Chronotype and Adherence to the Mediterranean Diet in Obesity: Results from the Opera Prevention Project

Chronotype is the attitude of a subject in determining individual circadian preference in behavioral and biological rhythm relative to the external light-dark cycle. Obesity and unhealthy eating habits have been associated with evening chronotype. The Mediterranean diet (MD) is a healthy nutritional pattern that has been reported to be associated with better health and quality of sleep. Thus, the aim of the study was to investigate the association of chronotype categories with adherence to the MD in a population of middle-aged Italian adults. This cross-sectional study included 172 middle-aged adults (71.5% females; 51.8 ± 15.7 years) that were consecutively enrolled in a campaign to prevent obesity called the OPERA (obesity, programs of nutrition, education, research and assessment of the best treatment) Prevention Project that was held in Naples on 11-13 October 2019. Anthropometric parameters, adherence to the MD and chronotype were studied. Chronotype was classified as morning in 58.1% of subjects, evening in 12.8% and intermediate in 28.1%. Our results demonstrated that individuals with evening chronotype, when compared to intermediate (p < 0.001) and morning chronotype (p < 0.001), were more prone to follow unhealthy lifestyle, performing less regular activity and being more frequently smokers. In addition, they showed the lowest adherence to the MD compared to morning (p < 0.001) and intermediate chronotypes (p < 0.001). The lower the chronotype score, the higher body mass index (BMI) values in the whole population (r = -0.158; p = 0.038), thus suggesting that evening chronotype was a common finding in subjects with obesity. In addition, positive correlations of chronotype score with age (r = 0.159; p = 0.037) and PREDIMED score (r = 0.656; p < 0.001) were found. The adherence to the MD, more than the intake of the single food items, was found to predict morning and evening chronotypes. In conclusion, evening chronotype was associated with unhealthy lifestyle and low adherence to the MD. Chronotype score was inversely associated to BMI and positively associated to age and adherence to the MD. Thus, the assessment of chronotype should be taken into account in the management of obesity and in the development of nutritional strategies.