top of page

Intermittent Fasting: What, Why, How, Who?


With intermittent fasting, you restrict your calorie intake for a period of time and then go back to your normal eating habits.

There are several methods to do the intermittent fasting, and the most popular ones are:

-The 5:2 Method: you fast for 2 days of the week (you reduce your daily calorie intake to 500 for women and 600 for men), and eat normally for the remaining 5 days.

-The 6:1, same as above but you fast only once a week

-Alternate Day Fasting (ADF), where you restrict your calorie intake to 500-600 every other day

-16:8 You eat during 8 hours of the day and fast for 16 hours

In this article, we will focus on the 5:2 diet as it is the most popular one.


The science behind the diet

Why fast? Because our bodies are programmed to hunt, find food, eat and fast until food is available again.

Dr. Michael Mosley has created the 5:2 diet and describes it as "a little poison is good for you." When you fast, your body is in pseudo-shock and regenerates itself. A lot of research has been done on this subject and was conducted on either a small number of humans or on animals. More data is needed but what we currently know is that this diet:

-Helps you lose weight (on average 3.6kg after 3 months or 7.7 in 6 months) and does not decrease your metabolism

-Improves sugar and cholesterol levels

-Helps gene repair and stem cell regeneration

-Improves response to chemotherapy

-Enhances the mood

You can find more details and references in the Fast Diet book (Written by Mosley and Spencer).


1. Choose your 2 days of fasting. To make it easier, select non-consecutive days where you are busy and won't be thinking of food all day.

2. When you eat is important. Your body (especially the liver) needs to rest. Do not spread the food throughout the day. You should ideally have breakfast and diner only.

3.Prepare the food in advance; there is nothing more tempting than looking for food when you are hungry. Recipe ideas can be found online. A useful website is BBC's good food but many other exist.

4.You can have replacement food (such as shakes) if it makes calorie counting easier.

5.Increase your amount of fluids you drink to 2-3L/day (water, non-sugary tea or infusions, occasional black coffee) to compensate for the fluid you are missing from food.

6. If you want to lose weight: do not overeat on non-fasting days (2000kCal for women and 2400kCal for men).

7.If you do not want to lose weight (you are following this diet for other health benefits): increase your calorie intake on the other days. The 6:1 diet could be a more suited option for you.


In his book, Dr. Mosley recommends you get checked by your doctor before starting the diet as it is not suited for everyone (e.g. pregnant and breastfeeding women).


Discuss with your healthcare professional before starting a fasting diet



2.Mosley, M., and Spencer, M. (2014). The Fast Diet (Short Books).


More articles

Subscribe to Our Newsletter

Thanks for submitting!

bottom of page