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Opinions on water fasting while on GLPs?

12 replies13 peopleJul 31, 2026☆ Follow
Summary

Is multi-day water fasting safe or beneficial while taking GLP-1 medications like retatrutide?

Users report mixed but mostly positive experiences with 3-5 day water fasts on these meds, noting preserved mental clarity and reduced hunger compared to pre-medication attempts. Hydration and electrolytes remain essential, while refeeding can feel more uncomfortable due to slowed gastric emptying. Several people mention concerns about low blood sugar as a potential risk, especially for those already prone to it.

What this discussion establishesWhere people disagree

Whether the practice adds meaningful value beyond what the medication already provides, or if it risks becoming unnecessary or unsafe.

Still open

How low blood sugar might actually become during multi-day fasts for most users on these drugs.

Nothing here is advice.

12 replies · 13 people
PatientAlder45archiveopening postJul 31

The question is about views and any personal stories regarding water-only fasts lasting several days up to a week while taking medications such as retatrutide. Clarifying it's not just skipping meals occasionally but full multi-day fasts with only water and zero-calorie electrolytes. Wondering if this brings advantages or if it's mostly unfounded.

PlainAnchor67archiveJul 31

Saw another discussion on fasting and whether anyone has tried it while using these medications. I used to fast years back and appreciated the mental clarity it gave. Planning to attempt it again soon but will need to watch how I break the fast because of slower digestion.

SteadyAnchor13archiveJul 31

Completed a three-day fast recently, the first time doing so while on these medications though I had done them regularly before. Staying hydrated proved tougher yet hunger did not distract me as much, leading to good mental clarity and a few pounds lost. The overall feeling matched earlier fasts, and I plan to repeat for autoimmune or allergy flare-ups. The main difference was that breaking the fast felt more uncomfortable even with a small normal meal.

PatientTimber39archiveJul 31
↳ replying to @PatientAlder45 (opening post)

Fasting appears worthwhile with solid supporting research on calorie restriction. Combining it with these medications has worked well for me, including stretches of three days on water only. I prepare my own electrolyte powder in bulk and add it to water throughout the day.

WryHarbour70archiveJul 31
↳ replying to @PatientAlder45 (opening post)

Some evidence supports occasional fasting for organ benefits such as liver recovery, since it allows a period without constant processing demands. Plenty of people strongly endorse the approach.

RustSparrow51archiveAug 1

I typically include a 3-to-5-day water fast once a month alongside keto and intermittent fasting habits. These longer fasts provide genuine advantages. I add salt to fluids and break the fast with bone broth. I skipped them recently while off cycle for a procedure and have not resumed yet because my intake is already lower.

AmberSignal47archiveAug 1

My overnight glucose reading after roughly 14 hours reached 55 mg/dl during a blood draw. That makes me hesitant to attempt anything longer.

CopperPebble12archiveAug 2

Fasting produces measurable body changes, yet adding several days of water-only intake to a strong medication like this can complicate maintaining proper nutrition.

QuietBramble77archiveAug 10

Considering a fast while on the medication for a while now. I can still consume a fair amount and used to do alternate-day style fasts a couple times a year before starting. Mainly want a reset after recent weight gain but worry about glucose levels dropping too far.

PatientFenwick55archiveAug 14

That approach sounds risky. My glucose already tends to run low even with regular eating, and earlier 24-to-36-hour fasts before these medications left me with headaches and fatigue that were not worth it.

RustMarble36archiveAug 14

If appetite is absent I sometimes go an entire day without eating without issue, often following one-meal patterns anyway. Low blood sugar has not been a problem for me, partly because activity stays low during the week. As weight comes down further, simple calorie cuts no longer suffice so I have been testing higher intake plus more movement, which led to a stall.

LevelBramble14archiveAug 14

Focus on hydration by adding a small amount of sea salt and lemon juice to each serving of water, keeping electrolytes calorie-free.

ClearQuill84archiveAug 14

I schedule at least one full fasting day weekly, something I did before these medications as well. The experience feels largely unchanged though appetite suppression makes it slightly easier now. The biggest ongoing requirement is keeping fluid intake high.

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Opinions on water fasting while on GLPs? · ZyraTrack Community