Effect of feeding timing on circadian RHYTHM markers in obese individuals under WEİGHT LOSS DİET

Feeding time is a powerful synchronizer for peripheral oscillators that do not have a clear synchronizing effect on the suprachiasmatic clock. Limiting daily food intake to a specific time period has received a lot of attention in recent years as an alternative to energy restriction to assist weight loss and improve metabolic health. This study was planned and conducted to examine the effect of feeding time on circadian rhythm markers in individuals under weight loss diet. The study was carried out with volunteers who agreed to participate in the study among female individuals who applied to the Baskent University Ankara Hospital Endocrine Polyclinic between September 2019 and October 2020. This randomized crossover design study was conducted between the ages of 20 and 50, with a body mass index between 25 and 35 kg/m2, without any chronic disease, no a diet history in the last 6 months, and had regular night sleep (bedtime 22:00-00.00; awakening time 06: 00- 08:00), a total of 29 female individuals were included. Individuals were divided into 2 groups by randomization method, Group I (n=15) and Group II (n=14). Individual nutrition plans with energy restriction aimed at losing weight have been created for individuals. In the first 4 weeks, individuals in Group I were given "time-restricted feeding" diet intervention during from sunrise to sunset period, while individuals in Group 2 were given the "extended feeding" diet intervention, which gave them the opportunity to eat at any time of the day. At the end of the first intervention period, the groups were taken into a 1-week washout period and then extended feeding was given to the individuals in Group I and time restricted feeding was given to the individuals in Group II. The anthropometric measurements and biochemical parameters of the individuals were evaluated at the beginning, the 4th week and the end of the study. A total of 20 individuals carried out both periods of the dietary intervention. While examining the changes in anthropometric measurement, body analysis and skinfold thicknesses within the groups over time, mean change in body weight, body mass index, waist circumference, hip circumference, waist/height ratio, biceps skinfold thickness, triceps skinfold thickness and body fat mass in the both diet interventions were found to be statistically significant (p<0.05), however, mean changes in body muscle mass and body water mass were statistically significant only in the time-restricted feeding intervention (p<0.05). Serum fasting blood glucose observed a significant decrease in extended feeding intervention (p<0.05). The decrease in serum HDL - cholesterol and leptin levels was found to be statistically significant in time-restricted feeding intervention (p<0.05). The relationship between different diet interventions and biochemical parameters were found no statistically significant (p>0.05). As a result, although time-restricted feeding provided more changes on anthropometric measurements than extended feeding was no differences between nutritional interventions. In addition to adequate and balanced nutrition programs, the application of a time restricted feeding approach in the treatment of obesity may provide an additional benefit in weight loss.