bones of women who consumed 2.5-3.0 grams of protein per kilogram of body weight per day—about three times the RDA. Once again, we found no decrease in bone health. In fact, the data suggested that if women eat a high-protein diet, their lumbar bone-mineral density, at least, may actually increase!
The Truth
To experience the most benefit from their workouts, bodybuilders and other athletes should consume at least 1 gram of protein per pound of body weight, or 2.2 grams of protein per kilogram of body weight. Not only will this extra protein help you build more lean muscle mass, but it will also diminish your appetite, making you less apt to cave in to cravings.
Protein can help you lose weight because of its ability to act as a potent thermogenic agent. That means your body burns more calories digesting protein than it takes to digest an identical amount of carbohydrate and fat. Protein can also burn fat by increasing the number of calories you use during "non-exercise activity thermogenesis," aka NEAT. NEAT refers to the energy you use to do everything except sleeping, eating, and sports-like exercise. NEAT activities include walking to and from work, typing, doing yard work, climbing stairs, even fidgeting where you sit.