how often should you do a 72 hour fast
You’ll see a lot of different opinions online, but most recent expert-style guidance lands around this: for a generally healthy adult, a 72‑hour water fast should be rare, not routine—think no more than once a month , and for many people just a few times per year, ideally with medical guidance. Anything more frequent starts to meaningfully raise the risk of nutrient deficiencies, muscle loss, and other complications, especially if your day‑to‑day diet and health status aren’t dialed in.
Quick Scoop
- 72‑hour fasts are considered an extended or prolonged fast, not a routine weight‑loss tool.
- Common conservative advice:
- “A few times per year” for otherwise healthy people who are already used to shorter fasts.
* “No more than once monthly” for most healthy adults, and often less.
- There are no strong, evidence‑based guidelines that say you should do recurring 72‑hour fasts at all.
- Many reputable sources recommend focusing on 14–16 hour daily fasting or occasional 24‑hour fasts instead, using 72‑hour fasts only sparingly.
- Always talk with a doctor first if you have any medical conditions, take medications, are pregnant/breastfeeding, or have any history of disordered eating.
What current articles and forums suggest
Recent health and fitness blogs, as well as keto/fasting resources, emphasize caution with 72‑hour fasts and frame them as an occasional “deep reset” rather than a regular habit.
Some typical patterns you’ll see:
- “A few times per year”
- Fitness‑focused and longevity‑focused writers often say a 3‑day fast might be used a few times annually, as a bigger metabolic “reboot.”
- “No more than once a month”
- Some practical guides suggest that, for most healthy adults, monthly is an upper limit that tries to balance potential benefits with safety.
- Forum chatter
- People on fasting forums sometimes report doing 72‑hour fasts once every week or two, but even community members often caution that this is aggressive and not necessary for most people.
Meanwhile, larger wellness and weight‑management platforms stress that there are no official medical guidelines that endorse regular 72‑hour fasts, and they note that repeating long fasts can raise the risk of muscle loss and nutrient gaps without professional oversight.
Why “less often” is safer
Extended water fasts push your body into deep energy conservation mode and can affect hormones, blood pressure, and electrolytes. Doing them often makes it harder to maintain:
- Adequate protein and micronutrients , which you must cram into fewer eating days.
- Muscle mass , which can be lost if long fasts stack up without enough refeeding and resistance training.
- Stable energy and mood , since 3 days without calories is physiologically stressful for many people.
Most mainstream and coaching‑type sources now suggest building a base with shorter approaches —like 14:10, 16:8, or occasional 24‑hour fasts—and only experimenting with 72‑hour fasts after that, and even then, rarely.
A simple “if you’re determined to try it” framework
If you and your healthcare provider have already decided a 72‑hour fast might be reasonable for you, common practical patterns look like:
- Start with shorter fasting
- Use daily time‑restricted eating (14–16 hours) or occasional 24‑hour fasts for weeks or months first.
- Treat 72‑hour fasts as special events, not habits
- For many healthy adults: 1–4 times per year is a conservative “special event” zone.
* If you go as high as **monthly** , that’s already at the upper “aggressive” end of what many guides consider acceptable for otherwise healthy people.
- Prioritize safety
- Stay on top of hydration and electrolytes, pause heavy training, and break the fast gradually to avoid GI upset or more serious refeeding issues.
* Stop early and seek medical help if you feel faint, confused, or very unwell.
Multi‑view: how often should you do a 72 hour fast?
Here’s how different “camps” tend to look at it based on current online articles and guides.
| Perspective | How often they suggest | Core reasoning |
|---|---|---|
| Conservative medical- style view | No routine 72-hour fasts; if done, under medical supervision only. | [9][7]Limited human data, risk of nutrient deficits, blood pressure drops, and muscle loss. | [7][9]
| Moderate wellness/fitness view | A few times per year, sometimes up to once a month for healthy, experienced fasters. | [10][3][5][7]Use 3-day fasts as periodic “deep resets,” not weekly tools; rely on shorter fasts for ongoing benefits. | [5][9][7]
| Aggressive fasting- enthusiast view (forums) | Sometimes weekly or every other week, though even peers often warn this is extreme. | [1]Chasing rapid fat loss or autophagy, but often with less emphasis on long-term safety. | [1]
Story‑style example
Imagine someone who has been doing 16:8 fasting for a year, feels good, and gets regular check‑ups. They discuss a 72‑hour fast with their doctor, plan it around a quiet weekend, and treat it like a big hike: preparation, respect, and recovery. They might do one successful 72‑hour fast in the spring, another in late summer, and decide that twice a year is enough because the recovery feels significant and their lab work and strength are priorities. Between those “big” fasts, they rely on their daily time‑restricted eating plus occasional 24‑hour fasts for ongoing benefits, instead of stacking multiple 72‑hour fasts every month. That pattern lines up fairly well with today’s cautious, science‑influenced advice: use 72‑hour fasts sparingly, only if you’re a good candidate, and never as a casual weekly habit.
Bottom line: There’s no proof you need recurring 72‑hour fasts, and many people are better off never doing them. If you do, “a few times per year” up to “about once a month at most” (for healthy, well‑screened individuals) is roughly where current practical guidance clusters—always in partnership with a qualified healthcare professional.
TL;DR: How often should you do a 72‑hour fast? For most healthy people who are already experienced with shorter fasting, think rare and deliberate: at most about once a month, and often only a few times per year, with medical input and careful prep and refeeding.
Information gathered from public forums or data available on the internet and portrayed here.