What happens to your body when you fast?

Apr 4. 2021

An overnight fast of 8-10 hours is normal for most people. Periods of deliberated fasting with restricted food intake is also practiced worldwide, mostly based on tradition or religious reasons. Some examples of deliberate fasting include alternate day fasting, time restricted feeding, and the 5:2 diet.

There are many beneficial effects of fasting that are supported by observational studies. These found that food caloric restriction and intermittent fasting is associated with deceleration or prevention of most chronic inflammatory diseases such as metabolic diseases, pain syndromes, andatopic and psychosomatic disorders. There are some results regarding the role of fasting for weight loss and maintenance loss. Epidemiology says that in humans, grazing throughout the day, increased the odds of having obesity by 57 %. Every three hours increase in the daily duration of eating increases the risk of pre diabetes and diabetes by 20%. The American Heart Association, in regards to the frequency and timing of meals in preventing cardiovascular disease, states that intermittent fasting can be used as a strategy for weight loss, and eating more calories during the day and overnight fasting is a practice recommended for most individuals.

Some benefits of fasting are:

  • Greater weight loss
  • Greater fat mobilization
  • Slower cell proliferation
  • Lower inflammation and oxidative stress
  • Improved lipid profile and blood pressure
  • Slower aging
  • Increased HGH and athletic performance

It is well known that fasting changes the circadian rhythm of hormones including cortisol, growth hormone and sex hormones. Experimental fasting shows significant changes in cognitive function, sleep and wakefulness patterns. Some studies reported a reduction of REM sleep and significant delays in bedtime and wake time with fasting. No changes were observed in working memory and spatial orientation ability, while fasting increased anger in the first days and euphoria later.

During the Covid 19 pandemic, concern about immunity is growing and some studies have shown that fasting for at least 3 days allows the body to start producing new white blood cells, which rejuvenates the immune system to fight infection. However, other studies with humans and animals have demonstrated  that the number of white blood cells decreases with long-term fasting and blood cells return when they are re-fed. In order to ensure the success, adherence and monitoring of health outcomes, it is recommended that all interventions during the fast are guided by trained staff.

GluCare introduces another element into intermittent fasting. By the addition of Digital Therapeutics (DTx) we are able to help you monitor the short and long term effects of intermittent fasting for maximum effectiveness. Using the GluCare DTx program, our clinical team, partnered with you, can monitor your blood glucose, weight, and activity levels on a daily basis. We can show you how fasting affects you personally, and assist you in balancing your activity, diet, and logging your food to increase your level of short, and long term success in lifestyle changes.


  • Integrative Physiology of Fasting . Compr Physiol .2016
  • Fasting Therapy for treating and preventing disease- Forsch Komplementmed.2013.
  • Energy Metabolism and Intermittent Fasting . Nutrients 2019.
  • Abeso – n. 87 . 2017
  • Ramadan Fasting During the COVID-19 Pandemic; Observance of Health, Nutrition and Exercise Criteria for Improving the Immune System. Front nutri 2020

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