Recent discoveries, notably of the hormones leptin and adiponectin, have revised the notion
that adipocytes are simply a storage depot for body energy. Instead, adipocytes are also
endocrine organs, with multiple metabolic roles in regulating whole-body physiology. Small
adipocytes in lean individuals promote metabolic homeostasis; the enlarged adipocytes of
obese individuals recruit macrophages and promote inflammation and the release of a
range of factors that predispose toward insulin resistance. Exercise activates the AMP …