Fasting Evidence

Evidence map

Circadian: what the evidence base looks like

12 publications, 4 of them trials and 4 syntheses. This page describes the shape of that literature rather than summarising its conclusions.

Updated 4 min read 12 citations

What the evidence on circadian is made of Of 12 publications on this topic, the breakdown by study type: 4 meta-analysis, 4 randomised trial, 4 review. 444meta-analysis (4)randomised trial (4)review (4)
12 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 circadian literature was published Publication years for the 12 papers on this topic, grouped into bands from before 2015 through to 2023 onwards. 2023 onwards4 papers2020-20224 papers2015-20194 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. Food Intake According to Clock Gene Polymorphisms: A Systematic Review — Campos LT, Fonseca PF, Rocha DMUP et al., 2025, systematic review
  2. Changes in energy and macronutrient intakes during Ramadan fasting: a systematic review, meta-analysis, and meta-regression — Abdelrahim DN, El Herrag SE, Khaled MB et al., 2024, meta-analysis
  3. Daily Timing of Meals and Weight Loss After Bariatric Surgery: a Systematic Review — Cossec M, Atger F, Blanchard C et al., 2021, systematic review
  4. Timing of food intake: Sounding the alarm about metabolic impairments? A systematic review — Beccuti G, Monagheddu C, Evangelista A et al., 2017, systematic review
  5. Exploring circadian and meal timing impacts on cortisol during simulated night shifts — Grosser L, Yates C, Dorrian J et al., 2026, randomised controlled trial
  6. Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity — Vujović N, Piron MJ, Qian J et al., 2022, randomised controlled trial
  7. Prolonged, Controlled Daytime versus Delayed Eating Impacts Weight and Metabolism — Allison KC, Hopkins CM, Ruggieri M et al., 2021, randomised controlled trial
  8. Early Time-Restricted Feeding Improves 24-Hour Glucose Levels and Affects Markers of the Circadian Clock, Aging, and Autophagy in Humans — Jamshed H, Beyl RA, Della Manna DL et al., 2019, randomised controlled trial
  9. Chrononutrition and Energy Balance: How Meal Timing and Circadian Rhythms Shape Weight Regulation and Metabolic Health — Reytor-González C, Simancas-Racines D, Román-Galeano NM et al., 2025, review
  10. Circadian rhythms and meal timing: impact on energy balance and body weight — Boege HL, Bhatti MZ, St-Onge MP, 2021, review
How much research is there on circadian?
12 publications are indexed here, of which 4 are trials and 4 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. Food Intake According to Clock Gene Polymorphisms: A Systematic Review Campos LT, Fonseca PF, Rocha DMUP, et al. · FASEB journal : official publication of the Federation of American Societies for Experimental Biology · 2025 · Systematic review DOIPubMed 40787788Full text
  2. Changes in energy and macronutrient intakes during Ramadan fasting: a systematic review, meta-analysis, and meta-regression Abdelrahim DN, El Herrag SE, Khaled MB, et al. · Nutrition reviews · 2024 · Meta-analysis DOIPubMed 37986623
  3. Daily Timing of Meals and Weight Loss After Bariatric Surgery: a Systematic Review Cossec M, Atger F, Blanchard C, et al. · Obesity surgery · 2021 · Systematic review DOIPubMed 33604863
  4. Timing of food intake: Sounding the alarm about metabolic impairments? A systematic review Beccuti G, Monagheddu C, Evangelista A, et al. · Pharmacological research · 2017 · Systematic review DOIPubMed 28928073
  5. Exploring circadian and meal timing impacts on cortisol during simulated night shifts Grosser L, Yates C, Dorrian J, et al. · Sleep · 2026 · Randomised controlled trial DOIPubMed 40838738
  6. Late isocaloric eating increases hunger, decreases energy expenditure, and modifies metabolic pathways in adults with overweight and obesity Vujović N, Piron MJ, Qian J, et al. · Cell metabolism · 2022 · Randomised controlled trial DOIPubMed 36198293Full text
  7. Prolonged, Controlled Daytime versus Delayed Eating Impacts Weight and Metabolism Allison KC, Hopkins CM, Ruggieri M, et al. · Current biology : CB · 2021 · Randomised controlled trial DOIPubMed 33259790Full text
  8. Early Time-Restricted Feeding Improves 24-Hour Glucose Levels and Affects Markers of the Circadian Clock, Aging, and Autophagy in Humans Jamshed H, Beyl RA, Della Manna DL, et al. · Nutrients · 2019 · Randomised controlled trial DOIPubMed 31151228Full text
  9. Chrononutrition and Energy Balance: How Meal Timing and Circadian Rhythms Shape Weight Regulation and Metabolic Health Reytor-González C, Simancas-Racines D, Román-Galeano NM, et al. · Nutrients · 2025 · Review DOIPubMed 40647240Full text
  10. Circadian rhythms and meal timing: impact on energy balance and body weight Boege HL, Bhatti MZ, St-Onge MP · Current opinion in biotechnology · 2021 · Review DOIPubMed 32998085Full text
  11. Snacking in nutrition and health Marangoni F, Martini D, Scaglioni S, et al. · International journal of food sciences and nutrition · 2019 · Review DOIPubMed 30969153
  12. Circadian regulation of glucose, lipid, and energy metabolism in humans Poggiogalle E, Jamshed H, Peterson CM · Metabolism: clinical and experimental · 2018 · Review DOIPubMed 29195759Full text