Almost one third of British children are now overweight or obese before they reach secondary school. The obesity epidemic across Britain looks set to continue unless we act now. But are we able to stop fat children becoming fat adults? And what about the two thirds of adults who are overweight or obese? We follow 39 year-old Joy who, with a BMI of 50, is desperate to lose weight and has opted for a gastric bypass. In contrast, the Purvis family are hoping to shed their extra pounds by changing their lifestyle and incorporating healthy eating and exercise.