Animal studyindependent cross-checkabstract checked★ key study I-INS-120 in-depth review
Mice that cannot overproduce insulin do not get fat on a high-fat diet
Hyperinsulinemia drives diet-induced obesity independently of brain insulin production.
Overview
Mehran AE et al.. Cell Metab 2012 · PMID 23217255 · DOI 10.1016/j.cmet.2012.10.019
Mice genetically prevented from producing excess insulin were protected from diet-induced obesity.
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?
Test whether high insulin causes obesity in mice.
- How was the study done?
Genetic mouse experiment.
- How many people, animals or samples were studied?
Mice.
- What was actually found?
Less insulin = no diet-induced obesity.
- How large was the observed effect?
Not applicable.
- What do the results mean in everyday life?
Insulin can promote fat gain, at least in mice.
- What are the study's limitations?
Animal study.
- What does it say about Elawady's specific claim?
Partly supports a role of insulin; not 'only cause' in humans.
- Do the results apply to Germany and Europe?
Not directly transferable.
- What can explicitly not be concluded from this study?
Cannot show insulin is the only cause of human obesity.
Scientific in-depth review
1. Full reference
- Authors
- Mehran AE et al.
- Journal
- Cell Metab
- Year
- 2012
- Identifier
- PMID 23217255 DOI 10.1016/j.cmet.2012.10.019
- Verification
- verified – PubMed efetch 2026-10-26; Crossref 2026-10-26
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
Non-US government support (record).
2. Research question
Is hyperinsulinaemia a cause of diet-induced obesity?
3. Study design and population
- Study design
- Animal study – Genetic mouse model (reduced Ins1 gene dosage on Ins2-null background) on high-fat diet
- Population
Mice
- Country
Canada
- Period
Not applicable
- Sample size
Mouse cohorts (n not stated in abstract)
- Inclusion and exclusion criteria
Not applicable
4. Methods and endpoints
- Exposure / intervention
Normal Ins1 dosage (hyperinsulinaemia on high-fat diet)
- Comparator
Ins1 heterozygous mice (prevented hyperinsulinaemia)
- Endpoints
Body weight/fat, energy expenditure, adipose gene expression, liver fat
- Statistical methods
Group comparisons
5. Actual results
- Results
Mice with genetically prevented hyperinsulinaemia were completely protected from diet-induced obesity, had increased energy expenditure with uncoupling protein 1 expression in white fat, smaller adipocytes, less inflammation and less liver fat.
- Absolute risks
not reported
- Authors' conclusion
Pathological circulating hyperinsulinaemia drives diet-induced obesity and its complications.
6. Strengths
- Genetic manipulation gives causal inference in mice
7. Weaknesses
- Animal model
- Not transferable as 'only cause' in humans
8. Risk of bias
- Orienting tool
- none applicable
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- not assessable
- Rationale
Animal experiment.
9. Assessment of the statistical interpretation
Not applicable (abstract).
10. Relevance to the specific claim
Best experimental support for insulin as a driver of fat gain (in mice on a high-fat diet); does not show it is the only cause in humans.
11. Independent contrary findings
12. Transferability to Germany and Europe
Animal data; human relevance uncertain.
13. Overall methodological judgement
Supports a causal role in mice; overextended if read as 'only cause' in humans.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | moderate |
| Risk of bias | not assessable |
| Precision of results | not applicable |
| Directness | very indirect |
| Reproducibility | partly replicated |
| Consistency with the overall evidence | mixed |
| Regional transferability | unknown |
| Adequacy of the interpretation (by the archive) | not applicable |