Bariatric Surgery Outcomes in an Italian Single-Center Study: Does Chronotype Matter?

Background: Chronotype reflects an individual’s intrinsic circadian preference for the timing of daily behaviors, including sleep, eating, and physical activity. It influences not only biological rhythms but also lifestyle patterns that may impact metabolic health. In the context of bariatric surgery, numerous factors may affect postoperative outcomes such as weight loss and the risk of weight regain. Given the growing interest in chronobiology and its relevance to obesity management, this study aimed to explore whether chronotype is significantly associated with key weight loss outcomes following bariatric surgery at 6 and 12 months post-intervention. Methods: A total of 263 patients underwent bariatric surgery at a single center. Baseline assessments included anthropometric, biochemical, and behavioral evaluations, including chronotype categorization. Postoperative outcomes at 6 and 12 months included absolute weight, BMI, percentage of initial body weight loss (%IBWL), and percentage of excess body weight loss (ëWL). Results: There was no significant difference among the three different chronotypes (evening, intermediate, and morning chronotype) in terms of absolute weight, BMI, %EWL and %IBWL at 6 and 12 months after surgery. Conclusions: Our results suggest that chronotype does not seem to play a critical role in weight loss outcomes in bariatric surgery patients, characterized by severe obesity. Further studies are needed to more thoroughly assess the impact of chronotype on bariatric surgery outcomes and a more detailed characterization of chronotype itself in these patients could be decisive.