Ecto mesomorph is a term that refers to a body type that is a cross between ectomorph and mesomorph bodies. Characterized by broad shoulders, narrow waists, ankles and wrists, ecto mesomorphs vacillate between being extremely muscular or lean. Although they can build muscle relatively easy, they lack the powerful explosive strength of mesomorphs and are prone to gaining fat on the stomach and buttocks.
Although William Herbert Sheldon's theory of body morphology separated people into ectomorphs, endomorphs and mesomorphs, Breaking Muscle points out that a great deal of variation among people's bodies exist and sorts them into mixed categories of which ecto mesomorph is one, and that these terms refer specifically to body proportion not existing body tissue such as fat or muscle.
Ben Greenfield Fitness emphasizes the importance of determining body type in order to develop a personalized weight loss and strength building training regime that will accommodate unique needs. Ecto mesomorphs are more common among men than women.
Sheldon later refined his theory and developed a method of body typing known as "somatotyping" in which he analyzed bone length, height-to-weight ratios, fat percentage and more that continues to be used to determine body type. It is known as the Heath-Carter Anthropometric Somatotype model.