This mantra is too simple and rather patronizing and tends to be the advice of the lucky slim commentators, who as a consequence of their interest in health are likely to have a 'healthier' diet already. It is what they eat, not their willpower and Sunday morning jogs that is keeping them slim.
Assem Malhotra's advice: “You can’t out-run a bad diet!“ has become a favorite slogan of mine. Yes exercise is very good, but diet is a much bigger factor in weight management.
Over the past 7.5 months of LCHF diet my weight has consistently been about 11 stone 6 lbs. My average training has been low (due to injuries) about 4 hours per week. We just had a 2-week holiday in France during which I reverted to a carb-based diet, I did not noticeably eat more than normal although I was not counting calories – I never do. I trained for about 8 hours per week and my weight rose to over 12 stone.
Imagine what would happen if we led half a class of children to a table covered in sugary drinks, sausage rolls, sandwiches and and donuts (typical kids party food) and the other half to a table covered in water, chicken salad, strawberries and cream (a typical adult summer lunch in Hassocks). We then invite the children to eat as much as they like. Lots more food (and lots more calories) would be eaten by the first half, even though many children and adults would admit that the second table tasted just as good or better.