Exercisers often stay within 60 to 70 percent of their maximum heart rate – also known as the “fat-burning zone” – in order to burn a higher percentage of calories from fat. Problem is, your calorie-burn total will be lower than if you were to up your intensity – and when it comes to fat loss, the quantity of calories burned is more important than the type.

Case in point: when Australian scientists manipulated the genes of mice to only burn fat (the goal of staying within the fat-burning zone), unused carbohydrates were stored as fat – basically reversing their efforts altogether.