The body uses most carbohydrates quickly, and can only store about one day's worth as glycogen in the liver and in muscle tissue. If you eat normal amounts, Dr. Fats on the other hand, are not metabolised right away. They are stored as fat in adipose tissue, which has an almost unlimited capacity to bulge with fat. Unlike carbohydrates, fat calories don't cause feelings of fullness, so you keep eating and eating, gaining weight, and increasing your risk of all the fat-related diseases.
Carbohydrates including fruits, vegetables, beans, and grains provide most of the body's energy.
They are a main source for body energy. If weight controlled is concerned, limit your fat calories and you don't have to worry about total calorie intake. The same goes for sugar. Cakes, chocolates, icecream are fattening not because it contains sugar, but because it is loaded with fat. Milk is only linked to mucous production in the case of true food allergy.