Three ways to define "breaking"
- Calories (weight loss) — Weight loss comes down to total daily intake. Brewed coffee has about 1 kcal per 100 g, so black coffee is close to zero.
- Habit (cutting late-night snacking) — The rule "nothing to chew outside the window" matters more than calories. Allowing a latte or a cookie tends to unravel the rule.
- Medical tests (fasting before blood work) — A different thing entirely. Follow the clinic’s instructions exactly, even if they say water only.
Johns Hopkins Medicine’s guide lists water and zero-calorie drinks such as black coffee and tea as acceptable during fasting periods.
Drink and supplement cheat sheet
| Item | If the goal is weight loss | Note |
|---|---|---|
| Water, sparkling water | Fine | Staying hydrated is encouraged |
| Black coffee, americano | Generally fine | Syrups and cream are another story |
| Unsweetened tea | Generally fine | Check labels on sweetened tea |
| A spoon or two of milk | Small, but not zero | Pick a rule and keep it consistent |
| Latte, mocha | Basically a meal | Move it into your eating window |
| Zero-calorie soda | Nearly no calories | Notice whether sweetness makes you hungrier |
| Coffee with butter or oil | High in calories | Does not fit a fasting period |
| Medication, supplements | Prescriptions as directed | Some drugs should not be taken on an empty stomach |
If your medication schedule clashes with your eating window, ask your doctor or pharmacist first. Never skip or delay medication to fit a fast.
Caffeine on an empty stomach
Even without calories, coffee on an empty stomach can cause heartburn or jitters for some people, and long fasts can turn coffee into a hunger suppressant. Late coffee also hurts sleep, so see caffeine cutoff before bed. Whether coffee counts toward hydration is covered in does coffee count as water.
Logging it in the app
Keep the fast running
Black coffee, water and tea are no reason to stop the timer. While fasting, tap + next to "Water intake" for each cup of water. Whether coffee counts as a cup is your call.
Had a latte? Stop honestly
If you drank something closer to a meal, tap "Stop Fasting" so your stats stay trustworthy. If you missed the moment, fix the end time later with the pencil (Adjust times) button in the History tab.
FAQ
What about gum or mints?
Sugar-free gum is very low in calories, but chewing can trigger appetite for some people. Sugary candy is easier to move into the eating window.
How many cups of coffee are okay while fasting?
Total caffeine and sleep matter more than fasting rules here. If you have a heart condition or are pregnant, ask your doctor about caffeine limits.
Sources: Johns Hopkins Medicine, Intermittent Fasting · USDA FoodData Central, brewed coffee
Intermittent Fasting Timer: 16:8 Diet & Fasting Log
No sign-up, works offline, and your fasting log stays on your phone. Free on Android, in English and Korean.