The striking similarities in the metabolic associations of female androgen excess and male androgen deficiency.

Androgen excess in women and androgen deficiency in men facilitate abdominal adiposity and related metabolic disorders. Moreover, obesity-associated gonadal dysfunction consists of hyperandrogenism in women but hypogonadism in men. We have reviewed the existing evidence on the interplay between sex steroids, adipose tissue and lean mass distribution, and developed a novel hypothesis to explain these apparent paradoxes. We hypothesize that the most beneficial adipose tissue distribution and function is that of normal women, who have low androgen and high estrogen concentrations. Any imbalance favoring an increase in androgen levels in women, and the very high androgen levels characteristic of healthy men, influence adipose tissue distribution and function. Sex steroids determine a favorable (female) or unfavorable (male) body fat distribution and function. However, sex hormones also provide defensive mechanisms against visceral fat accumulation: androgens increase lean and muscle mass in men, decreasing the amount of visceral fat relative to total body mass and its negative consequences, whereas estrogens determine the metabolically safer deposition of body fat into the subcutaneous gluteal-femoral depot in women. This delicate equilibrium may be altered by the presence of gonadal dysfunction, a sedentary life-style or the normal ageing process leading to sarcopenia, and by the development of obesity leading to abdominal adiposity and metabolic disorders in both sexes. In conclusion, sex hormones and gonadal dysfunction play important roles in the pathogenesis of diabesity and its metabolic associations.