What Breaks a Fast checks 237 drinks, foods, supplements, sweeteners and medicines against three fasting goals: weight loss, autophagy and insulin control. Pick your goal, search an item, and the checker tells you whether it won’t break your fast, might break it, or breaks it. The answer is about your fast, not about whether an item is safe for you; for supplements and medicines, ask a clinician.
Last verified 6 Oct 2026 against the checker’s item data and the six FDA, NIH Office of Dietary Supplements and NCCIH pages behind its safety notes.
Food and drink checker
Search common drinks, foods, and supplements. The answer changes with your goal, so choose weight loss, autophagy, or insulin control before you decide.
Common checks, answered clearly
Use these as a quick reference. Open an item for portions, ingredients, and goal-specific reasoning.
| Item | Weight loss | Autophagy | Insulin control | Why |
|---|
Simple rule
If it has meaningful calories, count it.
For stricter goals, ingredients and dose matter even when the label says zero.
How the verdict is worked out
The checker does not calculate a verdict from a formula. Each item in its list carries three verdicts, one for each goal, which the FitnessVolt editors set, along with the item’s nutrition data, an explanation and tips.
1. The item data
Every item holds its calories, carbohydrate, protein and fat for a typical serving, an insulin-response label from none to high, and a verdict for each goal. The list covers five groups.
| Group | Items |
|---|---|
| Drinks | 70 |
| Supplements | 58 |
| Sweeteners | 16 |
| Foods | 63 |
| Medications | 30 |
2. One verdict per goal
The same item can get a different verdict for each goal, because each goal tolerates different things. In the current list:
- Weight loss: every item rated “Won’t break your fast” has 10 calories or fewer.
- Autophagy: every item rated “Won’t break your fast” has 6 calories or fewer and no protein, and every item with protein might break or breaks the fast.
- Insulin control: the verdict follows the insulin-response label more than the calories. Every item labelled high breaks the fast, and some fats with no carbohydrate, such as olive oil, won’t break it.
| Goal | Won’t break your fast | Might break your fast | Breaks your fast |
|---|---|---|---|
| Weight loss | 105 items | 53 items | 79 items |
| Autophagy | 97 items | 40 items | 100 items |
| Insulin control | 135 items | 46 items | 56 items |
The quick-reference table answers “Does it break a fast?” with the same verdicts in short form: No, Depends or Yes.
3. Search
The search compares what you type with item names and group names and suggests up to eight matches. Check item opens the first match. If nothing matches, the checker suggests other searches instead of guessing.
4. Safety notes
The tips under each item carry its safety notes. Six of them come from government sources:
- Iron supplements: keep them out of reach of children. US law requires iron supplement labels to warn that accidental overdose of iron-containing products is a leading cause of fatal poisoning in children under 6.
- Calcium with iron: take the two at different times of day. The NIH Office of Dietary Supplements notes that experts recommend this to avoid interference with iron absorption.
- Caffeine in coffee, tea, caffeine pills and pre-workouts: the FDA cites 400 mg a day as an amount not generally linked with negative effects for most adults, and asks you to talk to your health care provider if you are pregnant, trying to become pregnant, breastfeeding, or take medicines.
- Green tea extract: ask a clinician first. The NIH National Center for Complementary and Integrative Health reports rare liver injury, in most cases from green tea extract in tablets or capsules.
- Berberine: ask a clinician about the dose and tell them about any medicines you take, including for diabetes. The same center notes that dietary supplements may interact with medications.
- Biotin: tell your doctor you take it before a blood test. The NIH Office of Dietary Supplements notes that biotin beyond recommended intakes can make some lab results read too high or too low.
For prescription medicines the tip is always the same: ask your prescriber before you change how or when you take it, and do not skip a medication to fast.
Worked example: three items, one goal
With the default goal, weight loss, we searched three items in the checker. Each one lands on a different verdict.
| Item | Data the checker shows | Verdict for weight loss |
|---|---|---|
| Black coffee | 2 calories, 0 g carbohydrate, 0 g protein, 0 g fat | Won’t break your fast |
| Bone broth | 40 calories, 0 g carbohydrate, 9 g protein, 1 g fat | Might break your fast |
| Kombucha | 30 calories, 7 g carbohydrate, 0 g protein, 0 g fat | Breaks your fast |
Switch the goal and bone broth changes: it breaks your fast for autophagy, because of its 9 g of protein, and won’t break it for insulin control.
What breaks a fast questions
Does black coffee break a fast?
No, for all three goals. The checker lists black coffee at 2 calories with no carbohydrate, protein or fat. Cream, sugar and sweeteners change the answer. Count its caffeine toward the FDA’s 400 mg a day for most adults.
Can I take vitamins or medicines while fasting?
Most vitamin and mineral supplements in the list have no calories, so they won’t break your fast. Gummies and chews can hold sugar: gummy vitamins, at about 15 calories, break your fast for every goal. For prescription medicines, ask your prescriber before you change how or when you take them, and do not skip a medication to fast.
Does gum break a fast?
Sugar-free gum has about 5 calories in the checker’s data. It won’t break your fast for weight loss or insulin control, and it might break it for autophagy.
Will bone broth break my fast?
It depends on your goal. At 40 calories and 9 g of protein, bone broth breaks your fast for autophagy, might break it for weight loss, and won’t break it for insulin control.
Do zero-calorie energy drinks break a fast?
The checker rates them “Might break your fast” for all three goals, the same as diet soda, because of their sweeteners. Check the label for caffeine: many cans hold a lot.
Sources
- 21 CFR 101.17(e): warning statement for iron-containing supplements. US Food and Drug Administration, Electronic Code of Federal Regulations.
- Iron: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, updated 4 September 2025.
- Spilling the Beans: How Much Caffeine is Too Much? US Food and Drug Administration, content current as of 28 August 2024.
- Green Tea: Usefulness and Safety. NIH National Center for Complementary and Integrative Health, updated 15 May 2024.
- Diabetes and Dietary Supplements: What You Need To Know. NIH National Center for Complementary and Integrative Health.
- Biotin: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements, updated 10 January 2022.
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