Research
Hormonal
Gastric bypass surgery alters gut hormone levels (low ghrelin, high GLP-1/PYY) in a way that attenuates appetite, contributing to its efficacy as a treatment for obesity.
Gastric bypass surgery works partly by changing gut hormones to reduce appetite (low ghrelin, high GLP-1/PYY). This hormonal shift helps explain why surgery is often more effective than diet/exercise alone for long-term weight loss.
GoodSupportsHIGH confidence
Following gastric bypass surgery, levels of ghrelin are extremely low, while GLP-1 and PYY are elevated, which should attenuate appetite. These findings raise the possibility that the gastric bypass procedure reduces weight, at least in part, by altering the production and/or release of these mediators of appetite.
Why this rating
Supported by studies cited in the review.
Source
Physiological adaptations to weight loss and factors favouring weight regain
Frank L. Greenway · International Journal of Obesity · 2015
DOI 10.1038/ijo.2015.59
narrative_reviewCited 416×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
More from this paper
- Physiological adaptations to weight loss, including hormonal shifts and reduced energy expenditure, actively favor weight regain, making long-term maintenance difficult without medical intervention.Good
- Diet-induced weight loss causes persistent perturbations in circulating appetite hormones (increased ghrelin, decreased leptin/PYY/GLP-1) that favor weight regain and persist for at least one year.Good
- Weight loss leads to a disproportionate decrease in Resting Energy Expenditure (REE) compared to the loss of body mass, creating a metabolic adaptation that favors weight regain.Good
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