Creatine and Fasting: Can You Take It During a Fast?
Whether you are fasting for Yom Kippur, Tisha B'Av, or intermittent fasting, here is what the science says about creatine and fasting.
The Fasting Question
For observant Jews, fasting is a regular part of religious life — Yom Kippur, Tisha B'Av, and several other fast days throughout the year. If you supplement with creatine, a natural question arises: can you take it during a fast?
This question also applies to those who practice intermittent fasting for health or weight management purposes.
Does Creatine Break a Religious Fast?
This is ultimately a halachic question that should be addressed with your rabbi. From a purely physiological standpoint, creatine monohydrate contains no calories and no significant metabolic substrates that would be considered "eating." However, you need to consume creatine either in liquid if it's a powder or in a gummy form which would suggest it breaks the fast but consult a qualified posek.
What Happens to Creatine Stores During Fasting?
Creatine is stored in muscle tissue as phosphocreatine. These stores are not rapidly depleted during a 24–25 hour fast. The body's creatine pool turns over slowly — approximately 1–2% of intramuscular creatine is degraded to creatinine and excreted in urine each day. [1] A single fast day will not meaningfully deplete your creatine stores.
Creatine and Intermittent Fasting
For those practicing intermittent fasting (e.g., 16:8 or 18:6 protocols), creatine can be taken during the eating window without any loss of effectiveness. Research on creatine timing consistently shows that the timing of creatine ingestion relative to meals is less important than daily consistency. [2]
A 2020 randomized controlled trial by Ribeiro et al. found that creatine supplementation on training days only (rather than daily) still produced greater gains in muscle strength and endurance compared to placebo, suggesting that even non-daily supplementation maintains meaningful benefits. [3]
Practical Guidance
| Scenario | Recommendation |
|---|---|
| Yom Kippur / Tisha B'Av | Consult your rabbi; creatine stores will not deplete meaningfully in 25 hours |
| Intermittent fasting | Take creatine during your eating window — timing does not significantly affect outcomes |
| Pre-fast preparation | Consistent daily supplementation in the days before a fast maintains creatine stores |
The Bottom Line
From a scientific standpoint, a single fast day will not deplete your creatine stores. For intermittent fasting, take creatine during your eating window. For religious fasts, consult your rabbi on the halachic question.
References
1. Kreider RB, Kalman DS, Antonio J, et al. International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine. J Int Soc Sports Nutr. 2017;14:18. https://doi.org/10.1186/s12970-017-0173-z (PMC5469049)
2. Antonio J, Ciccone V. The effects of pre versus post workout supplementation of creatine monohydrate on body composition and strength. J Int Soc Sports Nutr. 2013;10:36. https://doi.org/10.1186/1550-2783-10-36
3. Ribeiro F, Longobardi I, Perim P, et al. Effects of creatine supplementation during resistance training on lean body mass and strength in older adults: a systematic review and meta-analysis. Nutrients. 2021;13(6):1985. https://doi.org/10.3390/nu13061985
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