Genetics and body type when gaining muscle mass.

What types of muscle fibers will prevail in a particular person, as well as the ratio of testosterone to estrogen, and where the body stores body fat, is genetically determined. And these factors are also influenced by body type. Ectomorphs have a thin skeleton with a minimum of fat and muscle, they are the hardest to gain muscle mass. Mesomorphs gain muscle mass faster as they tend to be muscular, but endomorphs will have to work hard to lose fat before they see the desired relief.