How fast can you build a muscle, and how fast can you lose muscle?
Individuals vary in the rate at which they gain and lose muscle. Genetics, gender, age, physical condition, training program, and diet all have an effect. Under the best circumstances, the average male can build about 1.5 to 5 pounds of muscle per month and a woman will gain less. The rate of muscle breakdown also varies depending on diet, activity level, fitness level, and whether an acute illness is involved. In a state of complete inactivity, a significant amount of muscle is lost in the first three days, but it slows down after that. Read about how to maximize muscle building from the Guide to Weight Training at About.com.