Narrative reviewindependent cross-checkabstract checked I-SYS-106 standard review
Prolonged water fasting: short-term effects only
Efficacy and safety of prolonged water fasting: a narrative review of human trials.
Overview
Ezpeleta M et al.. Nutr Rev 2024 · PMID 37377031 · DOI 10.1093/nutrit/nuad081
Fasting 5-20 days lowered weight and blood pressure, but two-thirds of weight lost was lean mass and benefits faded.
Does the study support the specific claim? No · Methodological quality: low
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Review prolonged fasting.
- How was the study done?
Narrative review.
- How many people, animals or samples were studied?
Human trials.
- What was actually found?
Short-term changes, lean-mass loss.
- How large was the observed effect?
2-10% weight loss.
- What do the results mean in everyday life?
Not eating does not create lasting health.
- What are the study's limitations?
Small trials.
- What does it say about Elawady's specific claim?
Contradicts the claim.
- Do the results apply to Germany and Europe?
High.
- What can explicitly not be concluded from this study?
Long-term outcomes.
Scientific in-depth review
1. Full reference
- Authors
- Ezpeleta M et al.
- Journal
- Nutr Rev
- Year
- 2024
- Identifier
- PMID 37377031 DOI 10.1093/nutrit/nuad081
- Verification
- verified – PubMed efetch 2026-10-26 + Crossref
- Retracted
- no
- Corrections
- none
- Extent checked
- abstract only
- Conflicts of interest and funding
NIH grant (PubMed)
2. Research question
Efficacy and safety of prolonged water fasting (5-20 days)
3. Study design and population
- Study design
- Narrative review – Narrative review of human trials of prolonged water fasting
- Population
Human trial participants
- Country
International
- Period
Published 2024
- Sample size
not stated in abstract
- Inclusion and exclusion criteria
Human trials
4. Methods and endpoints
- Exposure / intervention
Prolonged water fasting
- Comparator
Baseline/controls
- Endpoints
Weight, BP, lipids, glycaemia, adverse events
- Statistical methods
Narrative
5. Actual results
- Results
Weight loss 2-10%, about two-thirds lean mass; BP decreased; lipids inconsistent; glycaemic markers improved in normoglycaemic adults but unchanged in type 1/2 diabetes; benefits disappeared 3-4 months after refeeding; adverse events included metabolic acidosis, headaches, insomnia, hunger.
- Absolute risks
not applicable
- Authors' conclusion
Prolonged fasting appears moderately safe and produces weight loss; sustained metabolic benefit uncertain.
6. Strengths
- Collects human trial data
7. Weaknesses
- Narrative
- Small trials
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
Narrative review.
9. Assessment of the statistical interpretation
Not applicable.
10. Relevance to the specific claim
Shows that going without food has some short-term metabolic effects but costs lean mass and does not produce lasting health.
11. Independent contrary findings
Supports that supervised short fasting can be tolerated - a limited kernel.
12. Transferability to Germany and Europe
High.
13. Overall methodological judgement
Contradicts 'zero inputs = infinite health'.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | low |
| Risk of bias | not assessable |
| Precision of results | not applicable |
| Directness | indirect |
| Reproducibility | unknown |
| Consistency with the overall evidence | mixed |
| Regional transferability | high |
| Adequacy of the interpretation (by the archive) | not applicable |
14. Open questions
15. Linked fact checks
- Zero inputs equal infinite health: complete abstention from any inputs achieves a state of a body that does not get sick; health is proportional to avoiding toxic inputs. – Studies contradicting or limiting the claim