A low-fat diet is one that restricts fat and often saturated fat and cholesterol as well. Low-fat diets are intended to reduce diseases such as heart disease and obesity. Reducing fat in the diet can make it easier to cut calories. Fat provides nine calories per gram while carbohydrates and protein each provide four calories per gram, so choosing low-fat foods makes it possible to eat a larger volume of food for the same number of calories. The Institute of Medicine recommends limiting fat intake to 35% of total calories to help prevent obesity and to help control saturated fat intake.