Effect of Aerobic Exercise Intensity on Energy Expenditure and Weight Loss in Severe Obesity—A Randomized Controlled Trial

OBJECTIVE: This study aimed to compare the effects of two aerobic exercise programs of different intensities on energy expenditure. METHODS: This was a single‐center randomized controlled trial of patients with severe obesity allocated to a 24‐week moderate‐intensity continuous training (MICT) program or a combined MICT with high‐intensity interval training (HIIT/MICT) program. The primary outcome was energy expenditure during exercise (EEDE). Secondary outcomes included resting metabolic rate, cardiorespiratory fitness, and body composition. RESULTS: A total of 82 (56% females) patients were screened, and 71 (55% females) patients were allocated to HIIT/MICT (n = 37) or MICT (n = 34). Per‐protocol analysis showed that EEDE increased by 10% (95% CI: 3%‐17%) in the HIIT/MICT group (n = 16) and 7.5% (95% CI: 4%‐10%) in the MICT group (n = 24), with no differences between groups. In the 8‐ to 16‐ week per‐protocol analysis, the HIIT/MICT group had a significantly larger increase in EEDE compared with the MICT group. Resting metabolic rate remained unchanged in both groups. HIIT/MICT and MICT were associated with significant weight loss of 5 kg and 2 kg, respectively. CONCLUSIONS: Patients completing a 24‐week combined HIIT/MICT program did not achieve a higher EEDE compared with those who completed a 24‐week MICT program. The HIIT/MICT group experienced, on average, a 3‐kg‐larger weight loss than the MICT group.