A shorter eating window of time-restricted eating is more beneficial for weight loss: a pooled analysis of individual data from five trials

Abstract Background/Objectives To explore the effects of different time-restricted eating (TRE) windows on body weight, blood pressure, fasting plasma glucose, and lipid profile. Methods We conducted a pooled analysis of individual participant data from five TRE trials lasting 3-6 months and timestamped food/drink ingestion recorded with the myCircadianClock app. Participants in the control arms followed habitual ad libitum diets or received brief nutritional counseling and/or written guidance on healthy eating guidelines. Regression models assessed the associations between TRE and cardiometabolic outcomes according to allocated (8 h, 10 h, 12 h, or control) and actual eating windows (measured during follow-up), and changes in habitual eating duration. Results We included 124 adults (67% women; mean age 47.1 ± SD 13.2 years; baseline eating duration 15 h 02 ± 1 h 24) who were assigned to TRE ( n = 95) or control intervention ( n = 29). Those allocated to 8 h-TRE experienced greater weight loss than those on 12 h-TRE (difference: 1.66 Kg loss, 95%CI 0.22–3.10, p = 0.02) and controls (difference: 2.25 Kg loss, 95%CI 0.84–3.66, p = 0.002), with a trend towards greater weight loss versus 10 h-TRE (mean difference: 1.02 Kg; 95% CI: −0.16 to 2.21; p = 0.09). These associations generally persisted after adjustment for age, sex, and baseline BMI. Greater weight loss was associated with shorter eating windows (0.27 Kg, 95%CI 0.05–0.49, per 1h-reduction, p = 0.02) and greater reductions in habitual eating windows after accounting for baseline eating window duration (0.26 Kg, 95%CI 0.03–0.49, per 1h-reduction, p = 0.03). These associations were attenuated after adjustments for major confounders, potentially due to the limited sample size. Conclusions In this pooled analysis of individual data from five TRE trials, shorter eating windows and greater reductions in habitual eating windows were associated with modestly greater weight loss in unadjusted analyses, although some associations were attenuated after adjustments. Larger, longer-term TRE trials across a wider range of eating windows are needed to confirm these findings.