The body is usually in a body with a high basal metabolic rate, divided into physiological and pathological thinness. From the perspective of pathological thinness, the body can become excessively thin in the case of some diseases, such as endocrinological diseases with high basal metabolic rate, such as hyperthyroidism, hyperadrenocorticism, diabetes or chronic long-term infections that consume a lot of body mass, such as tuberculosis, rheumatism, connective tissue disease and anemia are all pathological thinness. In terms of physiological physique, lean physique is usually long-term aerobic exercise or long-term muscle training people, the proportion of developed muscle in the body, muscle content is relatively high, these people resting metabolic rate and basal metabolic rate is high, so that the production of lean physique.