Does Stevia Break a Fast? Sweeteners While Fasting

In 30 seconds

Stevia and sucralose add little or no energy, so by the energy rule of the fasting trial cited here they would not break a fast; that is an inference from the rule, not a tested result. No trial cited here tested stevia, monk fruit or sucralose, so their effect on insulin, ketones or other fasting markers is not established. WHO conditionally advises against using non-sugar sweeteners for weight control.

• By the energy rule of the fasting trial cited here, lower- or no-calorie sweeteners add little or no energy.
• No trial cited here tested stevia, monk fruit or sucralose, so effects on fasting markers are not established.
• Aspartame is not suitable for people with phenylketonuria.

Does stevia break a fast?

The fasting trial cited here drew the line at energy: nothing with calories during the fasting window, but water and energy-free drinks, diet sodas included, were allowed. By that rule, a few drops of stevia in tea would not end the fast. That is an inference from the rule, not a tested result.

A 12-month time-restricted eating trial allowed water and energy-free drinks such as black tea, coffee and diet sodas, with a limit of two diet sodas a day, during the 16-hour fast.Source 11

Stevia, sucralose and monk fruit

Official guidance on sweeteners is about safety and weight, not fasting. Monk fruit is not among the examples on the NHS page (which is not a full list) or among WHO’s examples, so these sources say nothing specific about it.

NHS guidance describes sweeteners as lower- or no-calorie substitutes for sugar and lists steviol glycosides (stevia), sucralose and aspartame among those approved in the UK.Source 22

A 2023 WHO guideline conditionally recommends against using non-sugar sweeteners, including stevia, sucralose and aspartame, to control body weight; it is not a food-safety assessment.Source 33

Do sweeteners raise insulin?

None of the sources cited here measured insulin, blood sugar, ketones or autophagy after a sweetener during a fast, so this guide makes no claim either way.

NHS guidance describes the research on sweeteners and health as mixed and reports no evidence that sweeteners stimulate appetite in humans.Source 22

For the full list of drinks, see what you can drink while fasting and clean vs dirty fasting; coffee and diet soda have their own guides. For calorie numbers, see how many calories break a fast.

How strong is the evidence?

The 12-month fasting trial cited here defined the fast by energy and allowed energy-free drinks, diet sodas included. It did not test individual sweeteners, and the sweetener guidance cited here is about safety and weight, not fasting. Stricter rules are conventions, not findings.Source 11Source 22Source 33

Who should be careful?

Talk to a qualified health professional before fasting if you are pregnant or breastfeeding, under 18, living with or recovering from an eating disorder, have diabetes, take insulin or a medicine affected by meal timing, are an older adult, or are acutely ill. Do not change the dose or timing of any medicine without your clinician. See Blimbi’s safety guide.

Related guides

• What Can You Drink While Fasting?

  Water, black coffee and plain tea fit a zero-calorie fast; diet soda adds little or no energy. See what you can drink while fasting and what ends a fast.

• Dirty Fasting vs Clean Fasting: What's the Difference?

  Dirty fasting adds milk or broth; clean fasting means energy-free drinks. See what trials tested and why they set no calorie cutoff for a strict fast.

• Can You Drink Coffee While Fasting?

  Yes, if it's black: a 12-month trial allowed black coffee while fasting. See which additions end a fast, how much caffeine is too much and when to stop.

• Can You Drink Diet Soda While Fasting?

  Yes: diet soda has little or no energy, and a 12-month trial allowed up to two a day. See what sweeteners, caffeine and acidity add while fasting.

• Fasting-Mimicking Diet: What a 3-Month Trial Found

  The fasting-mimicking diet means 5 low-calorie days a month. A 3-month trial with commercial ties found lower weight and blood pressure. Its limits and who should avoid it.

Frequently asked questions

Does stevia break a fast?

Not by the energy rule the fasting trial cited here used, because stevia adds little or no energy. No trial cited here tested stevia itself, so its effect on insulin or ketones is not established.Source 11Source 22

Can you have sweeteners while fasting?

One 12-month trial allowed up to two diet sodas a day during the fast. Check labels for sugar, and note that WHO advises against using non-sugar sweeteners for weight control.Source 11Source 33

Do sucralose or monk fruit break a fast?

Neither was tested during a fast in the sources cited here. Sucralose is approved in the UK as a sugar substitute; monk fruit is not among the NHS page's examples, which are not a full list.Source 22

Sources

1. 1

   Time-Restricted Eating Without Calorie Counting for Weight Loss in a Racially Diverse Population: A Randomized Controlled TrialShuhao Lin et al. American College of Physicians, July 1, 2023.DOI: 10.7326/M23-0052 · PMID: 37364268Human randomized trial

2. 2

   The truth about sweetenersNHS. NHS, February 20, 2023.Official guidance

3. 3

   Use of non-sugar sweeteners: WHO guidelineWorld Health Organization. World Health Organization, May 15, 2023.Official guidance

4. 4

   Fasting Safely with DiabetesMartin M. Grajower. National Institute of Diabetes and Digestive and Kidney Diseases, August 26, 2020.Official guidance