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Fasting-Mimicking Diet and Women: The Evidence

No human trial has been designed specifically to test whether the fasting-mimicking diet works differently for women than for men. What exists instead is a patchwork of secondary observations inside trials built to answer other questions: in one trial, 82% of the participants who dropped out during the diet cycles were women, in a study population that was about 63% female, for reasons its own authors call unexplained, and another found, in a post hoc analysis, that sex did not predict who responded to treatment. No trial has studied this diet in people who were pregnant or breastfeeding.

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 and the FMD research page. All of the trials below are already cited on those two pages for other outcomes; this page gathers what each one reports, or does not report, about sex, a question neither page organizes as its own topic. For the comparable evidence gap in daily intermittent fasting, see intermittent fasting for women, a different protocol with its own, separately reviewed evidence.

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 summarized here.

Do Women and Men Respond Differently to an FMD Cycle?

The clearest direct test of sex as a predictor of response is a post hoc analysis in a 12-month trial that randomized 100 people with type 2 diabetes managed with metformin alone or diet alone and analyzed 92 (49 on FMD: 53% male, 47% female; 43 on usual care: 51% male, 49% female). Sex failed to predict treatment response, for either treatment success or treatment failure. The authors concluded the FMD programme "emerges as a potential treatment option suitable for individuals of both sexes," while adding that "future studies should be specifically designed to identify if sex or other determinants can predict success" (van den Burg et al., 2024) [2].

This is a genuine, reassuring null finding, stated as what it is: one post hoc analysis in one trial, with 92 people analyzed. It does not establish that sex never matters to how FMD works, only that this particular trial did not find that it did.

One other trial reports a sex comparison. A 6-month trial in 40 people with type 2 diabetes and diabetic kidney disease, 71% of the FMD group and 74% of the Mediterranean-diet comparison group men, adjusted its analyses for age, sex, and weight loss and states that "no differences in primary or secondary endpoints were found between female and male participants (data not shown)" (Sulaj et al., 2022) [8]. That is a second null, but a weaker one: the comparison is reported in a sentence, with no figures published behind it, in a trial with 11 women in total.

Why Did More Women Drop Out of the First Major FMD Trial?

In the first large human trial of FMD, 100 generally healthy adults were randomized to three monthly 5-day cycles or their usual diet; the two study arms were already majority-female at enrollment (62.5% and 63.5% female). Ninety-five participants started the FMD (the 52 randomized to it plus 43 control participants who crossed over to it after 3 months). Compared with the 71 who completed all three cycles, the 24 who dropped out during the cycles did not differ in age or BMI, but 82% of them were women and 18% men (P = 0.0045, Fisher's exact test), in a study population that was about 63% female at enrollment.

The paper states plainly: "It remains to be established why we experienced a gender difference (82% of dropouts were female)" (Wei et al., 2017) [1]. This page does not add an explanation the trial's own authors did not give. It is the most statistically clear sex-related observation in this evidence base, and it is an open question, not a resolved one.

What the Other Trials Show About Sex, and What They Don't

A trial comparing FMD against a Mediterranean diet in adults with overweight or obesity and hypertension ended up, despite randomization, with significantly different sex composition between its two arms: 32 women and 12 men in the FMD arm (n=44) against 20 women and 20 men in the Mediterranean-diet arm (n=40), P = 0.0434. The trial's own authors list this alongside other baseline differences, such as age and body-fat percentage, as something "which could confound the interpretation of the results," and say they used a mixed-effects model with group as a fixed effect to account for the baseline differences (Mishra, Fanti, et al., 2023) [3]. This is a methodological caution specific to that trial's comparison, not a finding about how FMD affects women compared with men.

The human pilot behind the original mouse-and-yeast FMD study allocated participants to its two groups using "stratified sampling for age and gender": the control group was 9 women (47.4%) and 10 men (52.6%), the FMD group 7 women (36.8%) and 12 men (63.2%). No outcome in that paper is reported broken down by sex. Sex was accounted for at allocation, but it was never analyzed as a result (Brandhorst et al., 2015) [4].

In the remaining mixed-sex trials, sex appears only in the methods or the baseline table. The 6-month diabetic-kidney-disease trial adjusted for sex and reports its no-difference sentence without data, as described above (Sulaj et al., 2022) [8]. A 12-week trial in people with fatty liver disease stratified its randomization by sex and age and reports its participants as 46% women, with no sex-stratified outcome; its "FMD" arm was 16 hours of daily fasting, a different intervention from the multi-day protocol every other trial on this page tested, as the overview page notes (Khodadadi et al., 2024) [10]. A 5-day trial in 43 healthy volunteers reports sex only in its baseline table (13 of 19 women in the vegetable-diet group, 15 of 24 in the FMD group) and randomized by fasting glucose, with no sex-adjusted or sex-stratified result (Videja et al., 2022) [9]. A 4-month trial in 100 people with type 2 diabetes enrolled "adult male and female participants" and reports no sex breakdown at all (Tang and Lin, 2020) [7]. A separate 8-day pilot's population was 83.3% female (25 of 30 participants), a composition consistent across its three sub-arms (72.7% to 90.0%, P = 0.58 for the baseline difference between arms), with no sex-stratified result reported (Espinoza et al., 2026) [11].

No PMC full text is available for a 7-day trial of a low-protein and a high-protein FMD variant in 46 generally healthy adults; its abstract describes the population only as "healthy men and women," with no sex count given; we could not check the full text for a sex-stratified result (Burns et al., 2025) [13].

Across these trials, sex was recorded and sometimes balanced for at randomization; one reports a sex comparison with no data shown, and none analyzed sex as its own question with published results.

The Two Trials Conducted Only in Women

Two trials in this evidence base studied FMD in women exclusively, and neither was designed to compare women against men.

A 2-month trial in 60 women with obesity, metabolically healthy, found no significant difference in weight loss between FMD and ordinary calorie restriction (calorie restriction -2.29 kg versus FMD -1.13 kg, P = 0.06), with more favorable fat-mass and muscle-mass preservation on FMD (Sadeghian et al., 2021) [12]. See the FMD research page for this trial's full treatment; it is not re-explained here.

A 71-day trial in 45 healthy women aged 35 to 60 tested FMD's effect on skin hydration and texture; the age range spans typical perimenopausal years, but the paper reports no menopausal-status breakdown or stratification (Maloh et al., 2023) [6]. That is a gap worth naming, not an assumption in either direction. See the FMD research page for this trial's full treatment.

Pregnancy, Breastfeeding, and What Has Never Been Studied

No trial in this evidence base studied FMD in a pregnant or breastfeeding participant. Pregnancy is a stated exclusion criterion in eight of the thirteen trials on this page, and breastfeeding, nursing, or lactation in six of them: Wei et al., 2017 [1] excludes "pregnant or nursing female[s]"; Brandhorst et al., 2015 [4] uses the same exclusion language; Maloh et al., 2023 [6] excludes "breastfeeding, pregnancy or planned pregnancy during the study"; Tang and Lin, 2020 [7] excludes "pregnant and lactating women"; Mishra, Fanti, et al., 2023 [3] excludes "pregnancy, lactating"; Khodadadi et al., 2024 [10] excludes "pregnant or breastfeeding women"; van den Burg et al., 2024 [2] and Espinoza et al., 2026 [11] list pregnancy among their exclusions. The remaining trials state neither in the text available to us (Sulaj et al., 2022 [8]; Videja et al., 2022 [9]; Sadeghian et al., 2021 [12]; Burns et al., 2025 [13]), and none reports enrolling a pregnant or breastfeeding participant. This is a tested-and-excluded population, not a tested-and-found-safe one.

One real pregnancy event occurred in this evidence base: in a trial in people with type 2 diabetes, "one patient withdrew due to pregnancy at the start of the study" in the FMD group (van der Velden et al., 2024) [5]. The participant withdrew before the intervention began. This is not evidence about FMD during pregnancy; it is a real-world example of a trial protocol responding to pregnancy with withdrawal, consistent with the pregnancy exclusions stated in the trials above.

Where the Real Sex-Specific Research Is, and Why It Is Not Here

The largest women-only FMD trial we found is a trial in women receiving chemotherapy for breast cancer, randomized to FMD or their regular diet alongside that treatment. It is not cited on this site, because 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 summarized here. That is the context for the thin sex-specific FMD evidence outside oncology: the largest women-only FMD trial we found is a cancer trial, not a general-population one.

Who Should Not Try an FMD Without a Clinician

Nothing on this page changes who should talk to a clinician before trying an FMD; the trials above are secondary observations about sex within trials built to answer other questions, not a reason to loosen or tighten that list. See the overview's Who Should Not Try an FMD Without a Clinician section for the complete, already-reviewed list, including pregnancy, breastfeeding, a history of an eating disorder, and diabetes medication.

Safety and Cautions

This is general information, not medical advice. Talk to a clinician before trying an FMD if you are pregnant, breastfeeding, trying to conceive, under 18, have a history of an eating disorder, or manage diabetes or blood pressure with medication. Pregnancy, breastfeeding, trying to conceive, being under 18, and a history of an eating disorder were not studied in any trial on this page. People managing type 2 diabetes or blood pressure with medication were studied in several of them, but only under clinical supervision, with glucose-lowering medication adjusted by protocol during each cycle; that is not evidence about trying a cycle without that supervision. See the FMD overview for the full list of who should talk to a clinician first.

Authors and Funding of the Cited Studies

  • Wei et al., 2017 [1]: Longo is senior and corresponding author. "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; Longo's equity is committed to the Create Cures Foundation.
  • van den Burg et al., 2024 [2]: Longo is a co-author, not the senior author. Co-funded by Health~Holland, Top Sector Life Sciences & Health, the Dutch Diabetes Foundation, and L-Nutra; the paper's funding section adds that "L-Nutra contributed the formula diet and a small part of the funding" and that the funders "had no role in study design, data collection, data analysis, data interpretation, writing of the report, approval of the manuscript or the decision to submit the manuscript for publication." Longo discloses founder and shareholder status in L-Nutra (shares assigned to the Create Cures Foundation and other charitable and research organisations), patents licensed to L-Nutra, travel support from L-Nutra, and a seat on L-Nutra's advisory board.
  • Mishra, Fanti, et al., 2023 [3]: Longo is senior and corresponding author. Competing interests, from the paper as corrected (Author Correction, 2025, PMID 40987812): "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"; "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. As part of this license agreement, the University has the potential to receive royalty payments from L-Nutra Inc." The paper also states that L-Nutra "had no involvement in the study design, collection, analysis, and interpretation of data, writing of the report, manuscript revision or decision to submit the article for publication."
  • Brandhorst et al., 2015 [4]: Longo is senior and corresponding author. "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.
  • van der Velden et al., 2024 [5]: no Longo author. "Fasting mimicking diet boxes (Prolon®) were provided by L-Nutra Inc." A dietary supplement used in a comparison arm was provided by MicroVascular Health Solutions LLC; co-author Hans Vink (HV) lists MicroVascular Health Solutions LLC as an affiliation, and the paper's competing-interests statement reads: "HV is Chief Science Officer at GlycoCheck BV (Maastricht, the Netherlands). Other authors have nothing to disclose." The trial was funded by consortium grant LSHM16058-SGF (GLYCOTREAT).
  • Maloh et al., 2023 [6]: no Longo author. Several authors are identified as employees of L-Nutra, and the paper states L-Nutra supplied the study data and funded the research.
  • Tang and Lin, 2020 [7]: no Longo author and no L-Nutra funding tie found; the paper states no conflict of interest.
  • Sulaj et al., 2022 [8]: Longo is a co-author, not the senior author. "L-Nutra, as funder of the fasting-mimicking diet used in this study, has no role in the design or conduct of the study"; Longo discloses founder and shareholder status in L-Nutra.
  • Videja et al., 2022 [9]: no Longo author and no L-Nutra funding tie found; the paper states no conflict of interest.
  • Khodadadi et al., 2024 [10]: no Longo author and no L-Nutra funding tie found.
  • Espinoza et al., 2026 [11]: no Longo author. Min Wei and William Hsu are listed with an L-Nutra, Inc. affiliation. "This work was supported by L-Nutra, Inc. L-Nutra, Inc. did not participate in the conduct of the study, data collection, or analysis." The authors declare no competing interests.
  • Sadeghian et al., 2021 [12]: no Longo author and no L-Nutra funding tie found.
  • Burns et al., 2025 [13]: 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."
  • Disclosures are listed where the full text of the paper was available to us; a study not listed here is not a statement that its authors have no ties.

What the evidence actually supports

No trial has been designed to test whether the fasting-mimicking diet works differently for women than for men. What exists is secondary: one trial found a large, statistically significant sex skew in who dropped out (82% of dropouts were women versus 18% men, P = 0.0045), unexplained by age or BMI (Wei et al., 2017) [1]. A separate trial's post hoc analysis, in a 12-month trial that randomized 100 people with type 2 diabetes and analyzed 92, found sex did not predict treatment response (van den Burg et al., 2024) [2]; a third trial, in 40 people with type 2 diabetes and diabetic kidney disease, states that no differences between women and men were found in its outcomes, with the data not shown (Sulaj et al., 2022) [8].

A fourth trial's two comparison arms ended up significantly different in sex composition (32 women and 12 men on FMD versus 20 women and 20 men on a Mediterranean diet, P = 0.0434), which the trial's own authors flag as a possible confounder of that trial's results, a caution about that trial's comparison, not a finding about sex and FMD generally (Mishra, Fanti, et al., 2023) [3]. A human pilot trial allocated participants by age and sex (9 of 19 controls and 7 of 19 FMD participants were women) but never analyzed an outcome by sex (Brandhorst et al., 2015) [4].

In the other mixed-sex trials, sex appears only in the methods or the baseline table: one adjusted its analyses for sex and reports, without showing the data, no difference between women and men in its outcomes (Sulaj et al., 2022 [8]); one stratified its randomization by sex and age and reports no sex-stratified outcome (Khodadadi et al., 2024 [10]), and its "FMD" arm was 16 hours of daily fasting rather than the multi-day protocol the other trials tested; one reports sex only as a baseline characteristic (Videja et al., 2022 [9]); and one reports no sex breakdown at all (Tang and Lin, 2020 [7]). A further trial's population was 83.3% female, consistent across its three sub-arms, with no sex-stratified result reported (Espinoza et al., 2026) [11].

Two trials have studied FMD in women exclusively (Sadeghian et al., 2021 [12]; Maloh et al., 2023 [6]); neither was designed to compare women against men.

No trial has studied FMD in a pregnant or breastfeeding participant: eight of the thirteen trials state a pregnancy exclusion and six of those also exclude breastfeeding, the rest state neither in the text available to us, and the one pregnancy recorded in a trial led to withdrawal before the diet began (van der Velden et al., 2024) [5], not evidence about doing FMD while pregnant.

The largest women-only FMD trial we found enrolled women receiving chemotherapy for breast cancer and is outside this page's scope because it tests FMD alongside cancer treatment, not FMD on its own; it is not cited on this site.

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. 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
  3. 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
  4. 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
  5. 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
  6. 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
  7. 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
  8. 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
  9. 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
  10. 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
  11. 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
  12. 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
  13. 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