Does the 5:2 diet really work?

As fasting diets grow ever-more popularity, we take a closer look Discuss this article

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With intermittent fasting and the much talked about 5:2 diet growing in popularity, nutritionist Gaby Taylor explores the ins and outs of this controversial approach.

With fasting diets growing in popularity every week, and as I hear more and more people talk about the controversial 5:2 diet – where you eat normally for five days a week, but fast for two – I decided it was time to delve a bit deeper and look at the ins and outs of what sounds like the solution to all our dieting dilemmas.

Could one of the latest fad diets actually be a long-term way of maintaining a healthy body and weight? I’m sceptical…

First popularised in the UK in 2012 by Dr Michael Mosley, the 5:2 diet is based on five days of normal eating and two days of fasting each week – though not consecutively – eating around one quarter of your recommended normal calorific intake, so 500 for women and 600 men.

It works by sending your body into ‘repair mode’ rather than storing fat (starvation mode), which can happen when you just cut down on calories altogether. This ‘repair mode’ causes the body to restore damaged cells, which uses more energy. It also claims to help shift your body from burning sugar and carbs to burning fat as its primary fuel.

To be clear – this is not about binging on fast food followed by a period of starvation; you will need to eat healthily on your non-fast days for the diet to have a chance.

Supporters of this new diet claim it is great for weight loss – women can lose up to half a kilogram a week, and men even more. It can help you live longer, look younger and can protect the brain against illnesses including Alzheimer’s and Parkinson’s.

Additionally it helps to reduce cravings for sugar, increases your metabolism and seems very easy to integrate into a busy lifestyle. You can move your fast days around to suit your diary, and you can still enjoy meals out and socialising on non-fast days. The majority of people who try it say you don’t get the boredom of restricting calories on a daily basis.

Individuals also report that once they are into the swing of things, they are generally more aware of what they are eating on non-fast days and claim to eat healthier on these days than before they started the diet.
But as a disclaimer – this diet is still at the experimental stage with very limited evidence and research on the safety and effectiveness of it. So if you plan to attempt the diet, it is recommended to consult your GP.

I have spoken to friends of friends who have actually put on weight doing the 5:2 diet. As the diet dictates that you can eat anything you like on non-fast days, people often binge on fatty, sugary foods even more than they did before they dieted. To ensure this doesn’t happen to you, I would suggest you do two weeks initially of just eating healthily, so that you become more aware of the foods you are eating and their calories. You will then be in a better position to fast and stay healthy in between.

The 5:2 diet suggests breaking your fasting days into two meals – so a breakfast and lunch or breakfast and dinner – depending on what suits you and when you exercise. You will need to be aware of portion control and counting calories too, as your meals will be considerably smaller so watch your labels. Download a smartphone app such as Meal Snap ( to check the calorie content on the meat, fish, fruit and veg you eat.

Initially, fast days are said to be hard. Expect hunger pangs, loss of energy and teenage mood-swings.

The verdict
I am still a little sceptical. Although the science behind it does makes sense and the results sound amazing. But can it really work for those who aren’t already eating healthily? Moreover, a healthy diet is not just about calories – it is about eating foods rich in vitamins, minerals, essential fat, fibre and the like, and on fasting days it is very unlikely that the body will get its recommended nutrient intake.

Also, what happens when you stop? Does the weight pile back on? Can you actually maintain this long term?

I guess the only real way to find out if it works is to fast myself. And I’ve decided May is the month.

Keep your distance everyone!

By Gaby Taylor
Time Out Doha,

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