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Not medical advice. The Atlas is not a substitute for a clinician who can examine you.

Dry Fasting

Absolute Fast · No Food or Water

Evidence grade 1 of 5, Untested. Read how the Atlas grades evidence.

0 human trials, about 11 studies, ~Ramadan observational only. The written rationale for this grade is still being prepared.

FDA
Not recommended beyond 24h
WADA
Not prohibited

Reference only. Not medical advice.

What can go wrong

Risk rises sharply beyond roughly a day. Sustained water deprivation is associated with dehydration, electrolyte derangement, low blood pressure, and acute kidney injury that can progress to kidney failure; severe cases are associated with seizures, hypovolemic shock, heat injury, coma, and death, and rapid rehydration carries its own hazards. The promoted multi-day therapeutic benefits are not established in controlled human research. Dry fasting is especially hazardous for, and is not appropriate for, people who are pregnant or nursing, children and adolescents, older adults, anyone with kidney, cardiovascular, or metabolic disease, anyone on medication affecting fluids or electrolytes, and anyone with a current or past eating disorder or disordered eating. Religious day-fasts are a separate matter governed by each tradition, which themselves grant exemptions when health is at risk. Anyone considering fasting, and especially anyone in a higher-risk group, should consult a qualified medical provider first. Ēnel Health does not endorse multi-day dry fasting.

Dry fasting means complete abstention from both food and water. Short, roughly 24-hour dry fasts are observed safely within several religious traditions, and the largest related human evidence, observational Ramadan studies, has not shown clear kidney harm in monitored participants, though Ramadan permits water overnight and so does not test sustained dry fasting. The practice is heavily promoted in biohacking circles for multi-day durations on the basis of claims, dramatically accelerated autophagy and self-sustaining hydration from fat metabolism, that have no controlled human support. Metabolic water production is real biochemistry but far too small to offset multi-day water loss. Beyond about a day, the documented risks are serious: dehydration, electrolyte derangement, acute kidney injury, and in severe cases seizures, shock, and death. Ēnel Health documents this protocol for completeness and does not endorse multi-day dry fasting.

No food and no water. Heavily promoted, poorly evidenced, and genuinely risky beyond a day.

What people take it for

These are the reasons people give for taking it. They are not effects it has been shown to have.

  • Religious observance of bounded duration (e.g., ~25-hour Yom Kippur, daytime Ramadan, Hindu Nirjala Ekadashi), practiced within faith traditions and outside any Ēnel wellness claim
  • Claimed (and unproven) accelerated autophagy, attributed to advocates, not asserted by Ēnel
  • Claimed (and unproven) deep-tissue 'cleansing,' attributed to advocates, not asserted by Ēnel

What people get wrong

  • Often saidA day of dry fasting triggers two to three times more autophagy than water fasting, or equals three days of water fasting

    ActuallyThis figure is not from any controlled human study. It traces to a single rodent study (Ye et al., 2016) measuring an indirect autophagy marker (LC3-II) in rat and mouse brain tissue, re-interpreted on a commercial dry-fasting site. Dehydration stress as an autophagy accelerator in humans is hypothetical and untested. Human autophagy research, building on Yoshinori Ohsumi's Nobel-recognized work, relies on indirect markers and does not validate dry-specific multiples.

  • Often saidThe body makes enough water from burning fat to stay hydrated without drinking

    ActuallyMetabolic water is real: oxidizing fat yields roughly 1.07 to 1.1 g of water per gram of fat, more than carbohydrate (~0.6 g) or protein (~0.4 g) per Mellanby (1942) and the National Academies (2005). But it supplies only about 8 to 10 percent of daily water needs and cannot offset the liters lost each day through urine, breath, and skin. It does not make a multi-day dry fast self-sustaining or safe.

  • Often saidRamadan studies prove dry fasting is safe for the kidneys

    ActuallyRamadan permits drinking water (and eating) after sunset, so it is not a sustained dry fast. A 2024 meta-analysis of 32 observational Ramadan studies found no significant serum-creatinine or eGFR change, but the authors caution the studies are low quality with no evidence-based guidelines, and these findings cannot be extended to continuous multi-day water deprivation.

  • Often saidDry fasting is endorsed by Russia's health ministry, so it is medically validated

    ActuallyAccounts aligned with Sergei Filonov report that a 2005 Russian Ministry of Health document listed therapeutic dry fasting but capped it at 3 days. Even on its own terms that is a tight limit, not validation of the 9-to-11-day fasts Filonov himself promotes, and it is not reflected in mainstream international clinical guidance.

Who profits, and who pushes back

  • Julia Zumpano, RD

    Pushes backRegistered dietitian, Cleveland Clinic

    There's just not a lot of data on it. The risk of dry fasting is not worth the benefits, and those benefits aren't clinically proven.

  • Nephrology and hydration clinicians

    Pushes backAcute-risk clinical consensus (Cleveland Clinic, WebMD, Healthline expert reviews)

    Prolonged water deprivation is associated with dehydration, electrolyte imbalance, and acute kidney injury that can progress to kidney failure, with severe cases risking seizures, shock, and death; the touted benefits are not established.

  • Autophagy researchers

    Pushes backCell-biology scrutiny of fasting claims

    Human autophagy is assessed through indirect markers, and no controlled human study shows that removing water multiplies autophagy; dehydration as an autophagy accelerator in people is hypothetical, not demonstrated.

  • Dr. Sergei Filonov

    Sells this. Has a commercial interest in a product sold as this compound, as of July 2026.

    Promotes itRussia

    Promotes multi-day dry-fasting protocols; commercial and clinic interest. Claims far exceed the evidence.

  • Biohacking fringe

    Promotes itTelegram, alt-health

    Promotes extended dry fasting on unsupported mechanistic claims.

Where the research comes from

Most of the published research on this comes from one place. 60% of it is from Other. Findings that no unrelated group has reproduced are weaker than the study count makes them look.

Share of published research by country of origin.
PlaceShare of published research
Other60%
Russia40%

Research published from: Russia, Global biohacking.

How we got here

Short dry fasts have deep and global religious roots, predating any wellness framing. In Jewish practice the Yom Kippur fast runs about 25 hours and forbids water as well as food. In Hindu tradition, Nirjala Ekadashi (its Sanskrit name meaning 'without water') is an austere waterless day-fast tied to Vishnu and observed in the heat of the Indian summer; Ekadashi observance is also honored in Jainism. The Islamic fast of Ramadan abstains from food and water during daylight for a lunar month, with intake resumed after sunset. Across these traditions the duration is bounded to a day or to daylight hours, durations the body generally tolerates. The modern multi-day dry-fasting movement is a separate, contemporary phenomenon, promoted most prominently by the Russian physician Sergei Filonov, who reports extending fasts to 11 days in his Altai clinic, and amplified through biohacking channels on dramatic but unsubstantiated claims. Ēnel records both strands while keeping them firmly distinct.

  1. AntiquityWaterless religious day-fasts established: the ~25-hour Yom Kippur fast forbids food and water
  2. AntiquityHindu Nirjala Ekadashi, the 'without water' fast, observed as the most austere of the year's Ekadashis; honored in Jainism as well
  3. 7th centuryRamadan codified in Islam as a lunar month of daytime abstention from food and water, with intake after sunset
  4. 1942Mellanby quantifies metabolic water yields in Nature, the physiology later invoked, and misused, by dry-fasting advocates
  5. 2005Russian Ministry of Health guidelines reportedly list therapeutic dry fasting but limit it to 3 days (per Filonov-aligned accounts)
  6. 2008-2015Filonov publishes books promoting multi-day, including fractionated 9-to-11-day, dry fasting
  7. 2016Ye et al. publish rodent aquaporin/autophagy work later cited by advocacy sites as the basis for 'accelerated autophagy' claims
  8. 2010s-2020sBiohacking channels and dry-fasting clubs amplify unsupported multi-day claims online
  9. 2024Systematic review/meta-analysis of 32 Ramadan observational studies finds no clear kidney-function deterioration but flags low study quality and absent guidelines

At a glance

Definition
No food OR water
Religious form
24h (Yom Kippur, etc.)
Claimed
"Accelerated autophagy"
Evidence
Essentially none

What this entry does not yet cover

What follows is unfinished work on our side, not a finding about Dry Fasting. A short entry is not a safe entry.

  • Cost and market. We have not documented what it sells for or who sells it.
  • Supply chain. We have not mapped where it is made.
  • Who uses it. We have not documented the user groups.
  • What could change. No forward-looking summary yet.
  • How it compares. We have not set it against the alternatives.
  • Children and teenagers. We have not checked what is known about younger people.

Sources