Does xylitol gum break a fast?

No for most goals. A piece has about 0.9 g of xylitol and roughly 2 calories.

Does xylitol raise insulin?

A little. Its glycemic index is around 7, and studies show a small insulin rise, far below sugar's.

Is xylitol or erythritol better for fasting?

Erythritol. It counts as 0 calories on US labels and barely moves blood sugar, while xylitol has 2.4 calories per gram.

Does xylitol break ketosis?

Not in normal amounts. A teaspoon has about 4 g of carbohydrate, but it raises blood sugar very little.

Does Xylitol Break a Fast? It Depends

Reviewed by the FastTrack team · Updated June 2026

Short answer: It depends

Xylitol is a grey area. It has about 2.4 calories per gram and only a small effect on blood sugar, so the gram or so in a piece of gum or a mint will not break a fast. Spoonfuls in coffee are another matter: a teaspoon adds about 10 calories, which builds up over a day.

Calories	~2.4 kcal per gram, ~10 per tsp
Breaks a weight-loss fast?	Partial
Breaks ketosis?	No
Breaks autophagy?	Partial
Insulin impact	Low

Why xylitol is a grey area

Xylitol is a sugar alcohol that the body only partly absorbs. The FDA uses 2.4 calories per gram for food labels, about 60% of sugar's 4. Its glycemic index is around 7, against about 65 for table sugar, and studies show a small insulin rise, lower than sugar's and higher than water's. A little changes almost nothing, while larger amounts break a fast defined by calories or done for autophagy.

Gum, mints and how much is too much

A piece of xylitol gum holds about 0.9 g, roughly 2 calories, fine on any fast short of a strict water fast. A teaspoon or two in coffee several times a day adds 20 to 50 calories, and large amounts cause bloating and diarrhea for many people. A 2024 observational study linked higher blood xylitol to more heart attacks and strokes in people at risk; it still needs confirmation. Xylitol is also highly toxic to dogs.

How much is safe

Gum or mints with xylitol are fine during a fast. If you sweeten drinks, keep it to a teaspoon, or switch to erythritol, stevia or monk fruit, which have essentially no calories.

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Frequently asked questions

Does xylitol gum break a fast?: No for most goals. A piece has about 0.9 g of xylitol and roughly 2 calories.
Does xylitol raise insulin?: A little. Its glycemic index is around 7, and studies show a small insulin rise, far below sugar's.
Is xylitol or erythritol better for fasting?: Erythritol. It counts as 0 calories on US labels and barely moves blood sugar, while xylitol has 2.4 calories per gram.
Does xylitol break ketosis?: Not in normal amounts. A teaspoon has about 4 g of carbohydrate, but it raises blood sugar very little.