A look at the science of calories, examining new findings about so-called fat and skinny genes that appear to affect appetites, making over - or under - eating more likely. Along the way the programme busts some myths about calorie burning. For one sitting only, maître d' Fred Sirieix welcomes 20 unsuspecting diners to lunch at a restaurant like no other - because behind the scenes there is a secret. Dr Zoe Williams has a group of fitness fanatics poised on bikes, treadmills and rowing machines, where they will exercise away every single calorie ordered by the unwary diners