However, there\u2019s also a lot of evidence to say that it is an effective form of dieting. Another recent meta-analysis in 2025 looked at only one type of fasting \u2014 the 5:2. This big study was made up of over 20 randomised control trials with almost 1,400 people. It found that the 5:2 diet significantly reduces body weight, body mass index, waist circumference and body fat percentage. It also significantly reduced a range of cardiovascular markers, including LDL cholesterol (the bad cholesterol) and blood pressure. <\/p>\n
The study found that it was safe and tolerable, with only mild symptoms reported. This was when compared with control groups, who were often advised to continually restrict their calories. <\/p>\n
Initially, my dad used it to reverse his own type-2 diabetes<\/a>, lose weight, and keep it off. When he was at university he was pretty slim but, like many people, he gradually put on a little bit of weight every year \u2014 half a kilo, a kilo \u2014 to the point where by the time he reached his fifties, he was overweight and had developed type-2 diabetes. <\/p>\n Dr Michael Mosley<\/p>\n NICK HOLT\/CHANNEL 4<\/p>\n At that time, back in 2012, it was only just being considered that diabetes was reversible by losing weight through a dietary approach. My dad made a BBC programme with Horizon, Eat, Fast, and Live Longer, where he followed this new way of eating called intermittent fasting. And essentially, he adapted this into the 5:2 diet, where he\u2019d eat normally for five days a week and really restrict his energy intake to 500 or 600 calories for two non-consecutive days a week. <\/p>\n The concept of intermittent fasting<\/a> is based on the fact that the body is in a state of either growth or repair mode. And in our modern life, we\u2019re constantly in growth mode, because we\u2019re constantly fuelling our bodies with calories. When you are fasting, you then switch into repair and clean-up mode, known as autophagy. <\/p>\n The other key concept behind fasting and the 5:2 is that on those fasting days you burn off the glycogen stored in your liver and also in muscles \u2014 that is, you burn off that carbohydrate and sugar \u2014 and go into ketosis and fat-burning mode. <\/p>\n Consequently, my father was able to lose more than 9kg in weight and reverse his type-2 diabetes. He remained in good health thereafter and kept the weight off long-term by occasionally dipping back into doing a fast day here and there. What also helped was that he improved the quality of his nutrition by following a Mediterranean-style diet. <\/p>\n \u2022 How to cheat the Mediterranean diet (when you\u2019re back home)<\/a><\/p>\n He really did spark this global phenomenon where lots of people started doing the 5:2 diet around the world, from politicians, to celebrities \u2014 the US chat show host Jimmy Kimmel said he was doing the 5:2 after watching the programme \u2014 and normal people. I regularly meet people who\u2019ve seen massive benefits from following the 5:2 and have lost lots of weight. <\/p>\n Does fasting also affect longevity? While more research is needed in humans, animal studies show that calorie restriction can extend lifespan. The reasons for this have been linked to autophagy, reduced inflammation and improved mitochondria (the power stations of the cell). And fasting is said to mimic some of these calorie restriction benefits, and can improve cardiometabolic markers in humans, such as insulin sensitivity, inflammation and cholesterol.<\/p>\n But importantly, some people find this approach much easier and more doable than continuous energy restriction, as they\u2019re not having to think about what they\u2019re eating day in day out. Because that does take a toll. <\/p>\n We only have so much willpower, so it can become harder to do over the long term. We used to think that slow and steady wins the race, but one of the reasons that many people give up on a traditional diet is that when you\u2019re eating only slightly less each day, it\u2019s less motivating because you\u2019re not seeing such rapid results.<\/p>\n My book, Food Noise, is about the GLP-1 weight loss medications, the best approach to follow while you\u2019re taking them \u2014 and after you come off them. Your \u201cfood noise\u2019\u2019 can come rushing back and so it\u2019s important to consider what you\u2019ll do when that happens \u2014 and following the 5:2 is one of my suggestions. <\/p>\n \u2022 Read more expert advice on healthy living, fitness and wellbeing<\/a><\/p>\n This has been echoed by Susan Jebb, the professor of diet and population health at the University of Oxford. She released an academic review about the rapid weight regain after coming off GLP-1s compared to after traditional dieting and mentioned the 5:2 as an option for weight-loss maintenance.<\/p>\n The 5:2 gives people a bit more agency and control than traditional dieting methods. People also tell me that it\u2019s given them more understanding about what to eat \u2014 what foods are filling for them, and which are empty calories. <\/p>\n Many have reversed their diabetes and dramatically changed their lives. So many people have managed to come off blood-pressure medication, reduce their cholesterol<\/a> and even reverse their diabetes. It has been fantastic for a lot of people. It has helped hundreds of thousands across the globe.![\"Dr.](\"https:\/\/www.newsbeep.com\/ie\/wp-content\/uploads\/2026\/02\/\/95b39d7b-c6fb-4b4f-9c08-2ed515c5d9da.jpg\")
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As told to Anna Maxted<\/p>\n