Abstarct: Aim: The aim of this study was to compare the effects of maximal exercise with and without caffeine supplementation on serum alpha-amylase, blood glucose, insulin, and energy intake in overweight/obese individuals. Materials and methods: This crossover study was conducted on 20 overweight/obese male and female volunteers aged over 18 years with a body mass index (BMI) > 25 kg/m2. Participants were randomly assigned into two conditions: maximal exercise with caffeine supplementation and maximal exercise without caffeine supplementation (placebo). Participants received a dose of 200 mg caffeine capsule and starch powder and then performed 30 minutes of submaximal exercise at 60% of HRR. Blood samples were collected before and after caffeine supplementation and following exercise. The research data was analyzed using paired and independent t-test at a significance level of 5%. Result: According to the study results, caffeine increased blood glucose, insulin, and serum alpha-amylase (p < 0.05). Exercise significantly increased serum alpha-amylase levels and significantly decreased insulin and blood glucose levels (p < 0.05). The decrease in insulin and blood glucose levels and the increase in serum alpha-amylase in response to exercise were greater with caffeine supplementation than with placebo (p < 0.05). Conclusion: It appears that caffeine supplementation enhances insulin and blood glucose responses to exercise. Additionally, an increase in calorie intake was observed after exercise bout in both conditions, independent of caffeine intake.