Proof the 5:2 Diet can help fight diabetes, cancer… and even dementia

By Dr. Michael Mosley 

5:2 diet

The 5:2 diet isn’t just an effective way to lose weight. Recent research has shown that the diet can also reduce the risk of diabetes, cancer and even dementia…

A weapon against diabetes

Back in 2012, I was diagnosed with type 2 diabetes and was told that I’d need to start taking medication.

Keen to avoid this, I started to look into what else I could do, and came across something called intermittent fasting – significantly restricting calories for short bursts. The one I found most do-able involved two days of cutting calories, or fasting, a week. I called this the 5:2.

After just 12 weeks on the diet, I lost nearly 20 lb and reversed my diabetes. It worked for me and has for thousands of others.

But I was pleased to see the approach has been backed by an Australian study, published in July, which looked at the effect of the 5:2 diet versus a standard calorie-controlled diet on 137 overweight people with type 2 diabetes.

The University of South Australia trial ran for just over a year, which is long for a weight-loss study. Both groups were given sample menus, met with a dietician regularly for the first few months and ate real food – a very practical test of this approach. After a year, the 5:2 diet group had lost, and kept off, 15 lb on average while the standard diet group had lost 11 lb. Determined people shed most weight.

The 5:2 group also lost 40 per cent more body fat than the standard dieters, and most interestingly, their blood sugar control improved, so many were able to reduce medication.

It could delay dementia 

Neuroscientist Dr Mark Mattson, from the National Institute on Ageing in Baltimore, has spent decades studying intermittent fasting in animals. His experiments have included this diet’s effects on the brain.

In his lab, Dr Mattson showed me mice made more vulnerable to dementia through genetic engineering. When put in mazes and tasked to solve simple problems, these mice were already showing obvious learning and memory problems by one year old – the equivalent of human middle age.

But he discovered that those on an intermittent fasting diet could go nearly two years without any detectable signs of dementia. They only really started deteriorating towards the end of their lives.

In humans, that is the equivalent of developing signs of dementia at 90 rather than 50. I know which I would prefer.

Dr Mattson is carrying out a similar study on people who are showing signs of early mental decline, and I’ll be sharing the results soon.

…And cut cancer risk 

In April 2013, dietician Dr Michelle Harvie, of the Genesis Breast Cancer Prevention Centre at the Wythenshawe Hospital in Manchester, and Professor Tony Howell published study results on what they called ‘intermittent energy restriction’. A total of 115 overweight women with a family history of breast cancer were divided into three groups.

One group stuck to a low-calorie diet rich in healthy fruits, vegetables, fish and nuts, with moderate amounts of meat, dairy and olive oil.

Another group ate a healthy diet five days a week, then a 650-calorie, low-carb version on the other two days.

The final patients were not calorie-restricted except for avoiding carbs for two days a week.

After three months, the women on the two-day diets lost more than 11 lb on average, with some losing as much as 41 lb. Those on the standard diet lost 8 lb on average.

The women restricting calories for two days a week lost almost twice as much body fat, and saw much bigger drops in insulin levels (down 40 per cent), than the slow and steady dieters.

Insulin is important because high levels increase cancer risk, particularly breast cancer, and the likelihood of becoming type 2 diabetic.

So you see, there really is even more reason to give this diet a go. Remember to always consult your healthcare professional before beginning any diet or fitness regime.


The Fast 800 is an innovative approach to healthy living and weight loss based on the latest scientific research.

The Fast 800 online programme has been developed in conjunction with Dr. Michael Mosley for those that need more support and guidance for achieving long lasting health, incorporating the 5:2 diet, intermittent fasting and a lower-carb med style diet.