Dr Michael Mosley issues warning for everyone doing exercise to lose weight

Health and diet expert Dr Michael Mosley has revealed how long you'd have to run to burn a single pound of fat

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Health and nutrition expert Dr Michael Mosley has explained how far you'd have to run to burn one single pound of fat.

Dr Mosley, the TV producer and presenter who is the creator of the 5:2 and Fast 800 diets, was exploring the theory that exercise will make you lose weight. Journalist Lydia Stephens tried the Fast 800 diet for a week and couldn't believe the results.

In an article on the Fast 800 website, Dr Mosley said it was a "diet myth" that exercise helps you lose weight, saying "that isn't what actually happens". He said: "It seems incredibly obvious. Do some exercise, burn some calories, lose weight. But that isn't what actually happens. Part of the problem is that fat is very energy dense. You would need to run for about 36 miles to burn off a single lb of fat."

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It is not the first time the simple theory that exercise leads to weight loss has been challenged (though, of course, exercise has a number of important health benefits). In a 2016 study reported by The Guardian, researchers said their work suggested exercise alone is not enough to lose weight because our bodies reach a plateau where working out more does not necessarily burn extra calories. One of the report's authors, Prof Herman Pontzer of City University of New York, said: "Exercise is really important for your health. That's the first thing I mention to anyone asking about the implications of this work for exercise. There is tons of evidence that exercise is important for keeping our bodies and minds healthy, and this work does nothing to change that message. What our work adds is that we also need to focus on diet, particularly when it comes to managing our weight and preventing or reversing unhealthy weight gain."

In his recent article, Dr Mosley adds: "The other problem is that people often reward themselves for doing exercise by having a treat. If you run for a mile you will burn about 120 calories; but if you then decide to eat a small bar of chocolate, you will consume 240 calories. There are lots of benefits to be had from doing exercise, but losing weight is unlikely to be one of them. That said, exercise is a great way of stopping you putting weight back on once you’ve lost it."