Intermittent Fasting: What It Does and How to Get Started

10 November 2026 5 min read

Intermittent fasting, also called intermittent energy restriction, is one of the most popular ways of eating in recent years. Instead of counting calories or banning foods, you decide when you eat. Between meals there are deliberately longer breaks, during which you consume nothing or only calorie-free drinks.

This sounds simple, and for many people that is exactly why it fits into everyday life. At the same time, many promises surround fasting. In this article we take a sober look: what intermittent fasting can do, what it cannot do, and how you can sensibly combine it with your training.

First of all: if you have an illness, take medication, are pregnant or have had an eating disorder, get it checked by a doctor before you start fasting.

The most important methods of intermittent fasting

There is not one single form of intermittent fasting, but several models. Which one suits you depends mainly on your daily routine.

16:8: You eat within an eight-hour window and fast for 16 hours, for example eating between 11 a.m. and 7 p.m. By far the best-known variant, because a large part of the fasting period falls during the night.
14:10: The gentler form with a ten-hour eating window. Ideal for getting started.
5:2: You eat normally on five days and reduce your intake sharply on two non-consecutive days.
Eat-Stop-Eat: You fast for 24 hours once or twice a week. This method is demanding and better suited to experienced people.

For most people, 14:10 or 16:8 is the most realistic approach, because the method fits well with work, family and training.

Does intermittent fasting help with weight loss?

Yes, but not because of some secret metabolic trick. The main reason is simple: if you have less time to eat, you often automatically eat less. What remains decisive for weight loss is the calorie deficit. If you eat more than you burn within your eating window, you will not lose weight despite fasting.

The benefit therefore lies mainly in structure. Many people snack less, eat more mindfully and have fewer spontaneous intense hunger pangs in the evening. If you want to lose belly fat in particular, our article on losing belly fat explains further why exercise and nutrition belong together.

What intermittent fasting cannot do

It does not replace a balanced diet. Fast food within your eating window is still fast food.
It does not guarantee muscle gain, quite the opposite if you eat too little protein.
It is not suitable for everyone. If you sleep poorly while fasting, feel irritable or constantly think about food, you should choose a different strategy.

Combining intermittent fasting and training

Many people wonder whether they may train on an empty stomach. For moderate endurance training or light strength training this is usually unproblematic for healthy people. For intense sessions, however, you often lack performance without energy.

A few principles can help you:

Schedule your training within your eating window or shortly before it. That way you can plan a meal directly afterwards.
Make sure you get enough protein. Spread it across two to three meals within your eating window. You will find inspiration in our overview of high-protein foods.
Drink enough. Water, unsweetened tea and black coffee are allowed during the fasting phase.
Plan intense sessions wisely. A HIIT workout or a heavy leg session usually feels better after a meal than after 16 hours without food.
Listen to warning signs. Dizziness, shaking or strong fatigue are clear signals to stop training and eat something.

How to build your meals around training is explained in our article on nutrition before and after exercise.

How to start intermittent fasting: a simple plan

You do not have to fast for 16 hours from one day to the next. A gradual start is more pleasant and increases the chance that you stick with it.

Week 1: Skip snacks after dinner. This alone often already gives you twelve hours of fasting overnight.
Week 2: Move breakfast back by an hour or eat dinner a little earlier. Goal: a 13 to 14 hour break.
Week 3: Test the 16:8 model on three to four days. Observe how you feel, how you sleep and how your training goes.
Week 4: Decide which window works for you in the long term. It does not have to be the same every day, for example a relaxed weekend.

What belongs in your meals?

A portion of protein in every meal, for example eggs, yoghurt, legumes, fish or meat
Plenty of vegetables and fruit for fibre and micronutrients
Wholegrain products or potatoes as an energy source, especially on training days
Healthy fats from nuts, seeds and olive oil

Frequently asked questions

May I drink coffee during the fasting period?

Yes, black coffee without milk and sugar practically does not break your fast. Milk, sugar or syrup, on the other hand, provide energy and belong within your eating window.

Will I lose muscle with intermittent fasting?

Not if you eat enough protein and do strength training regularly. A large deficit without training can, however, also cost you muscle mass.

Is intermittent fasting healthier than other diets?

For weight loss, it is mainly a matter of personal preference. The best method is the one you can keep up in the long term and that is good for you.

Conclusion: intermittent fasting as a tool, not a miracle cure

Intermittent fasting can help you structure your eating, snack less and keep a calorie deficit more easily. The basics remain the same, however: balanced meals, enough protein, sufficient sleep and regular exercise.

Would you like to know how nutrition and training can work best together for you? At update Fitness, our free coaching by trained coaches supports you, and with update Nutrition you get additional impulses for your diet.