Case series / case reportindependent cross-checkfull text checked★ key study I-FAST-125 standard review
Five days without food or water
Hypoglycemia compensation mechanisms in dry fasting.
Overview
Papagiannopoulos-Vatopaidinos IE et al.. Metabol Open 2025 · PMID 40585323 · DOI 10.1016/j.metop.2025.100363
Ten healthy people under supervision coped with a five-day dry fast, but the researchers say medical supervision is essential.
Does the study support the specific claim? Partly · Methodological quality: very low
Plain-language summary
Study explained simply
- What did the researchers want to find out?
Describe body responses to dry fasting.
- How was the study done?
Daily measurements in 10 people.
- How many people, animals or samples were studied?
10 healthy Greek adults.
- What was actually found?
Insulin fell; glucose dipped then recovered; LDL rose; GFR increased.
- How large was the observed effect?
Not applicable.
- What do the results mean in everyday life?
Dry fasting is not safe without medical supervision and healthy kidneys.
- What are the study's limitations?
Tiny, uncontrolled, no prospective ethics approval.
- What does it say about Elawady's specific claim?
Weakly supports tolerability; does not support unsupervised weekly 3-day dry fasting.
- Do the results apply to Germany and Europe?
Applies; same physiology.
- What can explicitly not be concluded from this study?
Safety in people with disease, in heat, or repeated weekly.
Scientific in-depth review
1. Full reference
- Authors
- Papagiannopoulos-Vatopaidinos IE et al.
- Journal
- Metabol Open
- Year
- 2025
- Identifier
- PMID 40585323 DOI 10.1016/j.metop.2025.100363
- Verification
- verified – PubMed efetch 2026-10-26; Crossref update-to/updated-by check
- Retracted
- no
- Corrections
- none
- Extent checked
- full text
- Conflicts of interest and funding
No conflicts declared; no grant funding. Ethics: data collected May 2014 when no bioethics committee was active at the cooperating institute (an IRB was first constituted in 2016), i.e. no prospective ethics approval.
2. Research question
How do glucose and hormones behave during a 5-day dry fast?
3. Study design and population
- Study design
- Case series / case report – Uncontrolled physiological case series, 5-day dry fast with daily measurements
- Population
Adults without medication, normal glucose metabolism, no diabetes, no cardiovascular disease, recruited from a medical office
- Country
Greece
- Period
Data collected May 2014
- Sample size
10 (3 men, 7 women; age 30-65)
- Inclusion and exclusion criteria
not stated in abstract
4. Methods and endpoints
- Exposure / intervention
5-day dry fast (no food or water)
- Comparator
Baseline
- Endpoints
Weight, glucose, insulin, HOMA-IR, GFR, hormones, lipids, enzymes
- Statistical methods
Daily repeated measures
5. Actual results
- Results
Weight, body circumferences and thyroid hormones decreased to minima on day 5; insulin and HOMA-IR decreased with minima on day 4; GH, cholesterol, LDL-C and acetoacetate increased; glucagon, IGF-1 and GFR increased; glucose showed a biphasic profile with a minimum on day 3.
- Absolute risks
not reported
- Authors' conclusion
Comprehensive description of hypoglycaemia compensation in dry fasting; DF decreased insulin resistance. Authors state that even compensated, hypoglycaemia, hypovolaemia and hypertonicity make medical supervision obligatory and limit application to some days; compensating mechanisms require intact endocrine and renal function.
6. Strengths
- Daily detailed measurements
- Full text read
7. Weaknesses
- 10 participants, no control
- No prospective ethics committee approval
- LDL-C rose
8. Risk of bias
- Orienting tool
- none applicable
- Type of assessment
- simplified assessment (abstract only)
- Full formal assessment
- no
- Overall risk of bias
- high
- Rationale
Tiny uncontrolled series.
9. Assessment of the statistical interpretation
Descriptive only; no safety conclusions possible from 10 people.
10. Relevance to the specific claim
Weak support that healthy people under supervision can compensate a 5-day dry fast; authors themselves require medical supervision and intact kidneys/hormones, contrary to recommending weekly 3-day dry fasts to the public.
11. Independent contrary findings
12. Transferability to Germany and Europe
Universal biology; applies in Europe and Egypt.
13. Overall methodological judgement
Very weak support; it highlights the conditions under which dry fasting was tolerated.
| Multidimensional assessment | |
|---|---|
| Authenticity of the source | verified |
| Methodological quality | very low |
| Risk of bias | high |
| Precision of results | low |
| Directness | direct |
| Reproducibility | not replicated |
| Consistency with the overall evidence | unknown |
| Regional transferability | low |
| Adequacy of the interpretation (by the archive) | not applicable |