Energy Deficit Required for Exercise-induced Improvements in Glycemia the Next Day.

PURPOSE: This study determined the impact of an exercise-induced energy deficit on postprandial and 24 h glycemic control the day after a session of exercise.

METHODS: Fifteen healthy participants (m/f = 5/10, 27 ± 6 yr, body mass index = 24 ± 3 kg·m, peak oxygen consumption [V˙O2peak] = 36 ± 9 mL·kg·min) completed two separate 5-d experimental trials performed under "free-living" conditions. On day 1 of each trial, participants were fitted with a continuous glucose monitor and abstained from exercise. Day 2 served as a nonexercise control (NoEx). On day 3, participants exercised at 3:00 PM (65% V˙O2peak) until they expended 350 kcals (~45 min). The diet during both experimental trials was identical with the exception of meals after this exercise session. During one trial, the dinner after exercise did not replenish the 350 kcal expended during exercise, thereby establishing an exercise energy deficit (ExDEF). During the other experimental trial, the dinner after exercise contained an additional 350 kcal to compensate for the energy expended during exercise, and thereby maintained energy balance after exercise (ExBAL). Free-living glycemia was measured the day before exercise (NoEx) and the day after exercise under ExDEF and ExBAL conditions.

RESULTS: The day after exercise, 3 h postprandial area under the curve was lower after breakfast in ExDEF compared with ExBAL (16.0 ± 1.8 vs 17.0 ± 1.6 mmol·L·h per 3 h, P = 0.01), but did not differ between groups after lunch (P = 0.24), dinner (P = 0.39), or evening snack (P = 0.45). Despite differences in the glycemic response to breakfast, 24 h glycemia did not differ between ExDEF and ExBAL (area under the curve = 128 ± 10 vs 131 ± 10 mmol·L·h per 24 h, respectively; P = 0.54).

CONCLUSIONS: An exercise-induced energy deficit lowered the glycemic response to breakfast the next day-but this energy deficit did not impact total 24 h glycemia, the day after exercise in metabolically healthy adults.