Caffeine ingestion increases the insulin response to an oral-glucose-tolerance test in obese men before and after weight loss.

Background: Caffeine ingestion decreases the insulin sensitivity index (ISI) for an oral-glucose-tolerance test (OGTT) and decreases insulin-induced glucose disposal in lean male subjects during a hyperinsulinemic clamp.

Objective: We examined the effects of caffeine ingestion on insulin and glucose homeostasis in obese men before and after a nutrition and exercise intervention.

Design: Nine sedentary, obese [body mass index (in kg/m(2)): 34.