Effectiveness of high-intensity interval training for weight loss in adults with obesity: a randomised controlled non-inferiority trial

INTRODUCTION: Obesity treatment guidelines suggest moderate-intensity continuous training (MICT), but the patient’s compliance to this indication remains low. High-intensity interval training (HIIT) is a time sparing training mode whose metabolic effects are not clear. This study aimed to determine whether a 12-week HIIT was more effective than MICT for weight loss in obese adults. METHODS: 44 obese subjects were randomised and trained with isoenergetic treadmill exercises for 12 weeks: MICT (60% of maximal oxygen peak, VO(2)peak) or HIIT (3–7 repetition of 3 min 100% of VO(2)peak interspersed by 1.5 min 50% of VO(2)peak). The primary outcome was a change in body weight; the secondary outcomes were changes in body composition, blood pressure, lipid profile, glycaemia, insulin and VO(2)peak. RESULTS: 32 subjects (53% male, mean age: 38.5 years, mean body mass index: 35.5 kg/m(2)) completed the trial. MICT and HIIT showed comparable effect within groups in weight loss (−6.0 kg (−9.0 kg to −3.0 kg) vs −5.7 kg (−8.3 kg to −3.1 kg)), changes in fat mass (−2.9% (−4.4% to −1.4%) vs −3.6% (−5.9% to −1.2%)), fat free mass (−5.3% (−7.8% to −2.8%) vs −5.5% (−8.3% to −2.6%)), diastolic blood pressure (−5.5 mm Hg (−10.6 mm Hg to −0.3 mm Hg) vs −5.8 mm Hg (−11.3 mm Hg to −0.3 mm Hg)) and low-density lipoprotein cholesterol (−16.4 mg/dL (−30.8 mg/dL to −2.0 mg/dL) vs −14.7 mg/dL (−25.6 mg/dL to −3.8 mg/dL)). There was a significant change between groups in VO(2)peak (HIIT: +461.6 mL (329.3‒593.8 mL); MICT: +170.5 mL (86.7–254.4 mL); p<0001) and duration of sessions (HIIT: 35.0 min (31.7 ‒35.6 min); MICT: 46.5 min (40.2‒48.3 min); p<0.001). No significant changes in systolic blood pressure, high-density lipoprotein cholesterol, triglycerides, glycaemia or plasma insulin were observed. CONCLUSIONS: In healthy adults with obesity, HIIT compared with MICT induced similar weight loss and cardiovascular risk factors improvement but resulted in a larger increase in cardiorespiratory fitness over a shorter period.