What Can You Eat and Drink While Fasting?

What Can You Eat and Drink While Fasting?

During your fasting window you should eat nothing at all, and drink only calorie-free liquids: plain water, sparkling water, black coffee, and plain tea. Anything with calories — milk, sugar, juice, broth, or snacks — ends the fast. Water and salt are the two things that matter most.

Why This Matters

Most people who quit intermittent fasting do not quit because they were hungry. They quit because they felt weak, dizzy, or headachy in the first week, decided fasting "did not agree with them," and stopped. Almost every one of those symptoms comes from dehydration and low sodium, not from lack of food.

The other half of the problem is confusion. One article says black coffee is fine, another says it ruins everything. Someone adds a splash of milk "because it's only 15 calories." Someone else drinks a diet soda and worries all day. Knowing exactly what is allowed removes the anxiety, and a fast you are not anxious about is a fast you can repeat tomorrow.

What Actually Breaks a Fast

The simplest working rule: if it has calories, it breaks the fast. If it has zero calories and no sweet taste, it does not.

Always safe:

• Plain water — still or sparkling, cold or room temperature. Aim for 2 to 3 litres across the day.
• Black coffee — no milk, no sugar, no cream. Around 2 calories per cup. It also blunts appetite and slightly increases fat oxidation, which is why many people find fasting easier with it.
• Plain tea — black, green, white, or herbal. Persian favourites like چای and mint or chamomile infusions are all fine unqualified, as long as nothing is added.
• Salt — a pinch of sea salt in your water, or salt dissolved on the tongue. Zero calories, and it fixes most fasting headaches.

Grey area — technically fine, but be careful:

• Diet drinks and zero-calorie sweeteners. They contain no calories and will not break the fast in a metabolic sense. But the sweet taste triggers cravings in many people, and that is what makes them dangerous. If they help you get through the window, use them. If they leave you hunting for food, drop them.
• Apple cider vinegar — a teaspoon in water is about 1 calorie. Harmless, though it does not do the magic things the internet claims.

Breaks the fast, no matter what you have read:

• Milk, cream, or non-dairy milk in coffee — even a small amount contains protein and sugar, which trigger insulin.
• Bone broth. It is nourishing food, and useful, but it is food.
• Juice, smoothies, sports drinks, and sweetened tea.
• BCAAs, protein powder, and most flavoured supplements.
• Chewing gum and mints, if sweetened. Sugar-free gum is borderline; a stick or two is not going to undo a 16-hour fast.
• Fruit — including a single date. This matters especially around Ramadan habits, where a date is the traditional way to open the fast, and rightly so: it is the signal that the fast is finished, not a fasting-window food.

Practical Tips

Drink before you are thirsty. Set a bottle on your desk and finish it before noon. Most "fasting fatigue" disappears when you fix hydration.

Add salt if you feel a headache coming. A quarter teaspoon of salt in a glass of water usually clears a fasting headache in fifteen minutes. When you stop eating you also stop taking in sodium, and your kidneys flush what is left.

Keep coffee before mid-afternoon. Caffeine has a half-life of around six hours. Fasting already raises alertness; caffeine at 6pm plus a fasted body often means poor sleep, and poor sleep makes tomorrow's fast much harder.

Do not use warm drinks as a substitute for eating all evening. Hot tea in the last two hours before bed is comforting and genuinely dulls hunger — this is the single most useful trick for people fasting through evening hours.

Break the fast gently. After 16 hours, do not open with sugar and bread. Protein and fat first — eggs, yoghurt, nuts, or a normal cooked meal — keeps blood sugar steady and prevents the crash-and-binge cycle that ruins so many fasting days.

Watch what you drink after the window closes too. The eating window is not a free pass. A fast followed by three glasses of sweet drink undoes the whole day's work.

Get the Complete Guide

For the complete intermittent fasting guide, get Intermittent Fasting in Practice on Amazon — and claim 3 months free on our fasting app at fastinginpractice.com/redeem

Frequently Asked Questions

Does black coffee really not break a fast?

Correct. A cup of black coffee has roughly 2 calories and does not produce a meaningful insulin response. It is one of the few things that genuinely makes fasting easier rather than harder. The moment you add milk or sugar, that changes.

How much water should I drink while fasting?

Between 2 and 3 litres across the day, more in hot weather or if you train. Because you are not getting the water that normally comes from food, your intake needs to be higher during fasting days, not the same.

Can I take my supplements or medication during the fasting window?

Medication should always be taken as your doctor prescribed — never skip a dose to protect a fast. Fat-soluble vitamins (A, D, E, K) absorb poorly on an empty stomach, so move them to your eating window. Water-soluble vitamins are fine anytime.

Will a small amount of milk in my tea really matter?

For a 16:8 fast aimed at weight loss, a splash of milk once a day will not destroy your results. But it does break the fast technically, and more importantly it opens the door to "just a little" becoming a habit. Cleaner is simpler, and simpler lasts longer.