In 10 young, normal-weight subjects, the effects were investigated of carbohydrate overfeeding and prior glycogen-depleting exercise on resting metabolic rate (RMR) and diet-induced thermogenesis (DIT). Subjects were kept on controlled diets in a crossover design for two periods of 8 days, with a 1-week interval in between. During the last 4 days of each period, additional carbohydrates were added to the subjects' diet. The carbohydrate overfeeding started at 15% in excess of the energy requirements on day 1 and increased to 60% on day 4. At the beginning and the end of the carbohydrate overfeeding periods, RMR and DIT were measured, respectively, for 1 and 3.5 hours using a ventilated hood system. In one of the 8-day periods, on evenings before the energy exchange measurements, subjects performed a maximum work capacity test on a cycle ergometer, and then cycled for a total of approximately 80 minutes at fixed percentages of their maximum work capacity. Carbohydrate overfeeding did not affect RMR, but increased DIT significantly, on average by 39%. Glycogen-depleting exercise the day before increased RMR significantly by, on average, 9% and increased DIT (P = .08), on average, by 23%. The impact of exercise on RMR was less when carbohydrate overfeeding was administered, but there was no significant interaction effect of carbohydrate overfeeding and exercise on RMR or DIT. It is concluded that both prior glycogen-depleting exercise and an antecedent diet high in carbohydrates may influence RMR or DIT.