Evidence summaries on fasting and metabolic health

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Cited guides to intermittent fasting, water-only fasting, and the fasting-mimicking diet.

FMD Research: What the Studies Actually Show

This page breaks down, trial by trial, what human and animal research on the fasting-mimicking diet has actually found, by population, study size, and outcome, including studies that found no benefit or a mixed result. It is a companion to our plain-language FMD overview, for readers who want to see the underlying studies themselves.

By the fasting.com team

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Medical caution

This is general information about fasting, not medical advice. Fasting can affect blood sugar, blood pressure, medication timing, and nutritional status. Talk to a clinician before starting or changing a fasting practice if you are pregnant, under 18, living with diabetes or another chronic condition, taking prescription medication, or have a history of an eating disorder.

This page is a companion to the fasting-mimicking diet overview: the overview explains what an FMD is and how it differs from water fasting and daily intermittent fasting; this page is the trial-by-trial breakdown for readers who want to see the underlying studies themselves, rather than a plain-language summary.

This page covers fasting-mimicking diet research in people without cancer or multiple sclerosis; trials of the diet alongside treatment for those conditions are a separate area and are not summarised here.

How to Read This Page

Each row in the tables below names the trial, who was studied, the design and duration, what the trial found, and what it did not find or could not show. Each row is also tagged supports, limited evidence, no effect found, or contradicts, the same scale used throughout this site's reference lists. Product names, suppliers, and personal funding ties are not repeated next to any result; they are gathered once, in full, in "Authors and Funding of the Cited Studies" below.

Trial-by-trial evidence
StudyPopulationDesignWhat it foundWhat it did not findFinding
van den Burg et al., 2024Type 2 diabetes, managed with metformin alone or diet aloneRCTn = 10012 monthsReduced need for glucose-lowering medication (adjusted treatment effect -0.3, 95% CI -0.4 to -0.2, p<0.001); HbA1c -3.2 mmol/mol (p=0.04); weight -3.6 kg (p<0.001)No data on insulin-treated or sulfonylurea-treated patients; 18 of 100 participants lost to follow-upsupports
Sulaj et al., 2022Type 2 diabetes with diabetic kidney disease (some participants on insulin or oral glucose-lowering drugs, dose-reduced or discontinued under supervision)RCTn = 406 months, 3-month follow-upHOMA-IR reduced (p<=0.05), sustained at follow-up; albuminuria reduced in the microalbuminuria subgroup only (p<=0.05)No significant overall difference in albuminuria, the primary outcome, versus a Mediterranean diet (p=0.45); no improvement in the macroalbuminuria subgrouplimited evidence
Tang and Lin, 2020Type 2 diabetesRCTn = 1004 monthsFasting glucose, HbA1c, lipids, blood pressure, and weight all improved more than control (all p<0.05)No head-to-head comparison against ordinary calorie restrictionsupports
van der Velden et al., 2024South-Asian Surinamese adults with type 2 diabetes (some on insulin or a sulfonylurea, dose-reduced under supervision; 2 low-blood-sugar episodes, 1 withdrawal)RCT, 3-armn = 563 months, 3-month follow-upTemporary improvement in BMI and HbA1cDid not preserve microvascular endothelial health, its primary outcome, with one measure worsening at follow-up; a glycocalyx-supplement comparison arm improved microvascular markers insteadcontradicts
Xiaoyu, Yuxin, and Li, 2024Type 2 diabetesNetwork meta-analysis, 13 RCTsn = 867Varies by pooled trialAll four fasting regimens tested, including FMD, improved glucose control versus a conventional diet; twice-weekly fasting ranked best on a composite scoreNo significant difference between FMD and the other three regimensno effect found
Wei et al., 2017Generally healthy adultsRCTn = 100Three monthly 5-day cyclesReduced weight, trunk and total body fat, blood pressure, and IGF-1; a post-hoc subgroup at higher disease risk improved more; no serious adverse effectsNo disease-prevention or treatment outcome measured; the authors state larger trials in diagnosed disease are still neededsupports
Brandhorst et al., 2015Generally healthy adults, a human pilot within a mouse and yeast paperPilot RCTn = 38Three 5-day cyclesDecreased biomarkers for aging, diabetes, cardiovascular disease, and cancer risk; no major adverse effects reportedNo disease-outcome or longevity data in the human portion, that evidence is mouse-only, see the animal research below; the authors call these preliminary results, 14% of enrolled participants withdrew for non-diet reasons and 5% were disqualified for non-compliancelimited evidence
Burns et al., 2025Generally healthy adultsRCT, low-protein vs high-protein FMD vs controln = 467 daysBoth FMD variants reduced weight and fat mass (P<0.0001), fasting glucose (about 10%), and IGF-1 (about 35%); the high-protein variant additionally improved visceral fat, triglycerides, heart-rate variability, and gut-microbiome diversityThe low-protein variant did not move visceral fat, triglycerides, heart-rate variability, or gut-microbiome diversitysupports
Sadeghian et al., 2021Women with obesity, metabolically healthyRCTn = 602 monthsMore favorable fat-mass and muscle-mass preservation; basal metabolic rate better preserved than with continuous calorie restrictionNo significant difference in weight loss versus continuous calorie restriction (CR -2.29 kg vs FMD -1.13 kg, p=0.06)contradicts
Videja et al., 2022Healthy volunteersRandomized, FMD vs a vegetable-intake comparison groupn = 435 daysA twofold decrease in plasma TMAO, which did not fall in the comparison group; lowered IGF-1 and HOMA-IR from baseline; 2.8 +/- 0.2 kg weight lossNo comparison against calorie restriction or a no-intervention controlsupports
Nardon et al., 2022Physically active young menRCTn = 24Three cyclesNo reduction in neuromuscular force production or muscle volume despite weight loss during the diet (-2.6 kg, P<0.05)Not tested in older adults, people with obesity, or anyone already at risk of muscle loss, which the authors say remains untested; the authors suggest FMD could be adopted by strength athletes, which this trial did not test directlyno effect found
Maloh et al., 2023Healthy women, aged 35 to 60RCTn = 4571 days, three monthly cyclesIncreased skin hydration (p=0.00013 at day 11); skin texture maintained over 71 days while roughness increased in the control group; self-reported happiness and confidence improvedNo comparison against another diet or calorie restrictionlimited evidence
Mishra, Fanti, et al., 2023Adults with overweight or obesity and hypertensionRCT, FMD vs Mediterranean dietn = 84 (44 FMD, 40 Mediterranean diet)4 months, 4 cyclesThe authors interpret a within-group decrease in one endothelial marker (reactive hyperemia index) as more likely reflecting vascular rejuvenation than impaired vascular function, citing the improved cardiometabolic profile seen alongside it; HbA1c and IGF-1 also decreased (p=0.0059, p=0.0427); both diets improved weight, BMI, waist circumference, fat mass, and cholesterol comparablyNo significant difference between FMD and the Mediterranean diet on any measure at the end of the intervention period; the Mediterranean-diet group, not the FMD group, lost lean mass at follow-uplimited evidence
Espinoza et al., 2026Healthy adults, mean age 49RCT, two FMD formulations vs usual dietn = 308 daysA significant difference between groups from baseline to day 6 in weight, fasting glucose, a ketone marker, HOMA-IR, and a blood autophagy marker (p<0.05 each)The authors state plainly that differences were not significant across all time pointslimited evidence
Khodadadi et al., 2024People with MASLD (fatty liver disease)RCTn = 10012 weeksReduced triglycerides, cholesterol, glucose, insulin, an inflammation marker, and liver enzymes across all arms; FMD plus flaxseed was not superior to either aloneThis trial's 'FMD' arm is defined as 16 hours of daily fasting, not the periodic 5-day low-calorie protocol every other row on this page means by the term; its results are not counted as evidence about that FMDlimited evidence
Mishra et al., 2021Female miceAnimal study, high-fat and high-calorie dietn = not applicable, mouse study2 yearsFMD cycles blocked most harmful effects of a high-fat diet: obesity, high blood sugar, high cholesterol, and impaired glucose and insulin tolerance; no lean-mass loss in the miceNo human data; this is 100% animal data and is never phrased as a human outcome on this sitelimited evidence
Brandhorst et al., 2015Mice and yeastAnimal and yeast studyn = not applicable, animal and yeast studyVaries by experimentExtended longevity, lowered visceral fat, reduced cancer incidence and skin lesions, immune rejuvenation, and improved cognitive performance in old miceNo human data for these specific findings; the same paper's small human pilot is reported separately above and is not blended with these mouse resultslimited evidence
Mohammadzadeh et al., 2025Pooled across 11 qualified studies (12 sub-studies)Systematic review and meta-analysisn = 761Varies by pooled trialSignificant reductions in HbA1c, IGF-1, systolic blood pressure, and diastolic blood pressureNo significant effect on the other cardiovascular risk factors checked; in the authors' sensitivity analyses, the IGF-1 reduction was no longer significant without either a trial in women receiving chemotherapy for breast cancer (not cited on this site) or Wei et al., 2017, and the blood-pressure reductions were no longer significant without Tang and Lin, 2020limited evidence
Tavakoli et al., 2025Pooled across 16 RCTs of fasting regimens generally (intermittent fasting, time-restricted eating, alternate-day fasting, and FMD, not isolated)GRADE-assessed systematic review and meta-analysisn = FMD not isolated from the other pooled regimensVaries by pooled trialDecreased leptin and ghrelinNo significant effect on resistin; only a marginal, non-significant increase in adiponectin; does not isolate FMD from the other pooled fasting regimenslimited evidence
Rahmani et al., 202219 human cohort studiesMeta-analysis, background mechanism, not an FMD trialn = 30876Varies by pooled cohortA U-shaped relationship between IGF-1 and all-cause mortality: both low and high IGF-1 carried higher mortality risk than a mid-range levelDoes not test FMD directly; lowering IGF-1 further is not automatically more favorable, given the U-shaped curvelimited evidence

What This Research Does Not Yet Show

  • No trial in this set followed participants for more than about 12 months, and most ran weeks to a few months; durability beyond a year is untested here.
  • Only one trial in this set tested FMD head-to-head against ordinary calorie restriction for weight loss, and found no significant difference (Sadeghian et al., 2021) [6]. A reader cannot conclude from this page that FMD beats simple calorie counting for weight loss.
  • No pediatric or pregnancy data exists in this set.

Authors and Funding of the Cited Studies

  • Wei et al., 2017 [1]: Valter D. Longo is senior and corresponding author. The paper's competing-interests statement: "The experimental FMD was provided by L-Nutra Inc." The University of Southern California has licensed intellectual property to L-Nutra, with potential royalty payments to the university. "V.D.L. and T.E.M., who have equity interest in L-Nutra, did not participate in the collection and analysis of the data. One-hundred percent of V.D.L.'s equity will be assigned to the nonprofit foundation Create Cures." U.S. patents related to the work have been filed.
  • Brandhorst et al., 2015 [2]: Longo is senior and corresponding author. From the paper: "VDL and TEM have equity interest in L-Nutra, a company that develops medical food. Neither author had any role in data analysis." The University of Southern California has licensed intellectual property to L-Nutra, with potential royalty payments to the university.
  • van den Burg et al., 2024 [3]: Longo is a co-author, not the senior author. Funding statement: the trial "was co-funded by Health~Holland, Top Sector Life Sciences & Health, the Dutch Diabetes Foundation and L-Nutra." The authors' relationships statement adds that Longo "is a founder and shareholder of L-Nutra (his shares are assigned to the Create Cures Foundation and other charitable and research organisations), owns patents licensed to L-Nutra, receives support for travel expenses from L-Nutra and is on the advisory board of L-Nutra."
  • Maloh et al., 2023 [4]: no Longo author. Several authors are identified as employees of L-Nutra, and the paper states L-Nutra supplied the study data. This research was funded by L-Nutra.
  • Burns et al., 2025 [5]: no Longo author. Trial registry (NCT06560996): lead sponsor University of Nottingham, collaborator Chenot Group, HC International SA; no apparent L-Nutra connection. The paper's competing-interest statement: "GCG and ADM are employees of HC International SA, Weggis, Switzerland, during the project. GF is an employee of labor team w ag, Goldach, Switzerland, during the project."
  • Sadeghian et al., 2021 [6]: no Longo author and no L-Nutra funding tie found.
  • Espinoza et al., 2026 [7]: no Longo author. Min Wei and William Hsu are listed with an L-Nutra, Inc. affiliation. Funding statement: "This work was supported by L-Nutra, Inc. L-Nutra, Inc. did not participate in the conduct of the study, data collection, or analysis." Competing interests: "The authors declare no competing interests."
  • Khodadadi et al., 2024 [8]: no Longo author and no L-Nutra funding tie found.
  • Nardon et al., 2022 [9]: Longo is a co-author, fourth of five authors; Bertucco is the corresponding author. This paper's own funding and competing-interest statement could not be retrieved for this page; the publisher's page returned an access block rather than article text.
  • Mishra et al., 2021 [10] (the mouse study): Longo is senior and corresponding author. Competing interests, from the paper: "V.D.L. has equity interest in L-Nutra, which develops and sells medical food... V.D.L. has committed all his equity in the company to charitable organizations."
  • Rahmani et al., 2022 [11]: Longo is senior and corresponding author. Conflict-of-interest statement, quoted verbatim: "AL and VDL have equity interest in a company producing medical food (L-Nutra). This is not directly but indirectly related to the topic of this meta-analysis." (AL is Alessandro Laviano, also a co-author on [1].)
  • Xiaoyu, Yuxin, and Li, 2024 [12]: no Longo author and no L-Nutra funding tie found.
  • Mohammadzadeh et al., 2025 [13]: no Longo author and no L-Nutra funding tie found.
  • Tavakoli et al., 2025 [14]: no Longo author and no L-Nutra funding tie found.
  • Sulaj et al., 2022 [15]: Longo is a co-author, not the senior author. Disclosure, from the paper: "L-Nutra, as funder of the fasting-mimicking diet used in this study, has no role in the design or conduct of the study... V.L. is founder and shareholder of L-Nutra; his shares are destined to the Create Cures Foundation and other charitable and research organizations."
  • Tang and Lin, 2020 [16]: no Longo author and no L-Nutra funding tie found; the paper states no conflict of interest.
  • Videja et al., 2022 [17]: no Longo author and no L-Nutra funding tie found; the paper states no conflict of interest.
  • van der Velden et al., 2024 [18]: no Longo author. "Fasting mimicking diet boxes (Prolon®) were provided by L-Nutra Inc." "Dietary supplement Endocalyx" was provided by MicroVascular Health Solutions LLC; co-author Vink is affiliated with MicroVascular Health Solutions LLC. "HV is Chief Science Officer at GlycoCheck BV." The trial was funded by consortium grant LSHM16058-SGF (GLYCOTREAT).
  • Mishra, Fanti, et al., 2023 [19] (a different trial from [10], same first author): Longo is senior and corresponding author. Competing interests, from the paper: "V.D.L. has equity interest in L-Nutra and owns the patents of the Fasting Mimicking Diet... The University of Southern California has licensed intellectual property to L-Nutra Inc. ... the University has the potential to receive royalty payments from L-Nutra Inc. For the present study, the experimental FMD was provided by L-Nutra Inc." A later Author Correction (2025, PMID 40987812) to this paper adds: "The clinical study was sponsored by L-Nutra Inc, which provided the experimental FMD and paid for all the associated procedures and lab tests"; "A grant was provided to the Hypertension Institute in Tennessee by L-Nutra"; and "V.D.L., S.B., and M.W. hold patents related to the Fasting Mimicking Diet but which are not a result of this trial."
  • Min Wei is an author on [1], [2], [10], [19], [4], and [7], with an L-Nutra, Inc. affiliation on the last two.
  • Stefano Brandhorst is an author on [1], [2], [10], and [19].

Safety and Cautions

This is general information, not medical advice, and carries the same standing cautions as the FMD overview: pregnancy, being under 18, and a history of an eating disorder are reasons to talk to a clinician first, none of which are directly studied in this set. Liver disease is not studied here either. Kidney disease was studied in one trial, in people with diabetic kidney disease, but only under clinical supervision throughout (Sulaj et al., 2022) [15]; that is not evidence that an FMD cycle is safe to try unsupervised with kidney disease, so route to a clinician either way. Anyone taking medication for diabetes or blood pressure should not attempt a multi-day, low-calorie FMD cycle without a clinician involved; two of the trials above required supervision and glucose monitoring for participants on insulin or other glucose-lowering drugs, and one recorded two low-blood-sugar episodes. None of these 19 citations support a cures, treats, or prevents framing for any disease.

References

  1. Wei M, Brandhorst S, Shelehchi M, Mirzaei H, Cheng CW, Budniak J, Groshen S, Mack WJ, Guen E, Di Biase S, Cohen P, Morgan TE, Dorff T, Hong K, Michalsen A, Laviano A, Longo VD (2017). Fasting-mimicking diet and markers/risk factors for aging, diabetes, cancer, and cardiovascular disease. Science Translational Medicine. PMID 28202779 doi:10.1126/scitranslmed.aai8700 Finding: supports
  2. Brandhorst S, Choi IY, Wei M, Cheng CW, Sedrakyan S, Navarrete G, Dubeau L, Yap LP, Park R, Vinciguerra M, Di Biase S, Mirzaei H, Mirisola MG, Childress P, Ji L, Groshen S, Penna F, Odetti P, Perin L, Conti PS, Ikeno Y, Kennedy BK, Cohen P, Morgan TE, Dorff TB, Longo VD (2015). A Periodic Diet that Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan. Cell Metabolism. PMID 26094889 doi:10.1016/j.cmet.2015.05.012 Finding: limited evidence
  3. van den Burg EL, Schoonakker MP, van Peet PG, van den Akker-van Marle EM, Lamb HJ, Longo VD, Numans ME, Pijl H (2024). Integration of a fasting-mimicking diet programme in primary care for type 2 diabetes reduces the need for medication and improves glycaemic control, a 12-month randomised controlled trial. Diabetologia. PMID 38546821 doi:10.1007/s00125-024-06137-0 Finding: supports
  4. Maloh J, Wei M, Hsu WC, Caputo S, Afzal N, Sivamani RK (2023). The Effects of a Fasting Mimicking Diet on Skin Hydration, Skin Texture, and Skin Assessment, a Randomized Controlled Trial. Journal of Clinical Medicine. PMID 36902498 doi:10.3390/jcm12051710 Finding: limited evidence
  5. Burns L, Cooper S, Sarmad S, Funke G, Di Mauro A, Gaitanos GC, Tsintzas K (2025). Effects of fasting-mimicking diets with low and high protein content on cardiometabolic health and autophagy, a randomized, parallel group study. Clinical Nutrition. PMID 40816210 doi:10.1016/j.clnu.2025.08.004 Finding: supports
  6. Sadeghian M, Hosseini SA, Zare Javid A, Ahmadi Angali K, Mashkournia A (2021). Effect of Fasting-Mimicking Diet or Continuous Energy Restriction on Weight Loss, Body Composition, and Appetite-Regulating Hormones Among Metabolically Healthy Women with Obesity. Obesity Surgery. PMID 33420673 doi:10.1007/s11695-020-05202-y Finding: contradicts
  7. Espinoza SE, Park S, Connolly G, Qi W, Zhang N, Semwal M, Li Y, Lauzon M, Salmon AB, Hsu W, Wei M, Musi N (2026). Effect of fasting-mimicking diet on markers of autophagy and metabolic health in human subjects. GeroScience. PMID 41372565 doi:10.1007/s11357-025-02035-4 Finding: limited evidence
  8. Khodadadi N, Sadeghi A, Poustchi H, Abbasi B, Nilghaz M, Melekoglu E, Yari Z, Hekmatdoost A (2024). Effectiveness of flaxseed consumption and fasting mimicking diet on anthropometric measures, biochemical parameters, and hepatic features in patients with Metabolic Dysfunction-Associated Steatotic Liver Disease (MASLD). Nutrition and Diabetes. PMID 39550356 doi:10.1038/s41387-024-00350-x Finding: limited evidence
  9. Nardon M, Venturelli M, Ruzzante F, Longo VD, Bertucco M (2022). Fasting-Mimicking-Diet does not reduce skeletal muscle function in healthy young adults: a randomized control trial. European Journal of Applied Physiology. PMID 35034194 doi:10.1007/s00421-021-04867-2 Finding: no effect found
  10. Mishra A, Mirzaei H, Guidi N, Vinciguerra M, Mouton A, Linardic M, Rappa F, Barone R, Navarrete G, Wei M, Brandhorst S, Di Biase S, Morgan TE, Ram Kumar S, Conti PS, Pellegrini M, Bernier M, de Cabo R, Longo VD (2021). Fasting-mimicking diet prevents high-fat diet effect on cardiometabolic risk and lifespan. Nature Metabolism. PMID 34650272 doi:10.1038/s42255-021-00469-6 Finding: limited evidence
  11. Rahmani J, Montesanto A, Giovannucci E, Zand H, Barati M, Kopchick JJ, Mirisola MG, Lagani V, Bawadi H, Vardavas R, Laviano A, Christensen K, Passarino G, Longo VD (2022). Association between IGF-1 levels ranges and all-cause mortality: A meta-analysis. Aging Cell. PMID 35048526 doi:10.1111/acel.13540 Finding: limited evidence
  12. Xiaoyu W, Yuxin X, Li L (2024). The effects of different intermittent fasting regimens in people with type 2 diabetes, a network meta-analysis. Frontiers in Nutrition. PMID 38332802 doi:10.3389/fnut.2024.1325894 Finding: no effect found
  13. Mohammadzadeh M, Amirpour M, Ahmadirad H, Abdi F, Khalesi S, Naghshi N, Bahrami A, Hejazi E (2025). Impact of Fasting Mimicking Diet (FMD) on cardiovascular risk factors: a systematic review and meta-analysis of randomized control trials. Diabetology and Metabolic Syndrome. PMID 40287774 doi:10.1186/s13098-025-01709-5 Finding: limited evidence
  14. Tavakoli A, Bideshki MV, Zamani P, Tavakoli F, Dehghan P, Gargari BP (2025). The effectiveness of fasting regimens on serum levels of some major weight regulating hormones, a GRADE-assessed systematic review and meta-analysis. Journal of Health, Population and Nutrition. PMID 40176106 doi:10.1186/s41043-025-00834-1 Finding: limited evidence
  15. Sulaj A, Kopf S, von Rauchhaupt E, Kliemank E, Brune M, Kender Z, Bartl H, Cortizo FG, Klepac K, Han Z, Kumar V, Longo V, Teleman A, Okun JG, Morgenstern J, Fleming T, Szendroedi J, Herzig S, Nawroth PP (2022). Six-Month Periodic Fasting in Patients With Type 2 Diabetes and Diabetic Nephropathy: A Proof-of-Concept Study. Journal of Clinical Endocrinology and Metabolism. PMID 35661214 doi:10.1210/clinem/dgac197 Finding: limited evidence
  16. Tang F, Lin X (2020). Effects of Fasting-Mimicking Diet and Specific Meal Replacement Foods on Blood Glucose Control in Patients with Type 2 Diabetes: A Randomized Controlled Trial. Oxidative Medicine and Cellular Longevity. PMID 33376581 doi:10.1155/2020/6615295 Finding: supports
  17. Videja M, Sevostjanovs E, Upmale-Engela S, Liepinsh E, Konrade I, Dambrova M (2022). Fasting-Mimicking Diet Reduces Trimethylamine N-Oxide Levels and Improves Serum Biochemical Parameters in Healthy Volunteers. Nutrients. PMID 35268068 doi:10.3390/nu14051093 Finding: supports
  18. van der Velden AIM, IJpelaar DHT, Chandie Shaw PK, Pijl H, Vink H, van der Vlag J, Rabelink TJ, van den Berg BM (2024). Role of dietary interventions on microvascular health in South-Asian Surinamese people with type 2 diabetes in the Netherlands: A randomized controlled trial. Nutrition and Diabetes. PMID 38600065 doi:10.1038/s41387-024-00275-5 Finding: contradicts
  19. Mishra A, Fanti M, Ge X, Vaughn D, Brandhorst S, Wei M, Hong KM, Pellegrini M, Pijl H, Houston MC, Longo VD (2023). Fasting mimicking diet cycles versus a Mediterranean diet and cardiometabolic risk in overweight and obese hypertensive subjects: a randomized clinical trial. npj Metabolic Health and Disease. PMID 40604264 doi:10.1038/s44324-023-00002-1 Finding: limited evidence