Somatopause and adiposity.

Mobilization of lipids is the pivotal action of growth hormone (GH) in both children and adults. The temporal association between declining GH levels and accumulation of body fat with ageing is, therefore, interesting although the cause-effect relationship remains unknown. Recent cross-sectional data suggest that both stimulated and spontaneous GH release is predominantly predicted by the amount of abdominal fat in both men and women. The same study also shows that ageing is associated with an increased metabolic clearance rate and apparent distribution volume, both of which correlate positively with fat mass and negatively with age. Furthermore, the acute lipolytic response to a GH bolus is somewhat lower in older adults (and in women). It is, therefore, proposed that changes in life style and dietary habits, perhaps together with an age-determined reduced lipolytic responsiveness to GH, initiates fat accumulation. The increased fat mass, in turn, inhibits the release and promotes the clearance of GH thus establishing a vicious circle.