| Caffeine ingestion has previously been found to decrease insulin sensitivity in lean male subjects at rest. This study examined the effects of ingestion of caffeine (5 mg/kg) on the insulin response to an OGTT in sedentary, obese, male subjects (n = 9) before and after a 12-week caffeine withdrawal, nutrition and exercise intervention. Subjects lost 8.5 ± 1.5 kg and 2.8 ± 0.7% body fat. Caffeine ingestion led to a significantly greater insulin response and decreased estimated insulin sensitivity both before and after the program (p < 0.05), but did not influence glucose or C-peptide responses (p > 0.05). While the lifestyle intervention did not ameliorate the caffeine-induced deterioration in insulin action, it did improve fasted glucose, C-peptide, and insulin concentrations (p < 0.05) and estimated insulin sensitivity (p < 0.05). A 12-week nutrition and exercise weight-loss program with accompanying caffeine withdrawal alleviates insulin resistance, while acute caffeine ingestion prior to an oral glucose challenge induces insulin resistance. |
