Many people try to lose weight by going on low-fat diets, but actually gain weight.
Two recent papers show that a low-fat diet helps you to lose weight and lower cholesterol, only when it forces you to eat fewer calories. Both groups lost the same amount of weight and lowered their cholesterols equally. A low-fat diet should help you lose weight because fat is the densest source of calories. It has more than twice as many calories per gram as protein and carbohydrate, but a lot of people replace fatty foods with carbohydrate-rich foods that are low in fiber. Fiber fills you up without contributing extra calories.