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5:2 diet: what is it and does it work?

We ask a nutritionist all about the diet that's showing no signs of slowing...

Alice Howarth

The 5:2 diet has been around for many years but instead of disappearing like many other 'it'-diets which have in the past - it doesn't seem to be going anywhere. We tracked down Nutritionist Resource member Sonal Shah to find out exactly how it works, what you can eat and what the benefits and risks of it are... 

What is the 5:2 diet?

Originally slated as a more modern approach to the Dukan or Atkins diet, the 5:2 diet went viral in 2012 after Michael Mosley's documentary, Eat, Fast And Live Longer, highlighted the potentially huge benefits of it.

It works like this: two non-consecutive days a week you only eat 500 calories (600 for men) which can be made up of any types of food as long as you keep to within those intake figures. The rest of the week you eat whatever you like - eating the normal recommended amount of calories, 2000 for women and 2500 for men.

Sounds doable, right?

MORE: Tom Kerridge’s 12 stone weight loss: How he started his epic transformation from fat to thin

What food can you eat?

Any - no food group is off limits, the key is just sticking to the calorie plan.

Downloading an app like MyFitnessPal is a great way to clock your calories and find out how many calories are actually in each food. For example a banana typically equates to around 105 calories.

What are the benefits of the 5:2 diet?

Part of the appeal of this diet is its seaming simplicity. 

"Reducing calorie intake significantly on just one or two days a week, rather than by a little every day, might seem more manageable to many people," says Sonal. Essentially, the more straightforward a plan is, the more likely people are to stick to it which could result in successful weight management. 

READ MORE: See what 'foodie' Meghan Markle eats in a day

What are the risks of the 5:2 diet?

Ultimately, it can be difficult to stay energised and focussed on the days that you are fasting as you will only be consuming 25% of the amount of calories you normally do which can leave you feeling weak. On top of this, it's also not uncommon to experience difficulty sleeping, fluctuating moods, bad breath and constipation. 

"On the non-fasting days there is no calorie restriction so it is also possible for someone to over exceed calorie consumption too," warns Sonal. 

"Exercise may also be difficult to perform on the two fasting days. Benefits of physical activity on weight loss are so important and I would prefer someone continues to exercise daily than to restrict their calorie intake considerably which could also slow down the metabolism."  

"Essentially", says Sonal, "there is ultimately limited research on intermittent fasting at the moment as many are based on short-term studies so we do not know if the weight loss is sustained long term." 

READ NEXT: What is the Keto diet? Find out more

If you are attempting to follow a weightloss plan of any kind, you must consult your GP or medical professional beforehand. Calorie restriction can result in long-term risk to your health. 

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