Intermittent fasting and chronic illness: Everything you need to know!

Published 3 Mar 2020 • By Camille Dauvergne

"Fasting" means voluntarily depriving oneself of food. It is an ancestral practice often carried out for religious or spiritual reasons, but also for therapeutic purposes. It is even becoming a fad! We're breaking down this new regimen to help you understand it better.

Intermittent fasting and chronic illness: Everything you need to know!

What is intermittent fasting?

Fasting means voluntarily depriving oneself of food. It is an ancestral practice often carried out for religious or spiritual reasons, but also for therapeutic purposes. It is even becoming a fad!

Intermittent fasting involves reducing one's food intake window, or eating as much as one normally does but over a shorter period of time. In other words, it includes eliminating either breakfast or dinner and eating the equivalent of the skipped meal during the rest of the day. Intermittent fasting can also entail reducing one's caloric intake, including full-fast days and "normal" days.

Intermittent fasting must therefore be distinguished from complete fasting (zero calorie intake) and continuous partial fasting (continuous restriction of calorie intake). This type of fasting can be practised by a healthy person (more for preventative purposes) or by a sick person (more for a curative/therapeutic purposes).

Different types of intermittent fasting

We can distinguish several types of intermittent fasts, such as:

  • The 16/8 method: which involves fasting for 16 hours out of 24, something which is much more common than we think, as many people skip breakfast!

  • The 5:2 method: where one consumes 500 calories per day, on two non-consecutive days per week.

These two methods are intended for occasional practice - by individuals who are not used to skipping meals - to rest the digestive system.

  • Fasting every other day, or 1 day once or twice a week.

  • Therapeutic fasting (sanogenesis): a method that must be supervised by a physician and practised for therapeutic reasons (cancer, chronic inflammatory illnesses, etc.).

  • Fasting when you want/can: depending on how hungry you feel, this is the most intuitive method.

Benefits of intermittent fasting

Intermittent fasting appears to have an effect on circadian rhythm, gut biome, and caloric restriction. Regarding its effect on the gut biome, this regimen seems to reduce the discomfort associated with problems of intestinal permeability and inflammation often present in obese persons, in particular.

Many people observe weight loss following their intermittent fasting regime because, if it is well practised, the metabolism adapts to food restriction by drawing from lipid stores once food reserves have been exhausted.

Other beneficial effects can be noted, such as a decrease in hunger, improved sleep, or an increase in vitality and concentration.

Is it clinically approved?

9 interventional studies studying the effect of intermittent fasting over several months in overweight or obese patients have been conducted. Of these, 7 confirmed weight loss and about half showed an improvement in metabolic markers. However, metabolic markers were not always improved in the various studies. There is fairly clear evidence that intermittent fasting is more beneficial than total abstinence from food and some restrictive diets. Scientific studies conducted in mice have shown good results on increased lifespan, resistance to oxidative stress, and toxicity with chemotherapy.

Caution! It is important to note that studies on intermittent fasting are not always of high quality or are well-controlled, and often show limited evidence.

For which diseases is it recommended?

Intermittent fasting could improve symptoms in Irritable Bowel Syndrome, improve pain and morning stiffness in rheumatoid arthritis, significantly reduce pain in chronic pain conditions such as fibromyalgia. In metabolic syndromes such as diabetes, metabolic fasting could increase insulin sensitivity, stimulate lipolysis and lower blood pressure. It could also improve the signs of atopic dermatitis.

Fasting for cancer

Fasting (generally speaking) is under development in oncology: it could improve the impact of cancer cell treatments, protect healthy cells, reduce the side effects of chemotherapy such as nausea/vomiting, diarrhea and abdominal cramps, and rebuild the immune and hematopoietic (which forms cellular blood components) systems more quickly.

Fasting for cardiovascular disease

Improvements in lipid metabolism, inflammatory markers, and high blood pressure have been observed, and decrease in weight and in blood glucose parameters have been noted.

Other diets such as the Fast Mimicking diet may be recommended in Crohn's disease cases. This diet involves consuming plant-base, whole-food derived prepackaged meal kits which are low in calories (restricting daily calorie intake) and rich in good fats for 5 days.

However, there is no scientifically substantiated and proven conclusion to validate these medical indications. In chronically ill patients, it is vital to seek medical advice before starting an intermittent fast, which must be accompanied by appropriate medical supervision, in a fasting clinic, for example.

For whom is it contraindicated?

Intermittent fasting is contraindicated in children, pregnant or breastfeeding women, the elderly, and those at risk of hypoglycemia or with hormonal imbalances..

Some advice before starting intermittent fasting

  • Stay hydrated by drinking a minimum of 2 to 2.5 litres of water per day.
  • Maintain adequate protein intakes (around 1.2 g of protein/kg/day).
  • Consume high-quality fats, especially vegetable fats, between fasting periods.

If you don't know what type of fasting is right for you or how to go about it, it is best to consult a healthcare professional before beginning a fast.


Do you practice intermittent fasting? Have you noticed an improvement in your health?

Warning: This article is a general overview and does not replace medical advice given by a healthcare professional. It does not take into account individual patient cases which may vary. Each patient is different, always talk to your physician before beginning or altering your treatment!

avatar Camille Dauvergne

Author: Camille Dauvergne, Junior Community Manager France

Camille Dauvergne is currently a Junior Community Manager at Carenity. She assists the France Community Manager in animating the platform, easing member navigation of the site and encouraging them to interact.... >> Learn more


on 10/03/2020

An interesting read. Thank you. It backs up how I feel (better/lighter/more energised) on days when I miss (skip) a meal (usually because I am busy). So it is good to see some more scientific thought on the benefits (rather than being co-incidental). 

robjmckinney • Ambassador
on 10/03/2020

Fasting for cancer is a death sentence as losing weight during treatment is very much the norm. I lost six stone during my cancer treatment. If you lose more than 10% of your body weight during treatment our hospital policy was to take you in as a inpatient and feed through a tube. A young American airman and myself went through cancer treatment, he was in hospital quickly but myself being overweight never had to go in, despite losing more than 10% of my bodyweight. So if you are going through cancer treatment put some weight on before you go in as you lose weight massively during treatment. Putting weight on after treatment is difficult because you just can't eat so don't diet and find suitable foods you can keep down. I lost so much weight as a type two diabetic, I was injecting before treatment and lost so much weight I changed to diet only treatment for my diabetes. Don't diet or fast before cancer treatment unless you like hospital being fed through a tube. Plus having a little extra weight is a real plus for survival after operations, Surgeons and staff all noted that having a little extra weight increases your survival! 

on 11/03/2020

I have fibromyalgia and Crohns. Lucky me! But all my symptoms have improved since doing the 16/8 fast. I have been doing it for about 6 months and can’t recommend it more highly. Worth a try for anyone with health issues as it is so easy and the side effect for this overweight lady is weight loss too.

on 14/04/2020

I have psoriatic arthritis, fibromyalgia, IBS, high blood pressure,and cfs, intermittent fasting has helped a lot especially with my IBS. I do the 16/8 regime.

on 13/09/2021

I have found it a tremendous boost to brain power amongst loads of other benefits, weight loss, feel fitter and can walk easily 5 miles  a day now. Skin improved, blood pressure down to normal no diabetic meds need anymore, for me a whole new ball game. I have psoriatic arthritis, diabetes, COPD, hypothyroidism and CKD and am 65 yrs old and in last two years following low carb and 24 hr intermittent fasting I have gone from a dress size 24 to a size 12 and feel ten years younger and fitter. For me I cannot recommend it highly enough, I feel it saved my life

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