Meta-analysisindependent cross-checkabstract checked I-BAR-147 standard review
Meta-analysis: gut hormones after sleeve
Effect of Sleeve Gastrectomy on Ghrelin, GLP-1, PYY, and GIP Gut Hormones: A Systematic Review and Meta-analysis.
Overview
McCarty et al.. Ann Surg 2020 · PMID 31592891 · DOI 10.1097/SLA.0000000000003614
After sleeve the hunger hormone ghrelin fell and satiety hormones GLP-1 and PYY rose.
Does the study support the specific claim? Partly · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Hormone changes after SG
- How was the study done?
Meta-analysis
- How many people, animals or samples were studied?
653
- What was actually found?
Ghrelin down, GLP-1/PYY up
- How large was the observed effect?
Hedges' g -1.49 (ghrelin)
- What do the results mean in everyday life?
The stomach is a hormone organ; surgery changes it
- What are the study's limitations?
Short follow-up
- What does it say about Elawady's specific claim?
Premise correct, conclusion not
- Do the results apply to Germany and Europe?
Applicable
- What can explicitly not be concluded from this study?
Long-term health effects
Scientific in-depth review
1. Full reference
- Authors
- McCarty et al.
- Journal
- Ann Surg
- Year
- 2020
- Identifier
- PMID 31592891 DOI 10.1097/SLA.0000000000003614
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref API
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
How do ghrelin, GLP-1, PYY and GIP change after sleeve gastrectomy?
3. Study design and population
- Study design
- Meta-analysis – Systematic review and meta-analysis (RCTs and prospective studies)
- Population
Patients undergoing SG
- Country
Multinational
- Period
Search to 1 April 2019
- Sample size
28 studies, 653 patients
- Inclusion and exclusion criteria
RCTs and prospective studies with pre/post hormone measures
4. Methods and endpoints
- Exposure / intervention
Sleeve gastrectomy
- Comparator
Preoperative
- Endpoints
Fasting ghrelin, postprandial GLP-1, PYY, fasting GIP
- Statistical methods
Hedges' g, random effects
5. Actual results
- Results
Ghrelin decreased (g -1.486, -1.884 to -1.089; I2 91.95%); GLP-1 increased (g 1.095, 0.509 to 1.642); PYY increased (g 1.396, 0.781 to 2.011); GIP unchanged (g -0.213, -1.019 to 0.592). Mean follow-up 11.7 months.
- Absolute risks
not applicable
- Authors' conclusion
Fasting ghrelin decreased and postprandial GLP-1 and PYY increased after SG; GIP unchanged.
6. Strengths
- Quantitative synthesis of hormone changes
7. Weaknesses
- Short follow-up
- High heterogeneity
- Small total sample
8. Risk of bias
- Orienting tool
- AMSTAR 2
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- some concerns
- Rationale
Abstract only.
9. Assessment of the statistical interpretation
Large standardised effects with high heterogeneity.
10. Relevance to the specific claim
Confirms Elawady's premise that the stomach is an endocrine organ whose hormone output changes after sleeve; these changes are, however, part of how the operation improves weight and glucose, not evidence of harm.
11. Independent contrary findings
12. Transferability to Germany and Europe
International.
13. Overall methodological judgement
Supports the physiological premise; does not support the conclusion of harm.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | some concerns |
| Precision of results | moderate |
| Directness | direct |
| Reproducibility | replicated |
| Consistency with the overall evidence | consistent |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
Long-term hormone adaptation.