Combined in-person and home-based circuit exercise improves body composition and hormonal profiles in patients with post-bariatric weight regain: a genotype-stratified single-arm interventional study

Purpose: Weight regain following metabolic/bariatric surgery (MBS) is a common challenge that may compromise the long-term benefits of surgery.This study evaluated the effects of an 8-week circuit training and dietary counseling program on body composition and obesity-related hormones in patients with early post-bariatric weight regain and assessed the influence of FTO rs9939609 genotype.Methods: This prospective, single-arm intervention enrolled 16 adults with ≥5% weight regain after MBS.Participants completed a structured hybrid program consisting of weekly supervised and home-based circuit training, alongside standardized dietary guidance.Anthropometric, hormonal, and metabolic parameters were measured before and after the intervention.Participants were genotyped for FTO rs9939609 and categorized into TT (non-risk) and AA/AT (risk allele) groups.Results: After 8 weeks, participants showed significant reductions in body mass index (-4.4%,P < 0.001), waist circumference (-5.8%,P = 0.001), and fat mass (-7.1%,P = 0.004), whereas muscle mass decreased modestly (-2.7%, P = 0.056).Leptin (-29.8%,P = 0.002), ghrelin (-10.2%,P = 0.002), and insulin (-14.5%,P = 0.039) levels also declined significantly.Although the AA/AT group exhibited higher absolute adiposity than the TT group both pre-and postintervention, percentage changes in anthropometric parameters did not significantly differ between the 2 groups.Conclusion: A structured hybrid exercise and dietary program was effective in reversing early weight regain and improving hormonal profiles after MBS.The FTO risk allele was associated with greater baseline obesity but did not attenuate response to the intervention.