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According to A. Hutchinson, PhD (Which Comes First, Cardio or Weights? Fitness Myths, Training Truths, and Other Surprising Discoveries from the Science of Exercise, 2011):
- 0.8 grams of protein per kg of body weight is the standard recommendation for non-athletes.
- 1.1 grams per kg is recommended for endurance athletes.
- 1.3 grams per kg is recommended for strength athletes.
1 kg = 2.2 pounds, so:
- A 220 pound strength trainer requires 130 grams of protein per day, whereas a 110 pound strength trainer would need only 65.
- A 220 pound endurance athlete would need 110 grams of protein per day, whereas a 110 pound endurance athlete would need only 55.
- A 220 pound non-athlete would require 80 grams of protein per day, and a 110 pound non-athlete would need to consume only 40 grams of protein per day.
To put this into perspective, the average American (when not dieting) consumes 1.6 grams of protein per kg of body weight each day.
A bit of extra protein is unlikely to do any harm (many of the risks associated with high-protein diets only affect those with particular health issues or vulnerabilities), but it won’t do any good either, and could displace foods that will benefit your health – fruits, vegetables, and complex (healthy) carbohydrates – as well as causing you to gain weight.
Eating too much protein can make you fat
There is a lot of debate about this online, so I went through 25 pages of search results, pulling out only those provided by doctors, university-based medical and research centers, registered dietitians, and peer-reviewed academic journals (excluding “expert” sources that were obviously promoting products or services, and therefore biased). Quotes from reliable sources are provided below, with links if you’d like to go more in-depth with the research:
- Vanderkooi, J.M., Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Your Inner Engine: “Excess dietary carbohydrate and protein are converted into fat for storage.”
- Pesta & Samuel, A high-protein diet for reducing body fat: mechanisms and possible caveats, Nutrition and Metabolism, 2014:“…when energy demand is low, excess protein can be converted to glucose (via gluconeogenesis) or ketone bodies and contribute to a positive energy balance, which is undesirable if weight loss is the goal.”
- University of Utah Genetic Science Learning Center, Building, Burning, and Storing: How Cells Use Food, 2015: “The amount of protein we need to eat to replace what we lose is relatively modest. A generous estimate is 10% of our daily calories, which amounts to 56 grams per day for the average man and 46 grams for the average woman. Any protein we eat beyond what we need for rebuilding is burned for energy, converted to sugar, or most commonly converted to fat . . . regardless of what we eat, weight loss will only occur when we burn more calories than we consume. When a high-protein diet contains more calories than we need, the excess still builds up as fat.”
- Adrienne Youdim, MD, Cedars-Sinai Medical Center, Center for Weight Loss, Carbohydrates, Proteins, and Fats: “If more protein is consumed than is needed, the body breaks the protein down and stores its components as fat.”
- Leslie Beck, Registered Dietitian, Trying to Build Muscle? Don’t Cut the Carbs, 2014: “Consuming more protein won’t enhance muscle building since there’s a limit to the rate at which protein can be synthesized into muscle. The extra protein will be burned for energy or, if your diet is calorie-sufficient, stored as body fat.”
The body is not very efficient at turning protein into fat, so you’d need to eat a very high-calorie, high-protein diet to get fat from excess protein consumption. However, with the Paleo diet trend and myths about megadose protein requirements for muscle building, many people do eat far too much protein.
Another thing athletes should keep in mind is that a diet deficient in carbohydrates, which are its preferred fuel source, will turn to protein to meet its energy requirements, which can result in a loss of lean muscle, particularly for those who also do cardio exercise (and especially for endurance athletes). While cutting down on or even eliminating processed carbohydrates (junk food) is a good idea, very low-carb diets are detrimental to strength and fitness for most people. Not only do they provide insufficient fuel for cardio exercise, but they have been shown to reduce strength training performance as well (Leveritt et al., 1999, Effects of Carbohydrate Restriction on Strength Performance, The Journal of Strength & Conditioning Research, 13[1], 52-57).
Protein content of popular foods
Here are the approximate protein totals for a variety of popular foods (data from Today’s Dietician, 2013, Protein Content of Foods; measurements have been converted from ounces to cups and rounded to the nearest whole gram in some cases to make the list easier to use):
- 3 ounces of chicken (roughly the size of a deck of cards): 28 grams of protein
- 1 cup of cottage cheese: 28 grams of protein
- ½ cup of shredded mozzarella: 28 grams of protein
- 3 ounces of steak: 26 grams of protein
- 3 ounces of turkey: 25 grams of protein
- 3 ounces if lamb: 23 grams of protein
- 3 ounces of salmon or tuna: 22 grams of protein
- 1 cup of pinto beans: 22 grams of protein
- 3 ounces of pork or shrimp: 20 grams of protein
- ¾ cup of Greek yogurt (full fat): 20 grams of protein
- 1 cup of lentils or edamame: 18 grams of protein
- ½ cup of shelled peanuts: 17 grams of protein
- 3 ounces of lobster: 16 grams of protein
- 1 cup of black beans or red kidney beans: 16 grams of protein
- 3 ounces of ham (pig thigh meat) or scallops: 14 grams of protein
- 1 cup of chickpeas, fava beans, or black-eyed peas: 14 grams of protein
- 2 tablespoons of peanut butter: 14 grams of protein
- ½ cup of almonds or pistachios: 14 grams of protein
- ½ cup of walnuts or cashews: 13 grams of protein
- 1 cup of kamut or lima beans: 12 grams of protein
- ¼ cup of pumpkin seeds: 9 grams of protein
- 1 cup of quinoa or green peas: 8 grams of protein
- ¾ cup of regular nonfat yogurt: 8 grams of protein
- 1 cup of skim milk or soy milk: 8 grams of protein
- ¼ cup of sunflower or flax seeds: 7 grams of protein
- 1 egg: 6 grams of protein
- 1 cup of spinach, cooked: 6 grams of protein
For more food articles, see the main Food and Nutrition page. For articles on strength training and other forms of exercise, see the main Fitness page. For articles on health, see the main Mind-Body Health page.