The effect of time-restricted feeding on nutritional status in energy-restricted overweight and obese women

This study is a randomized controlled intervention study aiming to investigate the effects of a time-restricted eating pattern (16 hours of fasting and 8 hours of eating) on anthropometric measurements, body composition, and blood biochemical parameters in overweight and obese women following an energy-restricted diet. The study was conducted between June and November 2024 on a total of 38 volunteers referred by family health center (FHC) physicians with a recommendation for medical nutrition therapy at a private nutrition and diet counseling center operating in the city center of Gaziantep. Individuals were randomized into two groups, intervention (n=19) and control (n=19), using the minimization method, taking into account Body Mass Index (BMI, kg/m²) and age groups. The intervention group received time-restricted eating while on an energy-restricted diet, while the control group received only time-restricted eating during the eight-week follow-up period. The socio-demographic information of the individuals participating in the study (age, marital status, health status, dietary habits, etc.) was collected during the initial interview using the face-to-face interview method. Anthropometric and body composition measurements were taken by the researcher a total of five times: at the beginning of the study, at 15-day intervals, and at the end of the study (8th week) to monitor the individuals. Blood biochemical parameters (glucose, insulin, insulin resistance (HOMA–IR), lipid profile, liver and thyroid functions, etc.) were obtained twice from family health center (FHC) records at the beginning and end of the study. Three-day food consumption records were collected at the start of the study, and daily food consumption records were collected during the 8-week intervention period. All data were analyzed using the BEBIS 9.0 program. The IBM SPSS 23 software package was used for the analysis of all data. The feeding period was set at 11:00–19:00 for both groups, and consumption of non-energy liquids was permitted during the fasting period. Compared to baseline, there was a significant decrease in energy expenditure and Basal Metabolic Rate in the intervention group at weeks 4 and 8 (p<0.05). The waist circumference of the intervention group was lower than that of the control group, and there was a significant difference between waist circumference values at weeks 4 and 8 (p<0.05). There was a significant difference between the groups in terms of body fat mass and fat percentage at week 8 (p<0.05). A decrease in body fat mass and percentage was observed in the intervention group, while an increase was observed in the control group (p>0.05). There was a decrease in lean body mass in the control group (p<0.05). A significant decrease in muscle mass and total body fluid volume was observed in both groups (p<0.05). There were no significant differences between the groups in blood triglyceride, insulin, HOMA-IR, thyroid-stimulating hormone (TSH), and alanine aminotransferase (ALT) levels during the follow-up period (p>0.05). Triglyceride levels decreased significantly between baseline and week 8 in the intervention group (p<0.05). In conclusion, it has been determined that time-restricted eating combined with energy-restricted eating has positive effects, particularly on body composition and triglyceride levels. However, the observed decreases in the intake of certain micronutrients, such as folic acid, vitamin B6, and vitamin E, may pose a risk for nutritional deficiencies in the long term. The dietary program should be designed to meet macro- and micronutrient requirements, and individuals should be monitored regularly. The findings support the idea that time-restricted eating may be an alternative approach in obesity treatment; however, more comprehensive studies are needed to assess the long-term safety of this method.