What is intermittent fasting?

Intermittent fasting (IF) is not a diet. When you practise IF you interchange periods where you eat with those where you don't eat, thus you fast. Although it has many other benefits it is mainly used to lose weight.


Losing weight with IF may, for some people, be easier as there are no real food restrictions.


Let’s see what this way of eating is about and if it could be something for you to try.


Fasting has been shown since ancient time to have benefit our system. All around the world it has been used as a way to clean the body from toxins and other metabolic waste products. Though it comes with a challenge: you have to be quite disciplined. And apart from discipline, people are experiencing symptoms like weakness, headaches, shakiness and low blood pressure during fasting periods, which is why they stop it eventually.


IF combines the great benefits of fasting with periods where you are allowed to eat, so the above mentioned symptoms are less likely to occur. IF became popular in 2012 after the BBC series “Eat, fast and live longer”.


There are 4 different ways of practising IF:


16:8 method

The probably most popular way of practising IF. You can eat during 8 hours and then have to fast during the remaining 16 hours of the day. This means you either skip your breakfast if you rather prefer late dinner or the other way around if you can’t start the day without having breakfast.


36:12 method

With this principle, you fast every other day. On one day you can eat normally - from 8 in the morning until 8 in the evening. During the night and the whole next day you fast. The third morning you break the fast again.


20:4 method

The hardest version of all and probably only for a short time recommended. The time frame that allows you to eat is limited to 4 hours a day.


Whole fasting days

The concept is also used in the 5:2 diet. You practise two fasting days a week or at least the calorie amount you eat on the “fasting days” is very restricted.


Which types of food are allowed and which ones should be avoided:

One benefit of IF as a diet is, as already mentioned, that there are no general restrictions or foods that are forbidden. Each method recommends a healthy way of eating, high in fruits, vegetables, healthy grains and fat and low in sugar, processed foods and alcohol. But whatever you fancy every now and then is perfectly allowed.


IF passed the test of time. Many diets are forgotten as fast as they come up because they either don't bring results, are difficult or complicated to do, are expensive or just restrict people to much in living their daily life.


This is not the case with IF. It is as trendy as ever, being one of the three diet trends to follow in 2019 as well (besides the ketogenic diet and clean eating).  


Health benefits of IF:

Now that we know what it is about, let's have a look at the health benefits of IF:


Weight loss:

IF has definitely proved its effectiveness in weight loss. A huge amount of scientific work has been done with IF. And there is enough science that proves that IF helps with weight loss.


The first reason why this works is, that you simply decrease your calorie intake when practising IF. It’s almost as simple as that. If you eat fewer calories that you burn you lose weight and vice versa.


But there seem to be other benefits regarding weight loss when doing those intermittent fasts.


  1. Hormones: IF (IF) can affect the production of different hormones that are involved in weight loss (more exactly in hunger, fat storing and metabolism):
    1. Insulin: As soon as we eat something, (all above food that contains carbohydrates), our pancreas secretes insulin. Insulin is the key for the glucose molecules to leave the bloodstream and enter the cells of the tissue where it is used immediately or stored for later energy use. This can be muscle mass, the liver or, if they are both are full and there are still carbohydrates left to be stored, the  fat tissue. If we don't eat and no insulin is produced or released, the body uses fat or other metabolites for energy production.
    2. Human growth factor (HGF): Human growth hormone is responsible for maintaining the muscle mass during fasting periods. It’s production is stimulated by fasting. The main problem of general calorie restrictive diets is, that people lose muscle mass instead of excessive body fat. This is not the case with IF.
    3. Leptin & ghrelin: Those two hormones are responsible for hunger & satiation. Leptin is the hormone produced by fat cells which turns off appetite and makes us stop eating. Ghrelin does just the opposite, it increases the appetite. Fasting reduces ghrelin levels.  
    4. Noradrenaline: When going on a calorie restricted diet, many times the outcome is that our metabolism shuts down, so we don't lose weight even if we eat less. Not so with IF. Fasting periods stimulate the production of noradrenaline, which increases the metabolism.

The above mentioned hormones are not only involved in weight loss related metabolic functions, they play important roles in other aspects related to our health, which leads us to the remaining benefits of IF:


Lowers the risk of diabetes type II: A study shows that IF reduces the risk of type II diabetes by decreasing blood sugar levels effectively.


Improves heart health:

There are several factors that increase the risk of cardiovascular conditions. Those are:

  • High blood pressure
  • High cholesterol
  • High Triglycerides

One study has reported that IF leads to a reduction of all three risk factors.


Reduces inflammation:

Chronic inflammation is involved in many of today’s chronic conditions. These include: Crohn’s disease, arthritis, atherosclerosis, asthma, cancer and Alzheimer’s disease.

A recent study has found a positive impact of fasting on chronic inflammation. IF leads to the productions of a compound that blocks a part of the immune system that is involved in the above mentioned inflammatory diseases.


Promotes longevity:

The last but perhaps for many people most important point is that calorie restriction in general has been linked to longevity for quite some time already.


A recent publication has now shown that fasting is able to reprogram mitochondria, the energy producing structures in cells. They are highly involved in lifespan, the ageing process and connected to that the probability of developing age related diseases. This is a crucial step towards the understanding of the ageing process and how to slow it down or to make it a healthier and thus more enjoyable process.


There are really big benefits of IF, not only for weight loss. We are used to eat or aback all of the time. Our bodies have almost forgotten how it feels to be really hungry.


IF can be a way of getting to know your body in terms of hunger, food intake and satiation. Try it out and see how it benefits you.