The effect of early and delayed time-restricted feeding on weight loss, metabolic syndrome, and cardiovascular risk in obese individuals

This randomized controlled study was designed to determine the effects of an 8-week dietary intervention involving early time-restricted feeding (eTRF), delayed time-restricted feeding (dTRF), and unrestricted feeding schedules on anthropometric measurements, body composition, metabolic syndrome, and cardiovascular risk factors in obese adult women. A total of 36 female participants aged between 20 and 49 years with body mass index (BMI) values ranging from 30 to 35 kg/m² were included in the study. Participants were divided into three groups: the eTRF group (n=12), the dTRF group (n=12), and the control group (n=12). A one-day physical activity log was used to assess the participants' physical activity levels. Total energy expenditure was calculated for all participants, and a 25% energy restriction was applied to design individualized medical nutrition therapy. Anthropometric measurements and physical activity records of the individuals were obtained by the researcher, body compositions were determined, and biochemical findings were evaluated. The Pittsburgh Sleep Quality Index (PSQI), Morningness-Eveningness Questionnaire, and Diet Satisfaction Scale were administered to the participants. The mean age of the individuals participating in the study was found to be 35.05±0.56 years. At the end of the study, significant weight loss was observed in all groups (p<0.05). Weight loss was greater in the eTRF group compared to the other groups, and this difference was statistically significant (eTRF: -5.1±0.1 kg) (p<0.05). Significant reductions were observed in BMI, waist circumference, waist-to-height ratio, and body fat mass within each group (p<0.05); however, these reductions were not statistically significant between groups (p>0.05). Total cholesterol, LDL-C levels, and total cholesterol/HDL ratio decreased significantly in the eTRF group, whereas triglyceride levels showed a significant reduction in the dTRF group (p<0.05). Diastolic blood pressure decreased significantly in both the eTRF and dTRF groups (p<0.05). PSQI scores decreased significantly in the eTRF and control groups (p<0.05). The highest score on the Diet Satisfaction Questionnaire was observed in the control group (36.2±4.93), while the lowest was in the eTRF group (26.25±5.42) (p<0.05). The results of this study suggest that early time-restricted feeding may be effective in promoting weight loss and improving cardiovascular parameters. Additionally, the findings highlight the importance of evaluating the individual applicability of such dietary programs.