Protein for Bodybuilding: How Much Is Too Much?

Don't Get Extreme With Bodybuilding Protein

Body Builder
Steve Williams Photo/Photodisc/Getty Images

It's true that bodybuilders and weightlifters need to keep the protein up in their diet in order to maintain and build the large muscle mass which is so important to their sports or recreation. Protein is found in meat, fish, chicken, beans, milk, soy products like tofu, and in lesser amounts in nuts and grains.

Daily Requirements

The estimated daily requirements are set by various nutrition authorities in each country.

In the U.S., the Department of Agriculture (USDA) sets the guidelines for nutrients like protein as well as other major vitamins and minerals. For most people of average weight, the protein intake is set at less than 70 grams each day.

Athletes may require quite a bit more than this to support the repair and growth of muscle and to protect against the general hardships of vigorous training and competing. Yet sports nutrition authorities generally recommend no more than about twice the daily recommended allowance applicable to less active people.

Excess Protein Is Not Required

Some bodybuilders and weight training athletes have taken this recommendation for extra protein to extraordinary limits and well beyond any scientific recommendation. While excessive protein seems to do no harm in healthy, active people up to a point, the risk may be more substantial for someone with kidney disease, are overweight, or have diabetes.

Excess protein beyond the requirements of the body is broken down by amino acids into ketones, glucose, or energy cycle intermediates for energy. Some protein is converted to ammonia and then urea and excreted.

Getting excess protein is encouraged by the extraordinary vigor of the powdered protein supplement industry in the weight training and bodybuilding markets.

Skim milk powder can supply all the extra protein required and at a fraction of the price of some expensive supplement brands.

Go through an example to demonstrate the dynamics of protein requirements for weight training.

Three Ways of Determining Protein Requirements

It's possible to suggest a protein intake based on three ways to calculate possible requirements.

  • Quantity per pound or kilogram of body weight per day.
  • Macronutrient percentages, for example a diet of 25 percent protein.
  • The absolute amount of protein per day, 160 grams for example.

Here is how each of these may be determined.

  • Protein by body weight: While the protein requirements for adult males are less than one gram per kilogram of body weight per day, estimates for athletes based on studies that evaluate nitrogen balance, a product of protein breakdown, suggest that up to 2.5 grams/kilogram/day may be required in exceptional circumstances. However, 2.0 grams/kilogram is used by many sports nutritionists as an upper ceiling of protein intake for athletes, weight trainers in particular. (Divide by 2.2 to get protein in grams/pound body weight/day.) Much less than this is going to be sufficient for moderate or less intense exercise.
  • Protein by macronutrient percentage: The macronutrients are a carbohydrate, fat, and protein—essential elements in human nutrition. Government Dietary Reference Intakes (DRI) nominate an upper level of protein intake at 35 percent of total energy. For example, a 100-kilogram bodybuilder eating about 2 grams/protein/kilogram/day would eat 200 grams of protein each day. Even on a diet of 4000 calories per day—not unusual for heavy training—this diet is only 20 percent protein. Two hundred grams of protein is equivalent to about 600 grams of chicken or six grilled chicken breasts. Please note the 200 grams refers to pure protein and not the weight of whole food. So in this sense, moderately higher protein intakes do not exceed government healthy eating guidelines.
  • Protein by daily intake: Considering that the U.S. Dietary Reference Intake for an adult male of 100 kilograms is 80 grams/day (0.8 x 100), you can see that 2 grams/kilogram/body weight/day for 200 grams total is substantially higher. Women require slightly less than this, yet they will need slightly more during pregnancy. Even though the standard dietary reference intakes are calculated to meet the requirements of 98 percent of the population in a particular group, athletes need more per kilo of body weight than sedentary people.

Extreme Protein Recommendations for Bodybuilding

A few bodybuilding and weight training coaches recommend protein intakes of 40 percent of energy. An example is a diet of 40 percent protein, 40 percent carbohydrate, and 20 percent fat. In the 4000 calorie diet of a 100-kilogram bodybuilder, 40 percent protein would be 1600 calories, equivalent to 400 grams of protein at 4 calories per gram. That's 4 grams/protein/kilogram body weight/day; over four times the RDI and twice what's scientifically defensible. Not good.

Fast and Slow Proteins

How quickly amino acids get transported to blood and how quickly they then get assimilated into muscle and other tissue for repair and rebuilding is the basis of this idea. According to some enthusiasts, fast proteins such as whey are superior to slow proteins like casein. Both are derivatives of milk products. Examples are:

  • Egg protein: 1.3 grams/hour
  • Casein isolate: 6.1 grams/hour
  • Whey isolate: 8 to 10 grams/hour

There's not much evidence that these variations make a difference to muscle building over the longer term, although whey has shown some advantage in short-term studies.

Yet the other useful information that can be gleaned from the numbers above is that with an average protein absorption of, say, 7 grams/hour, a theoretical absorption is limited to around 168 grams each day. If accurate, it makes the 400 gram/day protein diets look entirely unnecessary at best.

Safety of High-Protein Diets

Very high-protein diets may not be safe over time for the following reasons:

  • High levels of nitrogen and amino acids can be toxic.
  • High-protein diets are not safe for those people with chronic kidney disease. Up to 20 percent of the population may be undiagnosed.

A Word From Verywell

What you might hear from others at the gym may not produce the results you want and may not be in the best interests of your health. One review found that bodybuilders were following a wide variety of intake levels with no consideration of quality or distribution throughout the day. It is wise not to use extreme amounts of protein supplements. Get a checkup to ensure your kidney function and other aspects of your health are good.

Sources:

Helms ER, Aragon AA, Fitschen PJ. Evidence-based recommendations for natural bodybuilding contest preparation: nutrition and supplementation. Journal of the International Society of Sports Nutrition. 2014;11(1):20. doi:10.1186/1550-2783-11-20.

Helms ER, Zinn C, Rowlands DS, Brown SR. A Systematic Review of Dietary Protein during Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes. International Journal of Sport Nutrition and Exercise Metabolism. 2014;24(2):127-138. doi:10.1123/ijsnem.2013-0054.

Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. 2017;14(1). doi:10.1186/s12970-017-0177-8.

Spendlove J, Mitchell L, Gifford J, et al. Dietary Intake of Competitive Bodybuilders. Sports Medicine. 2015;45(7):1041-1063. doi:10.1007/s40279-015-0329-4.