What differentiates the 5:2 diet from other diets is that although it incorporates calorie counting on fast days, it still gives you room (5 days a week) to not have to worry about you eat. Hurrah!
People who follow the diet also report that it is one of the easiest ones to stick to as 'you're never more than a day away from eating what you like'.
Dieters also say that they have more energy on the fast days and don't feel the urge to over-indulge on non-fast days to compensate, according to Rachel Hosie.
So what exactly is the 5:2 diet? HuffPost UK Lifestyle editor Poorna Bell enlisted a range of experts to explain.
The 5:2 is a diet incorporating intermittent fasting. You 'fast' for two days eating only 500 calories per day and for the other five days, you can eat whatever you want.
Can this diet help with diabetes?Dietitian Priya Tew says: "There is some limited evidence suggesting that the 5:2 diet can have beneficial effects on certain cancers and chronic diseases such as type 2 diabetes. Further research is needed to look at the long term effects of this diet on weight.
"Essentially this diet limits the calorie intake on 2 days so reducing the calories eaten in the week. The issues can come on the fasting days, when the fasting can impair concentration and mood plus making it difficult and not sensible to exercise, so this diet could be impractical."
Francesca Fox, diet and fitness expert from Francesca's Fit Kitchen says: "I am not a fan of anything to do with fasting because I feel it can be a short sighted approach to lifestyle and can lead to binge/purge cycle for anyone prone to disordered eating."
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HuffPost UK blogger and dietitian Chloe Phillips says that "Although anecdotally I have seen some great success with this diet, in particular those types of people who have always struggled with the 'restriction mindset' and 'being on a diet' 24/7, there is still limited evidence supporting the ideal intermittent fasting pattern, ideal calorie consumption and the sustainability of the diet, therefore always should be carried out under medical and dietetic supervision."
Fitness author Sam Feltham is a fan of intermittent fasting but has some fundamental issues with 5:2.
"I openly encourage people to try it under the guidance of a structured program as long as they have no previous history of eating disorders. However, my problem with the 5:2 diet is that firstly it still goes by the hypothesis that to lose weight we need to simply expend more energy than we consume and secondly that you can just eat "normally" which usually means sugary cereal for breakfast, sandwiches for lunch and pasta for dinner a triple threat of Alzheimer's, diabetes and heart disease if I ever saw one.
"You can still develop these diseases void of how slim you are, 40% of people with metabolic syndrome have a normal BMI."
Hungry for more? Here are some fab 5:2 diet recipes