Weight-loss interventions in gastrointestinal and liver diseases: a narrative review of GLP-1 based therapies, bariatric surgery, and endoscopic approaches

Obesity and metabolic dysfunction are increasingly prevalent in patients with diverse gastrointestinal and liver diseases and contribute to disease progression, treatment response, and long-term clinical outcomes. In parallel, the therapeutic landscape for obesity has expanded rapidly, with growing use of incretin receptor agonists (RA), including glucagon-like peptide-1 (GLP1)-RA, bariatric surgery, and endoscopic bariatric therapies. Understanding how these weight-loss interventions influence gastrointestinal disease activity, safety, and malignancy risk is essential for clinical decision-making. This narrative review synthesizes current evidence on the effects of obesity as well as weight-loss therapies across a spectrum of gastrointestinal and liver conditions, including metabolic dysfunction-associated steatotic liver disease (MASLD), inflammatory bowel disease (IBD), gastroesophageal reflux disease, celiac disease, gastrointestinal malignancies, and dumping syndrome. We summarize data from randomized trials, observational cohorts, and meta-analyses evaluating clinical outcomes, disease activity, adverse events, and cancer risk. In MASLD, GLP1-RA and bariatric surgery improve hepatic steatosis and steatohepatitis without aggravation of fibrosis. Fibrosis outcomes are most strongly influenced by sustained weight loss and improvements in insulin resistance. In IBD, obesity (particularly increased visceral fat) may negatively impact response to biologics; however, observational data suggest that GLP1-RA are not associated with increased IBD disease activity and may be associated with favorable clinical outcomes in selected patients with obesity. Bariatric surgery—particularly sleeve gastrectomy—may improve IBD control in carefully selected patients. Data on endoscopic bariatric therapies in IBD are limited but may be effective in selected patients. Gastrointestinal malignancies have increased prevalence in obesity, including esophageal, pancreatic, liver, and colorectal cancers. Current randomized and observational data do not demonstrate consistently increased cancer risk with GLP-1 based therapies, while bariatric surgery may be associated with reduced risk of selected obesity-related cancers. Evidence linking endoscopic bariatric therapies to malignancy risk is currently lacking. Dumping syndrome is a complication of bariatric surgery, but has not been reported following endoscopic bariatric therapies, likely due to delayed gastric emptying. Collectively, weight-loss therapies are increasingly important in the management of gastrointestinal and liver diseases. Ongoing studies and longer-term follow-up are needed to clarify durability of benefit, procedure-specific risks, and optimal patient selection for GLP-1 based therapies.