I am the most unlikely author of a bestselling diet book. This wasn’t something I have ever imagined doing and at 55 I am hardly a glamorous role model. Sometimes you just stumble on things.
It all started about nine months ago when the BBC science series, Horizon, asked me to take part in a film looking into the science of life extension and dietary manipulation. We soon focused on Intermittent Fasting, or IF. Unlike proper, hard core fasting where you might go for days on end living on zero or near zero calories, IF involves days in which you eat a quarter of your normal calories.
Although I was sceptical, I decided it would be worth testing and also a chance to finally do something about my own little problem: I am, or rather was, a TOFI – in other words Thin on the Outside, Fat Inside.
If you look at photos of me from that time I don’t look fat, but that’s because it’s hidden, visceral fat. It doesn’t sit beneath the skin, it lurks inside the body. An MRI scan revealed that I had many litres of fat inside my abdomen, coating my internal organs. It’s a particularly unhealthy type of fat distribution because it significantly increases your risk of diabetes and heart disease.
The medical back in May 2012 revealed I was around 187 lbs, which made me slightly overweight. My waist, at 36in, was more than half my height, 5ft 11, which is one of the clear warning signs. Worse still I was borderline diabetic and my LDL (low density lipoprotein, ‘bad’ cholesterol) was also far too high.
So I went off and made the film, in the course of which I discovered a great number of surprises about intermittent fasting and about myself. I discovered that human trials of intermittent fasting suggest that it is at least as effective, and perhaps more effective as a way of losing weight than standard low calorie diets. There is also compelling evidence, mainly based on animal studies but increasingly based on human studies, that those who stick to it will reduce their risk of cancer, diabetes and dementia.
There are different ways you can fast; after some trial and error I settled on a pattern called 5:2; five days you eat normally, two days you eat a quarter of your normal calorie needs. For men that means 600 calories a day, for women 500. On the 5:2 diet I lost 19lbs, mainly fat, my waist measurement went down to 32 inches and my biomarkers, like fasting glucose and LDL, improved markedly.
At this point my wife, who is a GP, said she thought I should slow down, so I switched to mainly a 6:1 pattern. I feel extremely healthy, but at some point I will probably go back to two days and week and lose a bit more weight.
So why has the diet taken off? Mainly, I think, because most people who have tried it have seen good results and in a digital age they can readily communicate. I think it also helps that I have a scientific background and try not to make overblown claims.
This is by no means the last word; a number of human trials are currently underway and others are just starting. Hopefully they, and subsequent trials, will identify whether people who lose weight through an IF diet are able to keep it off, the true long term health benefits of IF and what is the best pattern of fasting intermittently.
I feel hugely fortunate to have benefited from this research and become involved in something that really does feel like it could make a difference to the lives of millions.
Michael Mosley presents Winter Viruses and How to Beat Them - Monday at 9pm on BBC2
Michael Mosley's series The Genius of Invention continues this week on Thursday at 9pm on BBC2