Protein and weight loss
In a study, 13 obese men were split into two groups and fed low-calorie diets. One group received a high-protein diet (45% protein, 25% carbohydrate and 30% fat) and the other a high-carbohydrate diet (12% protein, 58% carbs and 30% fat). Not only was weight loss greater in the high-protein group but basal metabolism decreased less than in the high-carb group, suggesting that the high-protein diet was able to offset the loss in lean body mass (basal metabolism being a function of lean body mass) that normally occurs while dieting.
No studies of this type have been carried out on athletes, but it seems likely that high-protein diets have something to offer athletes seeking a reduction in body fat while conserving muscle tissue. While high-protein/low-carbohydrate diets of the type described above would not contain sufficient carbohydrate to permit normal training, our mythical 70kg athlete, consuming a 25% protein diet on a mildly calorie-restricted diet of 2,500kcals per day, would be consuming around 600kcal of protein, or 150g, a day. This is well within the ‘safety zon
e’ of 2-3 times the RDA (0.8-1.0g per kg per day) yet with a sufficiently high protein content to exert an increased satiation effect.
Moreover, the athlete would still be able to consume up to 50% carbohydrates (1,250kcal per day, sufficient for moderate training volumes), while consuming enough calories (25%) from fat to meet essential fat requirements. However, athletes need to remember, given the importance of carbohydrate for energy requirements, that even this regime would contain insufficient carbohydrate for higher-volume training and competition phases! In summary, there is good evidence that athletes need a plentiful supply of protein in their diets and that, contrary to previous recommendations, they do need substantially more protein than their sedentary counterparts – at least 50% and possibly up to 120% more. For a 70kg athlete, this can mean up to 150g of pure protein per day.
However, the role of carbohydrates in supplying energy for fuel and recovery remain as important as ever, which means the diet must contain high-quality, low-fat sources of protein in order to enable adequate carbohydrate intake without an overall excess of calories. Simply assuming that because you eat more food than the average person you’ll be consuming adequate protein is not good enough!
There is no evidence that routinely exceeding the recommended protein intake has any additional benefits for nitrogen balance, unless this extra protein is consumed as a protein/ carbohydrate drink before, during or after training – something we’ll tackle in the next article starting on page 21. However, there is evidence that even higher protein intakes may help suppress appetite, control hunger and reduce lean tissue loss during restricted calorie routines, which may be useful for athletes needing to reduce or maintain body weight, although such diets are not really compatible with high-volume training routines.
Finally, despite what you may have read elsewhere, healthy athletes can rest assured that high-protein diets containing up to three times the current RDA for protein are perfectly safe, although it is important to remain well hydrated on such diets.