Evaluating the Effect of Chronotype on Meal Timing and Obesity in Iranian Housewives: A Cross-Sectional Study

Background and Objective: Recent studies have shown a relationship between energy regulation and the circadian rhythm at behavioral, molecular, and physiological levels. The present study investigated the effect of chronotype on meal timing and obesity in Iranian housewives. Materials and Methods: This cross-sectional study was carried out using a convenience-sampling method through the participation of housewives living in Ahvaz in 2018. Anthropometric information was collected. To assess food intake timing, energy intake and sleep patterns during seven days of normal living were recorded by the researchers. Dietary information was obtained using a 24-h recall questionnaire and analyzed by Nut IV software. The morningness-eveningness questionnaire (MEQ) was used to determine chronotypes. Results: There was a significant difference between the morning and evening groups in terms of the timing of lunch (P = 0.004) and mid-afternoon snacks (P = 0.04). There was no significant difference between mean energy intake in the morning and evening chronotypes in women who were overweight or obese (P = 0.31). There was also no significant difference between morning and evening chronotypes in terms of the percentage of energy intake of meals and snacks (P > 0.05). The only significant difference detected between morning and evening chronotypes in normal-weight women was for the percentage of energy intake after 3:00 p.m. (P = 0.008). Conclusion: The present study showed no effect of chronotype on obesity. However, energy intake calculations were based on self-reports, which could have led to information bias. Therefore, we suggest  that researchers carry out clinical trials while controlling food intake and considering meal timing in future studies.