Weight loss in patients with severe obesity after bariatric surgery - the potential role of the chrono-nutrition, chronotype and the circadian misalignment: a study protocol of the ChronoWise prospective cohort

Background Despite the potential effectiveness of bariatric surgery in promoting weight loss, a considerable proportion of patients still face the challenge of achieving optimal post-surgery outcomes. The timing of eating, in addition to the content of what is eaten, as well as chronotype and social jetlag (a marker of circadian misalignment), have been implicated in weight regulation. However, the current understanding of these chrono-related behaviours in individuals undergoing bariatric surgery is still scarce. Thus, this study aims to evaluate the role of chrono-nutrition, chronotype, and circadian misalignment in the weight-loss trajectory among individuals living with severe obesity who underwent bariatric surgery. Methods The ChronoWise project is a prospective single-centre cohort study designed to follow patients experiencing bariatric surgery at the Santo António Local Health Unit (ULSSA), Porto, Portugal. Participants will be recruited and evaluated at pre-surgery and followed-up over 3 and 6 months after surgery. The baseline evaluation will be conducted face-to-face during the hospital stay and by telephone or video call on the subsequent evaluations, following standard procedures. Data collection includes sociodemographics, food intake, chrono-nutrition behaviours, sleep time behaviour, sleep quality, screen time, physical activity and exercise behaviours, anthropometric measurements, and biochemical parameters. The ‘Munich Chronotype Questionnaire’ will be used to assess chronotype and social jet lag. Chrono-nutrition dimensions will be measured by the ‘Chrononutrition Profile—Questionnaire’ in all evaluations. Weight and height will be self-reported and retrieved from medical registries. trajectories of weight-loss will be obtained. Discussion This study will add important evidence on the role of chrono-nutrition, chronotype and social jetlag profile in weight-loss outcomes after bariatric surgery. Identifying novel approaches to change the paradigm of post-surgical weight management towards a tailored treatment aligned with circadian rhythm may be useful to strengthen the existing treatments and improve patients’ response to bariatric surgery.