Meta-analysisindependent cross-checkabstract only checked I-SYS-06 standard review
Exercise alone leads to only small weight loss
Isolated aerobic exercise and weight loss: a systematic review and meta-analysis of randomized controlled trials.
Overview
Thorogood A et al.. Am J Med 2011 · PMID 21787904 · DOI 10.1016/j.amjmed.2011.02.037
6-12 months of aerobic exercise reduced weight by about 1.6-1.7 kg.
Does the study support the specific claim? No · Methodological quality: moderate
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Exercise-only weight effect.
- How was the study done?
Meta-analysis of RCTs.
- How many people, animals or samples were studied?
1,847.
- What was actually found?
Modest loss.
- How large was the observed effect?
-1.7 kg at 12 months.
- What do the results mean in everyday life?
Exercise is healthy, but weight control needs diet too.
- What are the study's limitations?
Few trials.
- What does it say about Elawady's specific claim?
Contradicts 'inactivity is the origin'.
- Do the results apply to Germany and Europe?
High.
- What can explicitly not be concluded from this study?
Role of inactivity in causing weight gain over decades.
Scientific in-depth review
1. Full reference
- Authors
- Thorogood A et al.
- Journal
- Am J Med
- Year
- 2011
- Identifier
- PMID 21787904 DOI 10.1016/j.amjmed.2011.02.037
- Verification
- verified – PubMed esummary + efetch 2026-10-25
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
not stated in abstract
2. Research question
Weight loss from isolated aerobic exercise.
3. Study design and population
- Study design
- Meta-analysis – Systematic review and meta-analysis of RCTs
- Population
Overweight/obese adults
- Country
International
- Period
To January 2010
- Sample size
14 trials; 1,847 patients
- Inclusion and exclusion criteria
RCTs of isolated aerobic exercise
4. Methods and endpoints
- Exposure / intervention
Aerobic exercise programmes 6-12 months
- Comparator
Control
- Endpoints
Weight, waist circumference
- Statistical methods
Weighted mean difference
5. Actual results
- Results
6 months: -1.6 kg (95% CI -1.64 to -1.56); 12 months: -1.7 kg (-2.29 to -1.11); waist -2 cm.
- Absolute risks
not applicable
- Authors' conclusion
Isolated aerobic exercise is not an effective weight-loss therapy alone, though it has other benefits and helps combined with diet.
6. Strengths
- RCT-based
7. Weaknesses
- Few trials
- Moderate exercise doses
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
Limited number of trials.
9. Assessment of the statistical interpretation
Exercise alone yields modest weight loss.
10. Relevance to the specific claim
Contradicts that lack of movement is the main origin of excess weight.
11. Independent contrary findings
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Supports energy intake as main lever.
| 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
15. Linked fact checks
- Lack of movement is the origin (main cause) of weight accumulation. – Studies contradicting or limiting the claim