Research

Hormonal

Bariatric surgery (BS) induces initial weight loss through foregut exclusion-mediated hormonal upregulation of satiety hormones (GLP-1, PYY) and downregulation of ghrelin, but long-term weight regain (WR) is driven by the subsequent normalization or decline of these hormonal levels, alongside behavioral factors like dietary non-adherence and grazing.

If you had bariatric surgery and are regaining weight, recognize that your body's hormonal signals (hunger/satiety) may have changed back towards pre-surgery levels. This is a known biological mechanism, not just a personal failure. Focus on behavioral strategies (dietary counseling, monitoring) to counteract these biological drives, as hormonal interventions alone have shown mixed results.

ModerateSupportsMEDIUM confidence
Weight loss after BS is due to the anatomical exclusion of the foregut. This leads to a hormonal upregulation of pancreatic peptide YY, glucagon-like peptide-1 (GLP-1), and gastric inhibitory polypeptide hormones which promote satiety and minimize hunger, as well as down-regulation of ghrelin with subsequent decrease in food intake [40, 41]. With time, alterations in the levels of ghrelin, leptin, and incretins diminish, resulting in WR [42–44].
Walid El Ansari et al. · Obesity Surgery · 2021

Why this rating

This is a scoping review summarizing multiple studies; while mechanisms are well-cited, the review itself notes gaps in long-term evidence and small sample sizes for some hormonal markers.

Source

Weight Regain and Insufficient Weight Loss After Bariatric Surgery: Definitions, Prevalence, Mechanisms, Predictors, Prevention and Management Strategies, and Knowledge Gaps—a Scoping Review

Walid El Ansari et al. · Obesity Surgery · 2021

DOI 10.1007/s11695-020-05160-5

narrative_reviewCited 456×
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DOI resolved against Crossref · corpus check 2026-06-10

This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →