Hmm ~ Synthesize the answers of the above people. Many stars, especially female stars, will go on a diet to lose weight, so many people may get anorexia. Many people are vegetarians. There is also regular exercise. Stars usually hire fitness coaches and the like to help them exercise more healthily. Then there is occupational stress. Many stars are under great pressure and may become "heavy smokers", or drink and take drugs. There are also many possibilities that some people just don't like to grow meat.