Systematic reviewindependent cross-checkabstract checked★ key study I-FAST-114 in-depth review

Cochrane review of intermittent fasting

Intermittent fasting for adults with overweight or obesity.

Overview

Garegnani LI et al.. Cochrane Database Syst Rev 2026 · PMID 41692034 · DOI 10.1002/14651858.CD015610.pub2

Intermittent fasting led to about the same weight loss as standard diet advice over up to 12 months.

Does the study support the specific claim? No · Methodological quality: high

Study explained simply

What did the researchers want to find out?: Assess IF for weight loss.
How was the study done?: Cochrane review of 22 RCTs.
How many people, animals or samples were studied?: 1,995 adults with overweight/obesity.
What was actually found?: No meaningful difference vs dietary advice.
How large was the observed effect?: MD -0.33% (-0.92 to 0.26).
What do the results mean in everyday life?: Fasting is one way to eat less, not a better way.
What are the study's limitations?: Short-term; risk of bias.
What does it say about Elawady's specific claim?: Contradicts 'the healthy way to eat'.
Do the results apply to Germany and Europe?: Applies; same physiology.
What can explicitly not be concluded from this study?: Long-term effects; effects in people of normal weight.

Authors: Garegnani LI et al.
Journal: Cochrane Database Syst Rev
Year: 2026
Identifier: PMID 41692034 DOI 10.1002/14651858.CD015610.pub2
Verification: verified – PubMed efetch 2026-10-26; Crossref update-to/updated-by check
Retracted: no
Corrections: none
Extent checked: abstract only
Conflicts of interest and funding: No dedicated funding; author declarations 'none known' for most (stated).

Benefits and harms of intermittent fasting vs regular dietary advice or no intervention in adults with overweight/obesity.

Study design: Systematic review – Cochrane systematic review and meta-analysis of RCTs (RoB 2, GRADE)
Population: Adults with overweight or obesity
Country: North America, Australia, China, Denmark, Germany, Norway, Brazil
Period: Search to 5 Nov 2024
Sample size: 22 RCTs, 1995 participants
Inclusion and exclusion criteria: RCTs >=4 weeks intervention, >=6 months follow-up; cross-over excluded

Exposure / intervention: TRE, periodic, ADF, modified ADF
Comparator: Regular dietary advice; no intervention/waiting list
Endpoints: Weight loss, quality of life, satisfaction, diabetes status, adverse events
Statistical methods: Random effects; GRADE

Results: Vs regular dietary advice: % weight loss MD -0.33 (95% CI -0.92 to 0.26; 21 studies, 1430 participants; low certainty); achieving 5% loss RR 0.98 (0.82 to 1.18; very low); QoL SMD 0.11 (-0.27 to 0.49); adverse events RR 1.45 (0.64 to 3.28; very low). Vs no intervention: % weight loss MD -3.42 (-4.95 to -1.90; moderate certainty).
Absolute risks: not reported
Authors' conclusion: Compared with regular dietary advice, intermittent fasting may result in little to no difference in weight loss or quality of life; adverse events very uncertain; evidence short-term (<=12 months).

Orienting tool: AMSTAR 2
Type of assessment: simplified assessment (abstract only)
Full formal assessment: no
Overall risk of bias: low
Rationale: High-quality review; certainty limited by primary-study risk of bias.

CIs symmetric; adverse event RR imprecise. See stats/I-FAST-114_cochrane_if.py.

Most recent Cochrane evidence: intermittent fasting is not better than standard dietary advice.

Universal biology; applies in Europe and Egypt.

High-quality review contradicting any claim that fasting patterns are uniquely healthy.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	high
Risk of bias	low
Precision of results	moderate
Directness	direct
Reproducibility	replicated
Consistency with the overall evidence	consistent
Regional transferability	moderate
Adequacy of the interpretation (by the archive)	not applicable