In nutrition, the diet is the sum of the food consumed by a body. Proper nutrition for a human requires vitamins, minerals, proteins, and fuel in the form of carbohydrates and fats. Imbalances between the consumed fuels and expended energy results in either starvation or excessive reserves of adipose tissue, or body fat.
Changing the dietary intake or going on a diet can change the energy balance and increase or decrease the body fat of a body. Some foods are specifically recommended, or even altered, for conformity to the requirements of a diet, and are frequently labeled "diet foods".