Dr Jason Fung, a practising kidney specialist from Toronto, Canada, has revealed that the physiology of obesity is more complex than simply counting calories. He argues that obesity is a hormonal imbalance, not a calorific one, as high insulin levels drive you to store fat. Despite numerous studies showing that calorie consumption decreases, exercise does not increase calorie burn, as the body compensates by slowing metabolism afterwards. Fung's new book, The Hunger Code, outlines the science-based secrets of long-term weight loss and health. He states that for every calorie eaten, the body could either store it or burn it, and if it burns it, it will not gain fat. The most important factor determining our body weight is hormones, which tell us to feel full and store body fat.