[Obesity at the cellular level]

Adipocytes are capable of thousand-fold variation size. The considerable size-related variation in lipid accumulation and mobilisation is regulated at different levels of adipocyte metabolism. Immediate metabolic effects are mediated via adrenergic and insulin receptors, which in turn are regulated both by the sympathetic nervous system and by a group of superior steroid hormones exerting their effects via specific receptors. The steroid hormone receptor-hormone complexes interact at a genetic level, modifying the direct hormonal effects of insulin and catecholamines. The density of steroid receptors is probably governed both by genetic factors and auto-regulation. Hypothetically, regional differences in adipocyte metabolic function may depend upon genetic differences in the regulation of hormone receptors, which are subject to endocrine secretion patterns, thus determining the distribution of adipose tissue.