Dietary protein intake in excess of the current RDA may be required for optimal muscle growth, especially for individuals involved in heavy resistance-training exercises, who have been observed to require 1.7–1.8 g protein/kg body weight/d. However, benefits of high protein intake have been observed to plateau at intake levels well below those typically consumed by athletes. Intakes greater than 2 g/kg body weight/d have not been shown to be beneficial to strength athletes and their performance benefits are unproven at the present time, contrary to popular myth among bodybuilding society .
Such high intakes can also result in diuresis and dehydration. Furthermore, consumption of dietary protein in excess of the physiological needs can result in compromising the carbohydrate status of athletes and can adversely affect their performance during training and competition. It should be recognized that inadequate energy intake is often the limiting factor for athletes attempting to increase muscle mass. Although endurance athletes do not develop muscle mass to the same extent as strength athletes, bodybuilders, studies have shown that dietary protein intake greater than the RDA may be required to meet the amino acid needs that arise due to the increased oxidation associated with the intensity and duration of endurance sports.
Endurance trained individuals may need to consume 1.2–1.4 g protein/kg body weight/d to meet their needs. The typical American diet provides this amount of protein as long as a mixed diet providing adequate energy is consumed. Individual athletes who restrict energy intake or high-quality protein intake, such as vegetarians, may be at risk of consuming insufficient protein.