Fasting Evidence

Evidence map

Fasting safety: what the evidence base looks like

10 publications, 2 of them trials and 6 syntheses. This page describes the shape of that literature rather than summarising its conclusions.

Updated 4 min read 10 citations

What the evidence on fasting safety is made of Of 10 publications on this topic, the breakdown by study type: 6 meta-analysis, 2 randomised trial, 2 review. 622meta-analysis (6)randomised trial (2)review (2)
10 publications, by study type. Volume is not strength — the same count can be a settled question or a pile of commentary, and which one it is depends almost entirely on this breakdown. Harvested from PubMed and Crossref; publication type as recorded by the source.

What this literature is made of

The synthesis is ahead of the primary literature here — reviews and meta-analyses drawing on a modest number of underlying studies. Treat confident conclusions with the caution the sample size deserves.

The distinction that matters most is between synthesis and primary research. A meta-analysis pools trials and is the closest thing to a settled answer a field produces. A narrative review is one group's reading of the same material and can be selective without being dishonest. Counting them together, which most citation counts do, obscures exactly the thing you want to know.

When the fasting safety literature was published Publication years for the 10 papers on this topic, grouped into bands from before 2015 through to 2023 onwards. 2023 onwards6 papers2020-20224 papers
Still active. The most recent paper here is from 2026, so this is a field where an answer written today may not hold for long. Publication years as recorded by PubMed and Crossref.

How this page is built

Everything above is computed from the citations this site harvested from PubMed and Crossref, not written by hand. When the weekly harvest finds a new paper on this topic, these counts change and the characterisation changes with them. That is the point: a hand-written claim about how strong an evidence base is starts decaying the day it is written.

Publication type is taken as the source records it. That is imperfect — journals label inconsistently, and a paper indexed as a "review" may be a systematic one — so treat the bands as approximate. They are accurate enough to distinguish a trial literature from a commentary literature, which is the distinction that matters.

The strongest work on this topic

Ordered by study design first, then recency. The full set is listed in the references below.

  1. Intermittent fasting for adults with overweight or obesity — Garegnani LI, Oltra G, Ivaldi D et al., 2026, meta-analysis
  2. Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: systematic review and network meta-analysis of randomised clinical trials — Semnani-Azad Z, Khan TA, Chiavaroli L et al., 2025, meta-analysis
  3. Therapeutic Fasting in Reducing Chemotherapy Side Effects in Cancer Patients: A Systematic Review and Meta-Analysis — Ferro Y, Maurotti S, Tarsitano MG et al., 2023, meta-analysis
  4. Intermittent fasting for the prevention of cardiovascular disease — Allaf M, Elghazaly H, Mohamed OG et al., 2021, systematic review
  5. Intermittent fasting versus continuous energy-restricted diet for patients with type 2 diabetes mellitus and metabolic syndrome for glycemic control: A systematic review and meta-analysis of randomized controlled trials — Wang X, Li Q, Liu Y et al., 2021, meta-analysis
  6. Intermittent fasting and weight loss: Systematic review — Welton S, Minty R, O'Driscoll T et al., 2020, systematic review
  7. Efficacy and Safety of Intermittent Fasting in People With Insulin-Treated Type 2 Diabetes (INTERFAST-2)-A Randomized Controlled Trial — Obermayer A, Tripolt NJ, Pferschy PN et al., 2023, randomised controlled trial
  8. Intermittent fasting plus early time-restricted eating versus calorie restriction and standard care in adults at risk of type 2 diabetes: a randomized controlled trial — Teong XT, Liu K, Vincent AD et al., 2023, randomised controlled trial
  9. Ketogenic Diet: A Nutritional Therapeutic Tool for Lipedema? — Verde L, Camajani E, Annunziata G et al., 2023, review
  10. Clinical application of intermittent fasting for weight loss: progress and future directions — Varady KA, Cienfuegos S, Ezpeleta M et al., 2022, review
How much research is there on fasting safety?
10 publications are indexed here, of which 2 are trials and 6 are syntheses.
Does more research mean a stronger conclusion?
No. Composition matters more than volume — five randomised trials support a claim far better than fifty commentaries, and citation counts do not distinguish between them.
How current is this?
The most recent paper indexed here is from 2026. The set is refreshed weekly from PubMed and Crossref.
Why does this page not tell me the answer?
Because summarising a literature into a conclusion requires reading it, and doing that automatically is how confident nonsense gets published. This page tells you how much weight a conclusion could bear; the articles on this site do the interpreting.

References

Every citation below links to the original peer-reviewed record on PubMed or via DOI. Nothing here is a substitute for medical advice.

  1. Intermittent fasting for adults with overweight or obesity Garegnani LI, Oltra G, Ivaldi D, et al. · The Cochrane database of systematic reviews · 2026 · Meta-analysis DOIPubMed 41692034Full text
  2. Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: systematic review and network meta-analysis of randomised clinical trials Semnani-Azad Z, Khan TA, Chiavaroli L, et al. · BMJ (Clinical research ed.) · 2025 · Meta-analysis DOIPubMed 40533200Full text
  3. Therapeutic Fasting in Reducing Chemotherapy Side Effects in Cancer Patients: A Systematic Review and Meta-Analysis Ferro Y, Maurotti S, Tarsitano MG, et al. · Nutrients · 2023 · Meta-analysis DOIPubMed 37375570Full text
  4. Intermittent fasting for the prevention of cardiovascular disease Allaf M, Elghazaly H, Mohamed OG, et al. · The Cochrane database of systematic reviews · 2021 · Systematic review DOIPubMed 33512717Full text
  5. Intermittent fasting versus continuous energy-restricted diet for patients with type 2 diabetes mellitus and metabolic syndrome for glycemic control: A systematic review and meta-analysis of randomized controlled trials Wang X, Li Q, Liu Y, et al. · Diabetes research and clinical practice · 2021 · Meta-analysis DOIPubMed 34391831
  6. Intermittent fasting and weight loss: Systematic review Welton S, Minty R, O'Driscoll T, et al. · Canadian family physician Medecin de famille canadien · 2020 · Systematic review PubMed 32060194Full text
  7. Intermittent fasting plus early time-restricted eating versus calorie restriction and standard care in adults at risk of type 2 diabetes: a randomized controlled trial Teong XT, Liu K, Vincent AD, et al. · Nature medicine · 2023 · Randomised controlled trial DOIPubMed 37024596
  8. Efficacy and Safety of Intermittent Fasting in People With Insulin-Treated Type 2 Diabetes (INTERFAST-2)-A Randomized Controlled Trial Obermayer A, Tripolt NJ, Pferschy PN, et al. · Diabetes care · 2023 · Randomised controlled trial DOIPubMed 36508320Full text
  9. Ketogenic Diet: A Nutritional Therapeutic Tool for Lipedema? Verde L, Camajani E, Annunziata G, et al. · Current obesity reports · 2023 · Review DOIPubMed 37924422Full text
  10. Clinical application of intermittent fasting for weight loss: progress and future directions Varady KA, Cienfuegos S, Ezpeleta M, et al. · Nature reviews. Endocrinology · 2022 · Review DOIPubMed 35194176