Reducing carbohydrate not only lowers your calorie intake, but it also lowers your insulin levels, which puts your body in fat-burning mode rather than fat-storage mode. The job of insulin is to transport glucose and fatty acids from the blood into cells. When insulin levels are high (e.g. after eating a high-carbohydrate meal), the body stops burning fat and burns carbohydrate instead. It also makes the body store excess carbohydrate (as glycogen or fat) and fat. By reducing your carbohydrate intake, you will lower blood glucose levels and insulin production, which means less fat storage and more fat burning. In other words, the body will turn to fat (not carbohydrate) for fuel.