The effects of time-restricted eating and unsupervised interval training on fat mass, body weight and VO2peak in adults with overweight or obesity. Preliminary findings from a randomized controlled trial

Abstract

Background Obesity is a current epidemic and is associated with cardiovascular and metabolic diseases, as well as premature death. Even if physical activity (PA) and a healthy diet are first-line options for prevention and treatment of obesity, many adults fail to adhere to current guidelines for PA and dietary intake. Time-restricted eating (TRE) and high intensity interval training (HIIT) are two diet-exercise strategies that can improve cardiometabolic health in adults with overweight or obesity.

Objective The aim of this study was to determine the combined effect of 7 weeks of TRE and unsupervised HIIT on body composition and cardiorespiratory health among adults with overweight or obesity.

Methods This study was a randomized controlled trial (RCT) with two parallel groups. Men and women 18-50 years old were randomly allocated 1:1 to an intervention group (TREHIIT) or a no-intervention control group (CON). Participants in TREHIIT were asked to reduce daily time-window of energy intake to ≤ 10 h/day and to undertake three unsupervised HIIT sessions for 7 weeks. The primary outcome was change in fat mass and secondary outcomes were changes in body weight and peak oxygen uptake (VO2peak), in TREHIIT compared with CON.

Results There were 20 participants that were included in the analysis (TREHIIT = 11, CON = 9). There was no statistically significant difference in fat mass (-1.2 kg (95% confidence interval (CI) -3.35, 0.98, p = 0.266), or body weight (-1.6 kg (95% CI -3.79, .671, p = 0.159) between the two groups. There was a statistically significant difference in VO2peak and VO2peak increased after TREHIIT compared with CON (+ 3.3 ml/min/kg (95% CI 2.28, 6.35, p = 0.034)

Conclusion The combination of TRE and unsupervised HIIT for 7 weeks did not reduce fat mass or body weight in adults with overweight/obesity. The intervention induced a clinically significant increase in VO2peak, which helps to increase insulin sensitivity, and reduce the risks of cardiovascular disease, cardiovascular mortality and all-cause mortality.