A shorter time-restricted eating window leads to greater weight loss.A pooled analysis of data from five studies shows that a shorter time-restricted eating (TRE) window leads to greater weight loss.
Participants on the 8-hr TRE window had greater weight loss compared with those on the 10-hr (difference, 1.02 kg; p=0.09) and 12-hr TRE windows (difference, 1.66 kg; p=0.02) and the control group (difference, 2.25 kg; p=0.002). The associations remained significant after adjusting for age, sex, and BMI at baseline. [Nutr Diabetes 2026;doi.org/10.1038/s41387-026-00467-1]
Greater weight loss was also associated with shorter eating windows (0.27 kg/1-hr reduction; p=0.02) and greater reductions in habitual eating windows after accounting for baseline eating window duration (0.26 kg/1-hr reduction; p=0.03). However, these associations were attenuated after adjusting for confounders, potentially due to the limited sample size.
“Our findings support the concept that the duration of the eating window per se is a determinant of weight loss, independent of caloric prescriptions,” the researchers said.
Shorter eating windows and greater reductions from habitual eating duration may facilitate spontaneous energy restriction by limiting opportunities for late-day and energy-dense food intake, while simultaneously extending the fasting period and promoting metabolic flexibility. [Cell Metab 2024;36:301-314; Nutrients 2021;13:1042; Cell Metab 2015;22:789-798]
The prolonged fasting periods during TRE may also contribute to weight loss by increasing fat oxidation and improving glucose metabolism and insulin sensitivity. [N Engl J Med 2019;381:2541-2551; Int J Mol Sci 2019;20:1911]
Achievable target for weight management
This analysis included 124 adults (mean age 47.1 years, 67 percent women, baseline eating duration 15 hrs) who participated in one of five TRE trials. They were assigned to either the TRE (n=95) or the control group (ie, eating window remaining ≥14 hrs; n=29).
Participants in the TRE group were instructed to restrict their eating window to 8, 10, or 12 hrs, with no limit to energy intake or dietary quality. Control participants followed habitual diets or received brief nutritional counselling and/or written guidance on healthy eating guidelines.
“[O]ur analysis provided novel insights and shows that greater reductions in habitual eating windows are associated with greater weight loss … but larger, adequately powered studies are required to confirm the magnitude and independence of this effect,” the researchers said.
“From a clinical and public health perspective, these findings may provide a pragmatic and achievable target for weight management. This flexibility may enhance adherence and long-term sustainability, particularly in real-world settings where socio-familial and occupational constraints limit adherence to strict TRE eating windows,” they said.
The investigators called for further studies evaluating data from other TRE trials with longer follow-up periods, more diverse populations, and a wider range of eating-window durations (ie, <8 hrs).
Eating windows <8 hrs may pose adherence challenges and reduce long-term compliance. [Nat Rev Endocrinol 2022;18:309-321] Moreover, severely restricted TRE windows may offset beneficial metabolic adaptations and increase hunger. [Am J Clin Nutr 2007;85:981-988; Metabolism 2007;56:1729-1734]
“Integrating objective dietary intake, physical activity and sleep measures, and information on individual chronotype will be critical for disentangling the relative contributions of eating-window duration, caloric intake, and circadian alignment to changes in body weight and metabolic outcomes,” they said.