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The beginner's guide to the 5:2 diet

Der Anfänger Ratgeber zur 5:2 Diät

Intermittent fasting is a dietary regimen that involves regular fasting. The 5:2 diet, also known as "The Fast Diet", is currently one of the most popular intermittent fasting approaches.

The 5:2 diet was popularized by Michael Mosley. It is called the 5:2 diet because you eat normally 5 days a week while restricting your calorie intake to 500 to 600 kcal per day on the remaining two days.

As there are no restrictions or requirements on the foods you can eat, the 5:2 diet is more of a lifestyle than a diet. Many people find this type of diet easier to follow than a calorie-restricted diet (1).

How does the 5:2 diet work?

The 5:2 diet is quite easy to explain. You eat normally five days a week and don't have to think about restricting calories. On the other two days, you reduce your calorie intake to around a quarter of your daily calorie requirement. This corresponds to about 500 kcal for women and 600 kcal for men.

You are free to choose which two days you prefer, as long as there is at least one non-fasting day between these two days. A common way to plan the week is to fast on Monday and Thursday with two or three small meals and eat normally on the remaining days of the week.

It is important to emphasize that "normal" eating does not mean that you can eat anything you want. If you stuff your stomach with junk food, you probably won't lose weight and could even gain weight. Rather, you should eat the same amount of calories as you would if you weren't fasting.

Summary: The 5:2 diet involves eating a normal diet five days a week and restricting your calorie intake to 500-600 kcal on the other two days.

Health benefits of intermittent fasting

There are few studies that have specifically investigated the health benefits of the 5:2 diet. However, there are plenty of studies on intermittent fasting in general that show impressive health benefits (2, 3).

One important benefit is that intermittent fasting appears to be easier for many people to adhere to than continuous calorie restriction (4, 5). Many studies have also shown that different types of intermittent fasting can significantly reduce insulin levels (2, 6, 7).

One study showed that the 5:2 diet caused weight loss comparable to that of regular calorie restriction. In addition, this diet was effective in reducing insulin levels and improving insulin sensitivity (8).

Several studies have examined the effects of modified fasting on alternate days, which is very similar to the 5:2 diet (which is ultimately a 4:3 diet) (9). The 4:3 diet can help reduce insulin resistance and provide relief for asthma, allergies, cardiac arrhythmias, menopausal hot flashes and many other conditions (10, 11).

A randomized controlled trial conducted with normal weight and overweight individuals showed significant improvements in the 4:3 group compared to the control group, which ate a normal diet (12).

After 12 weeks, the fasting group had

  • Reduced their body weight by 5 kilos
  • Reduced their fat mass by 3.5 kilos with no change in muscle mass
  • Reduced their blood triglyceride levels by 20%
  • Increased your LDL particle size, which is a good thing
  • Reduced your CRP levels, which is a marker for inflammation
  • Reduced your leptin levels by up to 40%

Summary: The 5:2 diet can have numerous impressive health benefits including weight loss, reduced insulin resistance and reduced inflammation, as well as improving blood lipid levels.

The 5:2 diet for weight loss

If you need to lose weight, the 5:2 diet can be very effective if followed correctly. This is mainly due to the fact that the 5:2 eating pattern helps you to consume fewer calories. It is therefore very important to make sure that you do not compensate for the fasting days by eating more on the remaining days.

Intermittent fasting does not cause greater weight loss than regular calorie restriction if the calorie intake is the same (13, 14). Fasting protocols similar to the 5:2 diet have shown promise in weight loss studies:

  • One study review concluded that fasting on alternate days resulted in weight loss of 3 to 8% over the course of 3 to 24 weeks (15).
  • In the same review, subjects lost 4 to 7% of their waist circumference, which means they lost a lot of harmful belly fat.
  • Intermittent fasting causes less reduction in muscle mass compared to conventional calorie restriction (15, 16).

Intermittent fasting is even more effective when combined with exercise such as endurance training or strength training (17).

Summary: The 5:2 diet is very effective for weight loss when followed correctly. It can help reduce harmful belly fat and maintain existing muscle mass during weight loss.

How you should eat on fasting days

There are no set rules about what or when to eat on fasting days. Some people work best if they start the day with a small breakfast, while others find it best to eat as late as possible.

In general, there are two primary meal patterns that are used:

  • Three small meals: usually breakfast, lunch and dinner
  • Two slightly larger meals: Lunch and dinner only.

Since calorie intake is limited - 500 kcal for women and 600 kcal for men - it makes sense to use your calorie budget wisely. Try to focus on nutritious, high-fiber and high-protein foods that will fill you up without providing too many calories.

Soups are an excellent option for fasting days. Studies have shown that they fill you up better than the same ingredients in their original form or other foods with the same calorie content (18, 19).

Here are a few examples of foods that work well for fasting days:

  • A generous portion of vegetables
  • Natural yoghurt with berries
  • Boiled or fried eggs
  • Grilled fish or lean meat
  • Cauliflower rice
  • Soups (e.g. miso soup, tomato soup or vegetable soup)
  • Black coffee
  • tea
  • Still or sparkling water

There is no specific correct way to eat on fasting days. You will have to experiment to find out what works best for you.

What can you do if you feel unwell or experience uncontrollable hunger?

During the first few days of the 5:2 diet, you may experience episodes of overwhelming hunger. It's also normal to feel a little weaker or slower than normal. However, you may be surprised at how quickly the hunger disappears, especially if you try to keep busy or otherwise distract yourself.

In addition to this, most people find that fasting days get easier after the first few days of fasting. If you are not used to fasting, then it may be a good idea to have a snack on hand during the first few days of fasting in case you feel dizzy or nauseous.

However, if you repeatedly feel unwell or dizzy during the fasting days, you should discuss with your doctor whether or not you should continue with the 5:2 diet.

Intermittent fasting is not suitable for everyone and some people are not able to cope with it.

Summary: It is normal to feel hungry and a little weaker than normal during the first few days of fasting. If you repeatedly feel unwell or dizzy, you should discuss continuing the 5:2 diet with your doctor.

Who should avoid the 5:2 diet or intermittent fasting?

Although intermittent fasting is very safe for healthy, well-nourished people, it is not suitable for everyone. Some people should avoid dietary restrictions and fasting completely. These people include:

  • People with a history of eating disorders
  • People who frequently experience a drop in blood sugar levels
  • Pregnant women, breastfeeding mothers, teenagers, children and people suffering from type 1 diabetes
  • Women who want to get pregnant or have fertility problems

In addition, intermittent fasting may not be as beneficial for women as it is for men (20, 21). Some women have reported that their menstrual periods stopped while following this type of dietary regimen. However, this returned to normal after they switched to a normal diet.

For this reason, women should be careful when doing any form of intermittent fasting and stop immediately if any unwanted side effects occur.


The 5:2 diet is a simple, effective way to lose weight and improve metabolic health. Many people find it much easier to follow this diet instead of a calorie-restricted diet.

If you want to lose weight or improve your health, then the 5:2 diet is definitely something you should consider.




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