What is the best diet for a professional athlete to go on for lean muscle?

Diet and muscle: The dietary key to muscle development is to make sure you are getting enough quality proteins. An athlete typically need 0.8-1.0 grams of dietary protein per day per kilogram of body weight (0.8 g/kg). The average american gets plenty of protein in their diet but you have to add it up to know for sure. Excessive calories, no matter the source, contribute to fat development and not extra muscle.