Experts reveal what happens when you fast for 36 hours

Fasting is currently one of the biggest health trends across the globe with many people engaging in intermittent or longer term fasts. These practices come with some amazing health benefits and fitness experts at have broken down how to fast and why you should try it!


How to fast

  • Fasting is simply not eating for a prolonged period so that your body utilises other sources of energy. The idea is that your body will start to burn fat in the absence of food, and you remain in a calorie deficit to further aid fat loss.
  • During a fast, 0-calorie drinks are permitted, such as black coffee and tea; however, the best advice is to stick to just drinking water while fasting; it is pivotal to avoid dehydration during fasts.
  • When breaking a fast, you may be tempted to have a larger-than-normal meal, this can lead to tiredness and feeling bloated. It’s recommended to stick to normal eating habits and portion sizes once a fast is broken.
  • Outside of your fast, it’s important to still eat a healthy diet, as eating excessively or eating highly processed foods will mean you may not see any results from your fast.
  • To optimise your fast, a high-protein diet can make you feel fuller and less likely to overeat while aiding in fat loss, muscle growth, and muscle maintenance.

If you are thinking of fasting, it’s advisable to start with a short fast and work your way up to longer fasts.


Types of fast

There are a plethora of ways to fast; 16/8 intermittent fasting is one of the most popular forms in which you eat in an eight-hour window and then fast for 16 hours. Many people choose to eat between midday and eight o’clock. This can help some people with cravings as they will sleep throughout much of the fasting period.

Eat stop Eat is another popular type of intermittent fast, this is when a 24-hour fast is completed once or twice weekly. This can help lower your weekly calorie, meaning that the occasional treat at the weekend won’t impact your health and fitness goals.

Many people, such as our Prime Minister, choose to fast for 24 – 72 hours, either weekly or monthly. These longer fasts have many health benefits beyond just weight loss and may seem daunting at first, but if you have worked your way up through intermittent fasts, it may not be as bad as you think.



What happens to your body? Benefits of fasting:

Over the course of a fast, many things happen to your body that will have amazing impacts on your health. Research has shown that the many benefits of fasting include lower insulin levels, enhanced recovery, reduced inflammation, boosted metabolism, increased fat burning and cellular regeneration (this helps decrease the risk of cancer and neurodegenerative disorders).


12 hours


All food in the digestive tract is now burned, and around hour 13, autophagy may start; this is a cellular renewal process where damaged and dysfunctional cells are removed. This helps your body fight disease, viruses, harmful bacteria and combat cancer. Human Growth Hormone begins to increase. HGH supports metabolism and improves muscle growth, strength, and lean body mass. Low HGH levels may decrease your quality of life, increase your risk of disease, and lead to body fat gain.

Between 16 – 23 hours, your body is burning your fat stores to keep up with your energy demands because you don’t have any glucose left this begins the fat burning process.


24 Hours


At 24 hours, glucose is used up. Ketosis takes control; this starts when insulin levels drop, and your body turns stored fatty acids into energy molecules called ketones. This speeds up the fat-loss process.


36 Hours


Autophagy increases by 300%. Your body is in a complete clean-up mode, shedding the dead and damaged cells. Fat loss continues throughout this whole process. Participating in light workouts can also speed up these processes.

After 36 hours, the body further increases the rate of autophagy and ketosis, HGH also increases by about 500%. After 72 hours, these begin to plateau, which is why most people stick to a maximum of 72 hours. The effects of muscle loss also don’t begin until after 72 hours in most people, so there’s no need to worry about losing your hard-earned gains while fasting. Before making any major changes, it’s always worth consulting your GP.

A spokesperson from commented: “Fasting is more than just skipping meals; it’s a journey of self-discovery. By choosing to abstain from food, we unlock hidden strengths within ourselves. It’s a cleansing process for both the body and soul, providing a space for reflection and inner growth.

These practices have boomed in popularity in recent years, and many have seen the incredible effects that they can have on the body and mind. Fasts can be adapted to each person to work around your schedule and eating habits, making them a great choice to begin your health journey.”