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.
Key words
Overfeeding - Blood glucose - Plasma Insulin - Esterification - Lipolysis
