Coffee is fine. Your caramel latte is a dessert.
Black coffee is one of the best-studied drinks on the planet, and it fits into your fasting window. The syrup, the whipped cream and the four spoons of sugar don't. Here's how to take them out without hating your mornings.
The short version
- Best
- Black coffee, espresso, kopi-O kosong, plain tea.
- OK
- Cappuccino, flat white, kopi-C kosong, a Melange: milk, no sugar.
- Never
- Syrups, frappés, sugar, sweeteners, "sugar-free" syrups, 3-in-1 sachets.
- When
- Black any time before early afternoon. Milk only inside your eating window.
- Our take
- Coffee is a drink. The moment it needs a straw and a lid of cream, it's a cake.
The one rule: coffee is black until you're eating
Your plan works because your body gets long breaks from food. Black coffee doesn't end that break: a cup has about 2 calories and no sugar.1 Milk does. It's food, with protein, fat and milk sugar. So black in the fasting window, milk in the eating window, and sugar in neither. If you follow time-restricted eating, this is the bit that makes mornings easy.
What coffee does to your body
The coffee itself: mostly good news
The biggest review of the evidence pooled more than 200 meta-analyses. Coffee was more often linked with benefit than harm. People drinking three to four cups a day had about 17% lower risk of dying early than people drinking none, and lower risk of heart disease.2 Honest caveat: almost all of that is observational. Coffee drinkers may simply be different people. It is still no reason to quit, and no reason to start drinking ten cups.
Exceptions from the same review: in pregnancy, higher intake went with lower birth weight and pregnancy loss, and women had a higher fracture risk with heavy drinking.2
Caffeine: how much is too much
The European Food Safety Authority says up to 400 mg of caffeine a day is fine for healthy adults, and up to 200 mg in one go. In pregnancy and while breastfeeding, the limit is 200 mg a day. An espresso has around 80 mg, a 200 ml cup of filter coffee around 90 mg.3 That's about four cups of filter coffee a day. A Venti is not one cup.
Caffeine and your sleep
In a home study, 400 mg of caffeine taken six hours before bed still cut sleep by more than an hour.4 A 2023 review of 24 studies found caffeine took about 45 minutes off total sleep and cut deep sleep. Its authors suggest a regular coffee at least about 9 hours before bed.5 And short sleep has its own price, which we cover in late-night snacking. So the 4 pm latte costs you twice: once in sugar, once in sleep.
The sugar: where it all goes wrong
The WHO wants free sugars under 10% of your energy, ideally under 5%: about 25 g, or six teaspoons, a day. Sugar that's naturally in milk doesn't count.6 Now look at the menu. When the charity Action on Sugar tested 131 flavoured hot drinks from UK chains, 98% would get a red "high sugar" label, and 35% had as much sugar as a can of cola or more. A large chai latte had 20 teaspoons. A Venti white chocolate mocha with cream had 18.7 That's three days of sugar before lunch.
Cup by cup
Added sugar per cup. Kopi values from HealthHub Singapore,8 chain drinks from the Action on Sugar survey.7 Recipes and sizes vary.
| Drink | Added sugar | Verdict |
|---|---|---|
| Black coffee, espresso, Americano, kopi-O kosong | 0 tsp | Any time |
| Cappuccino, flat white, latte, Melange, kopi-C kosong (no sugar added) | 0 tsp | Eating window |
| Kopi-C siu dai | ~2.9 tsp | Step down |
| Kopi, standard order | ~4 tsp | Step down |
| Caramel or flavoured latte (Caffe Nero Caramelatte) | ~13 tsp | Never |
| White chocolate mocha with cream (Venti) | ~18 tsp | Never |
| Chai latte (large) | up to ~20 tsp | Never |
| Frappés, iced blended drinks, 3-in-1 sachets | check the label | Never |
The step-down plan: three weeks to black (or nearly)
Nobody goes from a daily caramel macchiato to espresso overnight. Don't try. Do this instead:
- Week 1: halve it. Half the syrup pumps, half the sugar. Two spoons become one. Kopi becomes kopi siu dai. Smallest cup size, always.
- Week 2: drop the syrup. Plain latte or cappuccino, one small spoon of sugar at most. Add cinnamon or cocoa powder on top if you miss the flavour.
- Week 3: no sugar. Milk coffee only, nothing added. Kopi-C kosong. Your first cup of the day, before you eat, goes black.
- Week 4, optional: black most of the time. One milk coffee with a meal. The rest black, or plain tea.
Will you ever like it? Probably. In a small trial, people who cut their sugar for three months rated sweet puddings about 40% sweeter than people who didn't change.9 Your taste adjusts. The old drink will start tasting too sweet. That's the goal.
"Sugar-free syrup is the smart swap." It's sweetener, and sweeteners are on our never list. They keep the sweet habit alive, so the step-down never happens. We'd rather you have one real spoon of sugar in week 2 than zero-calorie syrup forever.
"Coffee dehydrates you." Not at normal amounts. In a trial with 50 regular coffee drinkers, four cups a day hydrated them just as well as the same amount of water.10 Small study, all men, but the result is clear. You don't need to "pay back" every espresso.
"Oat milk is the healthy milk." It's a plant drink, not a health drink. Barista versions usually list oil, and some list sugar, so they foam like the real thing. Read the ingredients: you want oats, water, maybe salt. Unsweetened, or skip it.
Drink, forget
Drink
- Espresso, ristretto, Americano, filter coffee
- Kopi-O kosong, cold brew without sugar
- Cappuccino, flat white, latte, without sugar (eating window)
- Unsweetened soy or almond drink
- Cinnamon, cocoa powder, cardamom on top
- Green tea, black tea, herbal tea
Forget it
- Flavoured syrups, including "sugar-free" ones
- Frappés, iced blended drinks, whipped cream
- Condensed milk, sweetened creamer
- 3-in-1 and 2-in-1 coffee sachets
- Bottled and canned coffee drinks with sugar
- Sweeteners and "zero" coffee drinks
- Irish coffee and coffee liqueurs
Irish coffee is two problems in one cup: sugar and alcohol. If you drink, our alcohol guide has the better options. And an energy drink is not a coffee upgrade, see energy drinks.
Eat it where you live
Singapore and Southeast Asia
- Learn the code: kosong is no sugar, siu dai is less sugar, O is no milk, C is evaporated milk. Kopi-O kosong is the goal, kopi-C kosong is fine with a meal.
- Standard kopi comes with about 4 teaspoons of sugar.8 Siu dai is a step, not the finish line.
- Vietnamese and Thai iced coffee are made with condensed milk. Ask for black, with ice.
- Kopi peng is fine as kopi-O kosong peng.
Austria, Germany, Switzerland
- A Kleiner Schwarzer, Verlängerter or Melange without sugar is perfect.
- Skip the Einspänner and the Wiener Eiskaffee: cream and ice cream are dessert.
- Kaffee und Kuchen: keep the coffee, make the cake a Rebel Day thing (see office cake).
- Boiled coffee, Turkish coffee and French press keep the oils that paper filters catch. Those raise LDL cholesterol; filtered coffee barely does.11
Can't drink coffee without sugar?
- Keep one small spoon of real sugar, in one cup a day, and stop there
- Smallest size, always. A small latte is half the problem of a large one
- Use warm frothed milk: it tastes sweeter than cold milk, with nothing added
- Add cinnamon, vanilla seeds or cocoa powder instead of syrup
- Have your sweet coffee straight after a meal, never as breakfast
Still a no: syrups, sweeteners, frappés, and milk or sugar during your fasting window.
Allergies and intolerances
Plain coffee is not on the EU list of 14 allergens. What goes in it often is.12
| In your cup | EU allergen | Swap |
|---|---|---|
| Milk, cream, condensed and evaporated milk | Milk | Black, or unsweetened soy or oat drink |
| Soy drink | Soy | Oat drink or coconut drink, unsweetened |
| Almond, cashew or hazelnut drink | Nuts | Oat or soy drink |
| Oat drink | Cereals containing gluten (cross-contact) | Certified gluten-free oat drink, or soy |
| Biscotti, cantuccini, the biscuit on the saucer | Gluten, egg, often nuts | Leave it on the saucer |
Lactose intolerant? Lactose-free milk works the same way. It tastes a bit sweeter because the milk sugar is already split, but no sugar is added.
Talk to your doctor first if you…
- are pregnant or breastfeeding: keep caffeine to 200 mg a day, about two small cups3
- have heart rhythm problems, high blood pressure or anxiety that caffeine makes worse
- have reflux or stomach problems that flare with coffee
- have high LDL cholesterol and drink boiled, Turkish or French press coffee
- take medication that interacts with caffeine: ask your pharmacist
How coffee fits into your plan
Black coffee and plain tea are allowed in your fasting window, every day. Milk coffee belongs in your eating window, ideally with a meal. Your Healthen me answers decide the rest: if you're pregnant, sensitive to caffeine or sleep badly, your plan keeps you to fewer cups and none after midday.
On Rebel Day, have the frappé if you really want it. Then notice how sweet it tastes after three weeks without. Not on the fasting day after, though: that's water, black coffee and green tea.
This article is general information, not medical advice. If you have a medical condition, are pregnant or take medication, talk to your doctor about how much caffeine is right for you.
Sources
- US Department of Agriculture. FoodData Central (brewed coffee, energy per 100 g). fdc.nal.usda.gov
- Poole R, Kennedy OJ, Roderick P, Fallowfield JA, Hayes PC, Parkes J. Coffee consumption and health: umbrella review of meta-analyses of multiple health outcomes. BMJ 2017;359:j5024. doi.org/10.1136/bmj.j5024
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the safety of caffeine. EFSA Journal 2015;13(5):4102. doi.org/10.2903/j.efsa.2015.4102; caffeine per cup from EFSA's caffeine topic page, efsa.europa.eu/en/topics/topic/caffeine
- Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. Journal of Clinical Sleep Medicine 2013;9(11):1195–1200. doi.org/10.5664/jcsm.3170
- Gardiner C, Weakley J, Burke LM et al. The effect of caffeine on subsequent sleep: a systematic review and meta-analysis. Sleep Medicine Reviews 2023;69:101764. doi.org/10.1016/j.smrv.2023.101764
- World Health Organization. Guideline: sugars intake for adults and children. Geneva: WHO, 2015. who.int
- Action on Sugar. Hot flavoured drinks survey, February 2016 (131 drinks from UK coffee shops and fast food chains). Charity survey, not peer-reviewed. actiononsugar.org/surveys/2016/hot-flavoured-drinks
- Health Promotion Board Singapore, HealthHub. Reduce sugar content in drinks: say siu dai instead for a healthier brew. healthhub.sg/live-healthy/762/say-siu-dai-instead
- Wise PM, Nattress L, Flammer LJ, Beauchamp GK. Reduced dietary intake of simple sugars alters perceived sweet taste intensity but not perceived pleasantness. American Journal of Clinical Nutrition 2016;103(1):50–60. doi.org/10.3945/ajcn.115.112300
- Killer SC, Blannin AK, Jeukendrup AE. No evidence of dehydration with moderate daily coffee intake: a counterbalanced cross-over study in a free-living population. PLoS ONE 2014;9(1):e84154. doi.org/10.1371/journal.pone.0084154
- Jee SH, He J, Appel LJ, Whelton PK, Suh I, Klag MJ. Coffee consumption and serum lipids: a meta-analysis of randomized controlled clinical trials. American Journal of Epidemiology 2001;153(4):353–362. doi.org/10.1093/aje/153.4.353
- Regulation (EU) No 1169/2011 on food information to consumers, Annex II (the 14 allergens). eur-lex.europa.eu/eli/reg/2011/1169/oj