Effects of overfeeding on carbohydrate tolerance, insulin secretion, esterification and lipolysis in healthy subjects.

Abstract

Blood glucose, plasma concentrations of insulin, free fatty acids (FFA) and glycerol were measured in 11 healthy lean young adults, in response to a standard high carbohydrate meal, before and during overfeeding with a high carbohydrate or a high fat diet The plasma insulin was unaffected by overfeeding, whilst the hypercaloric high carbohydrate diet enhanced carbohydrate tolerance and the hypercaloric high fat diet hat the reverse effect. Both types of overfeeding depressed the postabsorptive and absorptive concentrations of plasma FFA. Overfeeding with the high carbohydrate diet had no effect on the plasma glycerol concentrations recorded before and after ingestion of the standard breakfast. Overfeeding with high fat diet also failed to alter the postabsorptive concentration of plasma glycerol but the plasma glycerol levels rose following the standard high carbohydrate meal. These findings indicate that: a) overfeeding with a high carbohydrate diet enhances the utilization of glucose by increasing sensitivity to insulin, whilst overfeeding with a high fat diet has the opposite effect; b) esterification of FFA in adipose tissue is stimulated by overfeeding independently of the composition of the diet; c) basal lipolysis in adipose tissue as judged by the postabsorptive plasma glycerol concentrations is unaffected by overfeeding but the antilipolytic effects of insulin on adipose tissue appear to be impaired following the standard meal, when subjects are overfed with a high fat diet.