The Fast Diet: Lose Weight, Stay Healthy, and Live Longer with the Simple Secret of Intermittent Fasting

"Yes. So in 2012, Michael was doing a documentary series about diets, and came across a group of people advocating what was called ‘intermittent fasting’. This means that either every other day, or for two days a week, you will either fast completely or consume only 25% of your normal calories. The rest of the time you just eat normally. The idea was that you reset your metabolism and allow your body to rest. You’re able to lose weight on this diet, because you don’t overeat as much as you might think on the other days. This really caught on. Michael didn’t invent the diet, he basically took it from other scientists and made it very popular and accessible. I think he’s sold a million copies of that book. And it’s probably the only diet I would recommend, because it doesn’t stop you eating what is good for you, it just alters the way you eat. It’s not what you eat; it’s how you eat. You might eat exactly the same total amount in a week and just rearrange the way you eat it. I think this was the first time that people actually started to think about the concept of meal timings and other things that might be just as important as the calorie or fat content of the food. People loved the 5:2 diet, and there was a real craze. People are still doing it now, which is a testament to any diet, and the book is still selling. That’s not because it works better than other methods, but because people are more likely to adhere to it after six months. “Intermittent fasting is the only diet I would recommend” People say, okay, I’ll do a ‘hungry day’ tomorrow. I’m working flat out and won’t notice it. All of us do that to some extent. It’s just giving you a good rationale about why you should do it. This way of eating has evolved into another form, called ‘restricted time feeding’. There are a number of books on that. Rather than four or five or six ‘meal events’ in a day, you just have two. Most people will lose weight and have a better metabolism. So it was from the idea of increasing the fasting time. It turns out that the longer you fast overnight or during the day, the longer your body is not dealing with food and the better and healthier your metabolism. A lot of that’s coming from gut microbes. Your gut health is better when they have time to recover, heal, tidy up your gut lining, help your immune system. Or that’s the current theory, and increasing data is supporting that. Our ancestors didn’t eat six times a day and feel faint if they didn’t have a McVitie’s biscuit at 11 o’clock. This is just cultural, learned behaviour. Thirty years ago it was felt that grazing was better than gorging, and that data has been proven to be wrong. But, again, clearly the food industry doesn’t want to change that. Our snack routine in this country accounts for over 20% of our calories, and it’s not just the calories, it’s also the fact we’re not resting our body, our guts. So the new interesting thing is that if we can work out the best time for us to eat, without actually changing the energy content within the food, we can start personalising the way we eat. I think if people start to experiment, they can find what suits them. You mentioned breakfast; studies show that if you randomise people to breakfast or no breakfast, but the same amount of food in a day, people overeat a bit if they miss breakfast, but not so much that they over-compensate. Many parents say that their child is not interested in breakfast. Should they force it down? And my answer is, ‘no’. We’ve evolved plenty of mechanisms to tell us when we’re hungry. We don’t need to be forced. So some people are much better off skipping breakfast. Others are better off eating it. We shouldn’t force everyone to fit into a single size box. With the company ZOE , we’re going to launch a product in the UK next year that will allow people to conduct their own experiments and work out their personalised food profiles using an app. Without changing calories or anything, you just work out which of the foods suits you best. We’re working at about 80% accuracy at the moment, and I think the future is personalised nutrition."