Ready to try your first fast? Lovely. Start smaller than you think. A good first target is 12 to 13 hours, with most of it happening while you're asleep.
Here's how that might look. You finish dinner around seven in the evening, head to bed, and have breakfast at eight. Sleep does the heavy lifting, so you're only awake and fasting for a couple of hours. Not scary at all.
Stick with that for a week or so. If it feels easy, add an hour. If it doesn't, stay where you are, or drop back a little. There's no prize for going longer. Skipping the heroics usually makes it much more likely you'll keep going, and keeping going is what counts.
A few small things often help. Eat a proper dinner so you're not starting on empty. Drink plenty of water. Pick a calm day rather than a packed one. And notice how you feel: hungry, sleepy, grumpy, fine? The notes in Step Step are a handy place to jot it down, so you can spot patterns after a few fasts.
If you ever feel dizzy, unwell or just plain awful, stop and eat something. That's not failing. It's your body giving you feedback, and listening to it is part of the plan.
How long should your first fast be?
Aim for 12 to 13 hours, and let sleep do most of it. If dinner ends at seven and breakfast is at eight, you have already fasted for 13 hours. Your first fast may be something you have done for years without noticing.
Plenty of people want to leap straight to 16 hours or a full day. It is tempting, but a big first fast often ends in a headache, a grumpy afternoon and a large snack, which makes the next attempt feel worse. A small target you can repeat beats a heroic one you do once.
If 12 hours feels easy after a week, try 13, then 14, adding an hour only when the current length feels boring. If you feel hungry before bed, that is useful to know too. It may mean dinner should be bigger or later, which is a better fix than pushing through.
What should you do the day before and the evening before?
Plan the evening meal. A proper dinner with some protein, vegetables and something starchy, such as rice, potatoes or bread, will carry you further than a light snack. Going to bed having eaten too little is a common reason a first fast feels hard.
Drink water through the evening, and keep alcohol low, since it can disturb sleep and make the morning rougher. Decide in advance when the kitchen closes, then do something that is not near food: a bath, a walk round the block, a book.
If you take medication, or you have diabetes, speak to your doctor before changing when you eat. Some tablets need food, and some affect blood sugar.
How do you get through the first morning?
Start with a glass of water. Many people mistake thirst for hunger first thing, and a drink can settle things for a while. Black coffee or plain tea are usually fine for most people, as long as they do not leave you jittery.
Keep your hands and head busy. A first fast is much harder when you sit and watch the clock. Plan a walk, a shower, a call or a task you have been putting off. Hunger often comes in waves rather than climbing steadily, so if it is strong at nine o'clock it may be gentler by ten.
When your window opens, do not rush to a huge meal. Start with something simple and balanced, eat at an ordinary speed, and see how you feel half an hour later. Very large, very sugary first meals can leave you sleepy.
When should you stop a fast and eat?
Stop and eat if you feel dizzy, faint, shaky, sick, confused or very unwell. Mild hunger, a rumbling stomach or a slightly low mood are normal. Feeling truly ill is not, and ending the fast early is the sensible response.
After your first attempt, write down what you noticed: when you felt hungry, how you slept, what was easy. A few notes are enough to show you what to change next time. If it went well, repeat the same fast for about a week before adding an hour. If it did not, try again at 11 or 12 hours.
It also helps to treat the first few attempts as experiments. You are not testing your willpower, you are finding out what suits your body and your routine. Some people feel sharper in the morning without food, while others feel flat until they have eaten. Both are ordinary. Keep a light plan for the day after, too, so a slightly rough fast does not turn into a rough week.
Common questions
How long should a beginner fast for the first time?
Around 12 to 13 hours, most of it overnight, is a gentle first target. Repeat it for a week or so before adding an hour.
What should I eat before my first fast?
A proper, balanced dinner with protein, vegetables and some starchy food usually works well. Avoid going to bed hungry or on a very light meal.
Can I drink coffee on my first fast?
Plain black coffee or unsweetened tea is usually fine, though coffee on an empty stomach makes some people jittery. Water is always a good choice.
What if I get a headache while fasting?
Drink some water first, as mild dehydration is a common cause. If the headache stays or you feel unwell, stop the fast and eat something.
Updated October 25, 2026
This is general information, not medical advice. Check with your doctor before you start fasting, especially if you have a health condition, are pregnant or take medication.
