Four Types of Fasting and Their Characteristics

There are at least four types of fasting, depending on their characteristics. Some are short and healthy, while others are long and unhealthy. Continue reading to find out more about them!
Four Types of Fasting and Their Characteristics

Last update: 03 January, 2021

There are four types of fasting. Some can have a positive impact on your health, while others do just the opposite.

The main advantage of these eating protocols is the caloric restriction. This is because it’s easier to be in control of your weight. Also, they produce a series of hormonal changes that aid in the prevention of many chronic diseases, such as diabetes.

Types of fasting and their characteristics

Fasts can be classified as either short or long in the first instance.

Short ones last less than three days. These don’t usually lead to complications and there’s nearly zero health risk for the healthy population who don’t require medical supervision or supplementation. Furthermore, there’s evidence of its effectiveness when it comes to losing weight and preventing metabolic conditions.

However, long fasts that extend over several days and even weeks, and are usually accompanied by strict monitoring to avoid dehydration, protein malnutrition, and hypovitaminosis.

1. Intermittent fasting

This is probably the most widespread. It consists of fasting for a few hours in a day, as stated in a study published in the Journal of Translational Medicine.

The ratio of the most common protocol is 16:8 (16 hours of fasting) and it’s common to skip breakfast in this type of situation. You can drink water, coffee, tea, or some other hot drinks during the fasting period.

Generally, it’s easier to skip breakfast than dinner due to the circadian cycles of the hormone ghrelin (appetite controller). Normally, the last intake of the day should be around 10 p.m. and the first one the following day around 2 o’clock at noon.

It’s a comfortable method that allows weight loss without being too hungry. Another positive thing about it is you can do it daily or weekly.

A plate decorated as a clock.
Intermittent fasting is widespread and recognized for its ability to assist in weight loss without going hungry.

2. 24-hour fasting

This is a slightly more aggressive method and thus harder to follow for those who aren’t used to this kind of thing. It consists of fasting one or two days per week. That is one day of fasting followed by either three or six days of regular eating, depending on the option you choose.

The disadvantage of this method is that it could lead to the loss of a certain amount of protein catabolism and muscle loss. Exercising while you do intermittent fasting can be good but doing it when you do a 24-hour fast becomes somewhat critical due to the lack of glycogen and nutrients at the muscle level.

These fasts significantly reduce the number of calories you take weekly. Thus, they’re quite effective when losing weight is the goal. They have certain limitations in people with complex diseases such as thyroid problems though.

3. Protein fasting

This is a modified version of intermittent fasting. It consists of fasting at a ratio of 16:8. The difference is the limited intake of some forms of protein is allowed.

As the main advantage of this method, we must emphasize that the protein catabolism is much lower than in the previous cases. It’s a good choice for those active people who are trying to define their muscles while maintaining their mass.

Similarly, the possibility of eating certain types of food during the fasting period reduces the appetite in people for whom the 16:8 fasting is difficult.

A no-eating plate.
Protein fasting allows a limited intake of food, so it’s a good option for active people who are trying to define their muscles.

4. Long fasting

Fasting for more than 3 days is a good choice for morbidly obese people and must always be supervised by a physician or medical professional. This is because they must administer solutions with intravenous glucose to those following these kinds of fasts.

Also, the supply of vitamins and minerals through supplements, and proper hydration, are essential. These fasts are effective but carry certain risks. Thus, medical supervision is required when adopting one.

These are delicate situations and you must evaluate the pros and cons well before starting this type of fast. The results in terms of weight loss are quite remarkable; however, the loss of lean mass is also significant.

Some of the four types of fasting are effective to lose weight

As you read above, there various types of fasting have many advantages in terms of improving body composition and preventing disease. Ideally, if you’d like to try fasting, it’s best to start with a simple protocol such as 16:8 and then you can explore the rest of the possibilities from there.

The combination of intermittent fasting and moderate-intensity exercise is ideal when burning fat is the goal. If you have any questions, make sure to ask a doctor or nutritionist. 

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  • Moro T., Tinsley G., Bianco A., Marcolin G., et al., Effects of eight weeks of time restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance trained males. J Transl Med, 2016. 14 (1):290.
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