Background: Chronotype is the expression of the timing of circadian rhythmicity of a subject, and three categories of chronotype have been identified: morning, evening and intermediate chronotype. Subjects with morning chronotype prefer to carry out most of their daily activities in the morning while subjects with evening chronotype perform most of their daily activities in the second half of the day. Intermediate chronotype is in an intermediate position between the above reported categories. Recently evening chronotype has been associated with an increased risk of developing chronic diseases. Thus, the aim of this manuscript is to review the current evidence on the role of chronotype categories on the risk of developing obesity and the most common obesity-related comorbidities (cardiometabolic and neoplastic complications). Summary: Subjects with evening chronotype have been reported to be at high risk of developing obesity and this was mostly due to the tendency of these subjects to follow unhealthy lifestyle mostly characterized by sedentary behavior and high intake of unhealthy food. In addition, sleep disturbances are a common finding in subjects with evening chronotype that in turn could further contribute to the risk of obesity. The impairment of insulin sensitivity, melatonin, adiponectin and clock genes function along with increase of leptin secretion detected in subjects with evening chronotype could also represent a favorable milieu for the onset of obesity-related cancer. The current evidence are limited to breast, prostate and endometrial cancer. Key Messages: The chronotype categories could be easy assessed in subjects with obesity and at the same time provide an important information on an additional risk factor predisposing to the onset of obesity-related comorbidities. Since chronotype could be modified through a behavioral-driven approach thus potentiating the efficacy of anti-obesity treatment, the assessment of chronotype categories should be included in the management of obesity.

The Author(s). Published by S. Karger AG, Basel