Seven years ago I discovered, thanks to a chance blood test, that I was a type 2 diabetic. Rather than start on medication, I wanted to see if there was another way to reverse my diabetes. So I made a Horizon documentary called Eat, Fast, And Live Longer during which I discovered the joys of intermittent fasting. The idea behind this approach is that you can lose weight  and improve your health by significantly cutting your calories a few days a week, or by going for longer periods than you normally would without eating.

A popular form of intermittent fasting is the 5:2 approach. This involves cutting your intake to around 600 calories a day for two days a week, then eating healthily for the other five. Using 5:2, I lost nine kilograms and returned my blood sugar levels to normal. Others have done likewise. A recent controlled trial of type 2 diabetics doing the 5:2, published in the journal JAMA, found average weight loss of around seven kilograms, sustained for over a year. 

But there’s another form of intermittent fasting, called Time-Restricted Eating (TRE), which has recently taken off. The rules of TRE are simple: you try to eat most of your calories within a small time window, such as eight hours. Once you have decided your time window (perhaps 11am to 7pm) you don’t eat or drink anything that contains calories outside of that time window. The person who pioneered TRE is Dr Satchin Panda at the Salk Institute in San Diego, one of the world’s  leading research centres for biomedicine and life sciences. In 2012 he and his colleagues published a study in the journal Cell Metabolism, where they took two groups of mice and fed them a high-fat, high-sugar diet. All the mice got exactly the same amount of food, the only difference being that the mice in group A were allowed to eat whenever they wanted, while the mice in group B had to eat their food within an eight-hour time window. This meant that there were 16 hours of the day in which they were fasting.

YOU TRY TO EAT YOUR CALORIES WITHIN A SMALL TIME WINDOW

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