Effects of a very-low-calorie diet on adrenergic responsiveness in human adipose tissue.

Nineteen obese women were given a strictly-defined very-low-calorie diet for three weeks, and changes in adipose tissue lipolysis were studied using adrenergic drugs. The beta-receptor responsiveness was tested by isoprenaline. Before the diet, we found a negative relationship between basal value and isoprenaline-net effect on glycerol release; after the diet, its relationship disappeared, but the beta-stimulated level remained at a similar maximum. The alpha-receptor responsiveness was studied using clonidine, which significantly inhibits lipolysis; this effect was twice as high after the diet than before. Adrenaline-induced lipolysis was also studied; we found a dose-dependent response, and after a diet a negative linear relationship between basal and adrenaline net-lipolysis, so that adrenaline became antilipolytic for the high values of spontaneous lipolysis. We conclude that: (1) diet does not modify adipocyte-beta-receptor responsiveness, but it increases alpha-receptor responsiveness; (2) relationships between basal lipolysis and the lipolytic responsiveness of adrenergic receptors, which already exist with the spontaneous feeding, are enhanced by the hypocaloric diet, but in such a way that adipocyte-lipolysis remains within a given range; (3) we were unable to find any relationship between rate of weight loss and amplitude of adrenergic-receptor responsiveness.