Early time-restricted eating with energy restriction has a better effect on body fat mass, diastolic blood pressure, metabolic age and fasting glucose compared to late time-restricted eating with energy restriction and/or energy restriction alone: A 3-month randomized clinical trial

BACKGROUND & AIMS: Time-restricted eating (TRE) has attracted increasing attention from researchers and the public. Recent studies suggest that the combination of TRE with energy restriction (ER) may have more favourable effects on both physical and biochemical aspects compared to ER alone. The aim of the present 3-month intervention study was to determine the effects of an 8-h early time-restricted eating and an 8-h late time-restricted eating with ER (eTRE + ER and lTRE + ER) compared to 12-h ER alone on body mass and other anthropometric and cardiometabolic risk factors in participants with overweight and obesity. METHODS: Participants (n = 108) were allocated to three different groups according to their personal chronotype: eTRE + ER (37 participants), lTRE + ER (37 participants) and ER (34 participants). Ninety-three participants completed the entire 3-month intervention (34 in eTRE + ER, 28 in lTRE + ER and 31 in ER). Anthropometric and cardiometabolic risk factors were measured at baseline and after 1, 2 and 3 months of the intervention. Sleep quality and quality of life were assessed at baseline and after 3 months of the intervention. ER was determined based on the individual's resting metabolic rate. Effects were analyzed using the per-protocol approach. RESULTS: Results showed a significant time main effect (p < 0.001), suggesting a decrease in body mass at the end of the 3-month intervention with a mean loss of -5.0 kg (95 % CI, -5.7, -4.3) for the eTRE + ER group, -4.4 kg (95 % CI, -5.2, -3.6) for the lTRE + ER group and -4.3 kg (95 % CI, -5.0, -3.6) for the ER group, with no significant difference between the groups (p = 0.319). eTRE + ER had greater improvements in fat mass (-1.2 % (95 % CI, -2.1, -0.2), p = 0.013) and fasting glucose (-0.35 mmol/L (95 % CI, -0.63, -0.06), p = 0.012) than participants in the lTRE + ER group and greater improvements in fat mass (-1.1 % (95 % CI, -2.0, -0.1), p = 0.022), metabolic age (-3 years (95 % CI, -5, -0), p = 0.028) and diastolic blood pressure (-4 mmHg (95 % CI, -8, -0), p = 0.033) than the participants in the ER group. No significant changes were found between the groups for the other parameters measured. CONCLUSIONS: There was no difference in body mass between the eTRE + ER, lTRE + ER and ER groups after 3 months of intervention. However, eTRE + ER showed a greater benefit for fasting blood glucose, certain anthropometric parameters and diastolic blood pressure compared to lTRE + ER and/or ER alone. Other anthropometric, biochemical and health-related parameters were not affected by eating window. TRIAL REGISTRATION: https://clinicaltrials.gov/study/NCT05730231.