- Intermittent fasting sets when you eat, not what you eat. You split the day into an eating window and a fasting window.
- The most common schedules are 12:12, 14:10 and 16:8. Start with the easiest and move up based on how you feel.
- Results depend mainly on your total calorie intake. Fasting is just a way to organize your meals.
- It isn't for everyone: pregnant or breastfeeding women, minors and people with an eating disorder shouldn't try it.
You'll find intermittent fasting everywhere, from social media to family lunches. It sounds complicated, but the principle is simple: you eat only within a certain time window and go without calories for the rest of the day. This guide explains how it works, what you can realistically expect and how to start without unnecessary struggle.
What intermittent fasting is and isn't
Intermittent fasting isn't a diet in the traditional sense. It doesn't tell you which foods are off limits, only the time range in which you can eat them. For example: breakfast at ten, your last meal at six in the evening and no calories in between.
Let's be clear from the start. Fasting is not a magic fat burner. If you eat more in your window than your body uses, you won't lose weight. If you eat less, you will, just as with any other way of eating. Fasting can help if you like a fixed structure to your day, if you want to stop late-night snacking or if you're tired of constantly deciding about food. But the foundation is still healthy, sustainable weight loss through a sensible energy intake.
The most common schedules: 12:12, 14:10 and 16:8
The number before the colon is the hours of fasting, the number after it is the hours you can eat. You usually sleep through much of the fast, so it's easier than it sounds.
| Schedule | Fasting | Eating window | Example |
|---|---|---|---|
| 12:12 | 12 hours | 12 hours | Eating from 7:00 to 19:00 |
| 14:10 | 14 hours | 10 hours | Eating from 8:00 to 18:00 |
| 16:8 | 16 hours | 8 hours | Eating from 11:00 to 19:00 |
12:12 is only a slight tweak to your daily rhythm: no eating at night and no snacking after dinner. It's the easiest way to start. 16:8 is the most popular, but it requires you to cope with hunger. We don't recommend longer fasts, such as 24 hours or more, for beginners.
How to start: a plan for the first two weeks
- Pick an easy schedule. Start with 12:12. If it goes well, try 14:10 after a week.
- Choose a window that fits your day. If you like breakfast, keep it and stop eating earlier in the evening. If you're not hungry in the morning, start eating later.
- Drink during the fast. Water, unsweetened tea and black coffee won't break your fast. There's more in the How much water to drink guide.
- Eat properly in your window. Include protein, vegetables and a source of carbs. If you only eat sweets in your window, you'll be hungry sooner.
- Watch how you feel. If you get dizzy, have headaches or can't sleep, lengthen your eating window and try an easier schedule.
You don't have to keep the same fast every day. Many people like 16:8 on workdays and a looser routine on weekends. What matters is that you can keep it up long term.
What to drink and eat during and outside the fast
During your fasting window, drink water, unsweetened tea or black coffee. Sweetened drinks, milk in coffee, honey and juices all contain calories, so they break the fast. When you're hungry, a glass of water or a warm tea can help, because we sometimes mistake hunger for thirst.
In your eating window, the usual rules apply: a varied diet, enough protein, vegetables and sensible portions. You can find out how much to eat in the calculator. Then split your daily goal into two or three meals. Our guide to counting calories can help too.
Don't break the fast with a huge portion. If you eat more slowly and include protein and fiber, you'll feel full sooner and won't eat your whole daily intake in one meal.
What you can realistically expect
Many people come to like fasting because it simplifies their day: fewer decisions, less evening snacking, clear rules. For some it naturally lowers their calorie intake. For others it doesn't suit them at all and they feel tired or irritable. Both experiences are normal.
Don't fall for promises of rapid fat burning, detox or miracle effects. They aren't backed up. Fasting is just one tool, and it only works if you can stick to it and it doesn't get in the way of everyday life.
It fits into the bigger picture of improving your habits, but sleep, movement and a steady routine will help you more than any rule about hours. You'll find more in the Healthy lifestyle habits guide.
Who intermittent fasting isn't for
Intermittent fasting isn't suitable for pregnant or breastfeeding women, minors, people who have had an eating disorder, or people who are underweight. If you have diabetes and take medication or insulin, fasting can be dangerous. Talk to a doctor before changing your routine in any way. If you feel dizzy, nauseous or very hungry, end the fast and eat.
Be careful with intense exercise too. If you train a lot, you need enough energy and protein. Try timing your workout within your eating window or right after it.
How to keep track of your fast without stress
The biggest problem is often not hunger but forgetting. If you only keep the edges of your window in your head, they blur easily. It helps to see your fasting time in front of you and to have a reminder.
In Caloora you set up an intermittent fasting schedule, the app shows a live timer and alerts you when your window opens or closes. You log food and water in the same place, so you can see whether you're reaching your daily calorie goal and macros within your eating window.
Your eating window is also a good chance to think about what's on your plate. Enough protein and vegetables in every meal will help you last until the next one. You'll find ideas in the articles High-protein breakfasts and Healthy lunches under 600 kcal.
Caloora shows you when your window opens and reminds you to drink. Free to start.
Try Caloora freeFrequently asked questions
Will I lose weight faster with intermittent fasting?
Not necessarily. Weight loss depends mainly on your total calorie intake compared with what you burn. Fasting can help you eat less if it suits you, but on its own it guarantees nothing.
What can I drink during a fast?
Water, unsweetened tea and black coffee. Anything with calories, such as sweetened drinks, juices or milk in coffee, breaks the fast. Getting enough fluids matters during a fast too, because if you don't drink enough, tiredness or a headache can show up easily.
Is it better to start with 16:8 or 12:12?
For beginners, 12:12 or 14:10 is a better fit. Your body adjusts gradually and the fast is easier to stick to. You can move to 16:8 once the shorter fast is no problem.
Can I exercise while fasting?
Most people can manage light movement, such as walking or a gentle workout. For intense training, it's better to plan it within your eating window. If you feel dizzy or weak, stop exercising and eat.
Who shouldn't do intermittent fasting?
It isn't meant for pregnant or breastfeeding women, minors, people who have had an eating disorder, people who are underweight or people with diabetes who take medication. If you have any medical condition, talk to a doctor first.
The information on this page is general and educational. It does not replace advice from a doctor, dietitian or trainer. If you have a health condition, take medication, or are pregnant or breastfeeding, talk to a professional before changing your diet or exercise.