It is true that slow cardio exercise burns more fat than carbohydrate when compared to the fat-burning properties of more intense high-impact exercise. But the trade-off is that slow cardio exercise burns fewer overall calories per unit of time spent exercising. High-intensity exercise burns proportionally more carbohydrate than fat, but you also burn more calories overall. This translates to larger calorie deficits, which are later paid back with a reduction in stored body fat.
Being quizzed by chemist's assistant in Boots.