Comparison of the effects of two different dietary approaches in obese individuals with the evening chronotype

Obesity is chronic, relapsing multifactorial disease that has a rising trend globally. Individual behavioral differences due to the timing of circadian rhythms create the chronotype diversity. People with evening chronotype have a higher risk for obesity than other individuals. The role of medical nutrition therapy in obesity management is highly significant. The aim of this study is to compare the differences between two different diets applied to individuals with evening chronotype and obesity in regards to anthropometric measurements taken before and after the beginning of dietery approaches. The research was conducted between March 2023 and May 2023 with 40 volunteers having evening chronotype and obesity, who applied to the Diabetes and Obesity Outpatient Clinic at Istanbul University-Cerrahpaşa Faculty of Medicine. Participants were divided into two groups with the two different diets whose effects on anthropometric measurements were to be compared. The daily calorie intake distribution of those in the Morning Group (n=20) was planned as (breakfast/lunch/dinner; %45/%35/%20), and those in the Evening Group (n=20) as (breakfast/lunch/dinner; %20/%35/%45). Participants were followed by a dietitian for 4 weeks, and the changes in anthropometric measurements taken during the first and last interview were recorded. Statistically significant (p<0.001) differences between the pre-diet and post-diet body weight, Body Mass Index (BMI), Waist Circumference (WC), Hip Circumference, Waist/Hip circumference ratio (WHR), Fat Mass (FM), Fat Free Mass (FFM) and body fat ratio measurements among Morning and Evening group participants were observed. In our study, when the changes in anthropometric measurements between the groups were compared, a statistically significant difference was found between the groups in body weight (4,58±1,06 kg; 3,81±1,13 kg), BMI (1,78±0,43kg/m²; 1,38±0,42 kg/m²), WC (4,22±1,18 cm; 3,45±1,23 cm), body fat mass (3,16±0,82 kg; 2,45±0,74 kg) and body fat ratio (%1,60±0,56; %1,07±0,53) (p<0.05). There is no statistically significant difference when hip circumference (2,22±1,06 cm; 1,65±0,93 cm), WHR (0,01±0,01; 0,01±0,01) and FFM (1,42±0,50 kg; 1,36±0,58 kg) changes are compared between groups (p>0.05). According to the results of our study, it is thought that it would be beneficial to have a high daily calorie intake in the morning meal when planning medical nutrition treatment for individuals with obesity and evening chronotype.