Eating a high-protein diet is the best way to lose fat while maintaining strength and power. A groundbreaking study in the Journal of the International Society of Sports Nutrition found that putting elite male gymnasts on a high-protein, very low-carb diet did not compromise athletic performance or muscle mass but it did produce significant fat loss.
The study used gymnasts from the Italian national team and had them eat a very low-carb diet for one month in which they ate 55 percent fat, 40 percent protein and 5 percent carbs (carbs totaled no more than 28 grams, strictly from green vegetable sources). The study included a “control” portion that was conducted three months after the low-carb diet in which the gymnasts ate their regular diet for a month (composed of 46 percent carb, 39 percent fat, and 15 percent protein) and then performed the same body composition and strength tests.
The high-protein, low-carb diet was primarily meat, green vegetables, eggs, cheese, and olive oil. The gymnasts were allowed to eat as much as they wanted of those foods. They avoided alcohol, bread, pasta, rice, milk, yogurt, and barley coffee but were allowed regular coffee. They were given herbal, vitamin, and electrolyte supplements to support the diet. The gymnasts performed regular gymnastics and strength training during the study.
Results showed that the gymnasts lost an average of 2 kg of fat, dropped 2.6 percent body fat, while maintaining lean mass. Overall, they lost 1.6 kg of body weight, which is very significant since gymnasts want to be as light as possible. When they returned to the regular diet that was higher in carbs, they gained back 1.5 kg of fat, ending with 7.7 percent body fat.
Just as important, the gymnasts did a series of strength and power tests and performed equally well before and after both the low-carb and normal carb diets.
The most interesting part of the study is the analysis of why it was so effective and safe. This was a ketogenic diet, meaning that the lack of carbs requires the body to produce ketones. The ketones are a fat-based source of fuel that the body uses for metabolic needs, while sparing muscle protein. A catabolic state is avoided, and instead of pulling amino acids from the muscle to use for fuel, the body pulls fat and uses the ketones.
Insulin stays very low on such diets, meaning that it is hard to put on muscle mass because insulin triggers protein synthesis pathways in the body. Therefore, the maintenance of muscle mass in this study is very significant and it calls our attention to a “threshold” dose of protein necessary to avoid the muscle loss on a very low-carb diet. Previous studies have found that a threshold dose of 1.7 g/kg/bw a day is necessary, but this study used about 2.8 g/kg/bw a day. The higher dose is likely ideal due to the very intense training of the gymnasts.
A few things should be noted in considering such a diet:
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Ancestral humans ate about 30 percent protein daily, which corresponds to about 3g/kg/bw a day, indicating that a very low-carb, high-protein diet can be safe if done properly.
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It took a week for the athletes to feel “normal” on the diet. Over the first seven days they did not feel as strong or as powerful and had difficulty completing some training exercises. After a week they recovered previous strength, power and stamina and had no problems with the diet.
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Researchers write that it takes seven days for full metabolic adjustment to a low-carb ketogenic diet. Just because you don’t feel “right” during the first week doesn’t mean it won’t be effective.
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It’s recommended to take an electrolyte supplement containing sodium and potassium to maintain an effective nitrogen balance and preserve lean tissue.
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Supplemental fiber and protein can be used to drive protein intake up. Added fiber is necessary because a low-carb diet will be extremely low in fiber.