Which magnesium is best while fasting?

Glycinate is gentle and good for sleep; citrate helps with regularity. Both are fast-safe.

Can magnesium help with fasting cramps?

The evidence is weak. No study has tested it on fasting cramps, and in a Cochrane review of ordinary muscle cramps it worked about as well as a placebo. If cramps keep coming back, talk to a doctor.

Should I take magnesium on an empty stomach?

It is generally fine; if it upsets your stomach, take it with your first meal.

Does Magnesium Break a Fast? No

Reviewed by the FastTrack team · Updated June 2026

Short answer: No

Magnesium does not break a fast. As a mineral it has no calories and does not raise insulin. Many people take it for cramps on longer fasts, though the evidence that it helps is weak.

Calories	0 kcal
Breaks a weight-loss fast?	No
Breaks ketosis?	No
Breaks autophagy?	No
Insulin impact	None

Why magnesium is fast-safe

Magnesium is an essential mineral with zero calories and no effect on insulin, so a supplement does not break a fast. It is one of the electrolytes the body sheds during longer fasts. People often take it for muscle cramps or restless sleep, but in trials on ordinary muscle cramps magnesium worked about as well as a placebo, so treat it as optional.

Form and timing

Plain magnesium capsules, glycinate, citrate, or as part of a sugar-free electrolyte mix, are all fast-safe. Avoid sweetened magnesium gummies, which add sugar. Magnesium glycinate in the evening is popular for sleep and does not break a fast.

How much is safe

A standard supplement dose is fine during a fast; if it upsets your stomach, take it with your first meal.

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Frequently asked questions

Does magnesium break a fast?: No, it is a calorie-free mineral with no insulin effect.
Which magnesium is best while fasting?: Glycinate is gentle and good for sleep; citrate helps with regularity. Both are fast-safe.
Can magnesium help with fasting cramps?: The evidence is weak. No study has tested it on fasting cramps, and in a Cochrane review of ordinary muscle cramps it worked about as well as a placebo. If cramps keep coming back, talk to a doctor.
Should I take magnesium on an empty stomach?: It is generally fine; if it upsets your stomach, take it with your first meal.