To Eat or Not to Eat? An Overview of Intermittent Fasting

Salad with meat

Diets are a dime a dozen, so it’s easy to lose sight of the important questions like how does the diet work, or what are the benefits and risks associated with it? The latest nutrition trend is intermittent fasting (also called interval eating). This type of diet is very popular among athletes, but people who want to lose weight also tout it as the ultimate slim-down method. How does it work? And can intermittent fasting be dangerous? 

Check out the answers to the most burning questions on interval eating as well as helpful tips: 

 woman in the kitchen preparing food

What is intermittent fasting?

As the name suggests, intermittent fasting is an approach to nutrition that cycles between periods of fasting and eating. Strictly speaking, interval eating is not a diet but more of an “meal schedule.” You are not told what to eat, but you do have to stick to specific times. 

There are several methods of intermittent fasting. The most popular ones are:

  • 16/8 method: This is known as the Leangains method. Here, you have a feeding window of eight hours and a fasting period of 16 hours. Put simply, the normal fasting period while you sleep is simply extended by a few hours. You can skip breakfast, for instance, and consume your first meal at noon and keep eating up to eight o’clock in the evening.
  • 5:2 diet: The idea is that for two days a week you reduce your calorie intake to a maximum of 500 to 600 calories per day. The days do not have to be back-to-back. The other five days you can eat what you want within reason.
  • Eat Stop Eat: This type of intermittent fasting alternates between fasting and non-fasting days. You eat what you want for 24 hours and then take a complete break from food on the following day. You repeat this pattern once or twice a week. Calorie-free beverages (such as black coffee, unsweetened tea, etc.) are allowed, as they are in the other  intermittent fasting methods as well.

How does interval eating affect your body? 

Intermittent fasting does far more than just restrict your calorie intake. It also changes the hormones in your body so they can make better use of your fat stores. The following changes take place:

  • Intermittent fasting improves your insulin sensitivity, especially in combination with exercise. This is very important for people struggling with their weight because low insulin levels in the blood are associated with better fat burning. The opposite of this is insulin resistance. Studies have shown that increased body weight can interfere with insulin’s ability to reduce blood sugar levels, resulting in more insulin being released. This in turn promotes the storage of fat.
  • The secretion of human growth hormone (HGH) increases, speeding up protein synthesis and making fat available as an energy source. This means, in simple terms, that you burn fat and pack on muscle faster. This is why HGH is often taken in large quantities by the bodybuilding community as a doping agent.

Furthermore, according to research, fasting activates autophagy, which removes damaged cells, contributes to cell renewal and generally supports your body’s regenerative processes.

big bowl of salad

How do you lose weight with intermittent fasting? 

If you skip meals and create a calorie deficit, you will lose weight. That is, unless you compensate for the fasting periods with foods that are packed with fat and sugar. It can happen: This type of eating pattern does not necessarily tell you what foods you should or shouldn’t eat. Studies have found that intermittent fasting (if done properly) can be just as effective at preventing Type 2 diabetes as a daily reduction in calories.(1) Plus, your body can learn to process the foods consumed during the “eating window” better and more efficiently.

A study on intermittent fasting has shown that a combination of the 16/8 method and strength training (with your own body weight, as well as free weights) can reduce more body fat than strength training alone.(2) However, there was no sign of muscle growth in the subjects included in the study.

Note: This type of dieting is not necessarily suitable for people with diabetes, high blood pressure or pregnant & breastfeeding women. You should check with your doctor before changing your eating pattern.

Fasting and exercise – how to combine the two

There are a couple of points to pay attention to when combining fasting (e.g. intermittent fasting) and exercise: 

  1. If you are trying to lose weight, it is very important that your calorie reduction is moderate and you aim for only 0.5-1% of body weight lost per week. 
  2. Include strength training sessions and a lot of protein in your diet to preserve lean muscle mass (about 20% or more of your total energy intake should be protein).(3)
  3. Try to time your workouts right before the largest meal of your day. If you plan on combining intense workouts and fasting, it’s best to consult both a nutritionist and an exercise professional.

Who shouldn’t try interval eating?

If you are in good health, there’s no reason why not to try intermittent fasting. Some people should be careful with this kind of diet, though, and consult a doctor before starting it. 

People with the following conditions should steer clear of intermittent fasting:

  • Diabetes and other metabolic disorders
  • Cardiovascular disease
  • Cancer

Intermittent fasting is also not appropriate for:

  • Children
  • Pregnant women
  • Breast-feeding women
  • Anyone with a history of an eating disorder
  • Elderly people

What is the impact of interval eating on your social life? 

Fasting can be an effective way to lose weight, but have you ever considered the social aspect?

Picture this: Friends have invited you to a birthday brunch on Sunday. The breakfast buffet is replete with delicious muesli, fresh fruit, yogurt, scrambled eggs, vegetables, salmon…  Your friends dig right into their sumptuous breakfast. And you? You sit next to them and sip on your water. After all, it is only ten o’clock in the morning and you can’t eat your first meal until noon. Plus, you have dinner plans that same evening at 7 pm – with an eight-hour window, you have to make the most of it. If you plan your fasting window cleverly, you can still enjoy meals together with your friends and family.

Intermittent fasting is definitely not for everyone, but it can be a good method for reducing body fat. Generally speaking, interval eating doesn’t leave much room for flexibility and spontaneity. So if that is important to you, you might be better off looking for another diet approach, such as IIFYM (if it fits your macros), which is a flexible diet in which you can eat anything, as long as you stay within the parameters of your defined macronutrient goals.

people eating together

What can you do when hunger strikes?

Many people who try intermittent fasting complain about sharp hunger pains, fatigue, exhaustion and cravings, which makes sense considering that you skip meals. But others say that the hunger goes away once you have withstood the first “critical” phase (about two days). If your hunger gets too bad in between, you can try drinking some green tea or black coffee to help you get by until your next meal.

Intermittent Fasting: 8 Tips to Get Started

Keep the following things in mind if you want to try intermittent fasting: 

  1. Don’t overdo it with portion size during the “eating window”.
  2. Make sure you eat a balanced, healthy diet. Eat foods rich in fiber to keep you full (fruit, vegetables, legumes, whole-grain products), high quality sources of protein (fish, soy, eggs, dairy products, legumes) and fat (vegetable oils, nuts, seeds, avocado).
  3. Drink plenty of water or unsweetened tea. Use this calculator to figure out about your liquid requirements.
  4. It might take some time for your body to adjust to the breaks in your eating schedule. You have to be patient if you want to stick with interval eating. If you’re really hungry, drink a cup of green tea or black coffee to quiet your growling stomach.
  5. Do regular strength training and eat a diet rich in protein to avoid losing muscle mass.
  6. No matter when you work out, the biggest meal of the day should be after your workout.
  7. A lack of sleep can lead to weight gain. Always try to get a good sleep. 
  8. Intermittent fasting is not for everyone. If you’re not sure about it, check with your doctor (see above).

Bottom line:

Intermittent fasting or interval eating is not right for everyone, but it can be helpful if you want to lose weight. Keep in mind, it may be just as effective to cut your daily calorie intake. You should definitely watch what foods you eat during the eating window; don’t just stuff yourself with burgers, fries and pizza. The focus here, as elsewhere, should be on eating a healthy, balanced diet.

For info about a variety of other diet types, check out this expert overview to get the facts.



Julia Denner As a dietitian, Julia wants to inspire others to eat a healthy and balanced diet. She loves cooking, being outdoors, and does yoga and strength training to relax. View all posts by Julia Denner »