Justin Roberts, Anglia Ruskin University ; Ash Willmott, Anglia Ruskin University , and Dan Gordon, Anglia Ruskin University

When it comes to losing weight, people often want know the best way to shed excess pounds - and there's no shortage of fad diets or fitness crazes claiming to have the "secret" to fat loss. One theory even suggests that exercising at around 60% of your maximum heart rate will bring our bodies into a so-called "fat burning zone", optimal for losing weight.

But does this "fat burning zone" even exist?