Fat-rich foods. Selection of fat-rich foods presented in test tubes to depict the modern scientific techniques of food processing. Fat supplies the body with its most concentrated source of energy. Some dietary fats are sources of the fat-soluble vitamins A, D, E and K. However too much fat in the diet can lead to obesity and heart disease. The foods shown here are all rich natural sources of fat. They are (from left) pork, cheese, beef, egg and fatty fish. The modern diet, however, relies much less on these natural sources of fat. Instead fat is scientifically manufactured as an ingredient for processed foods.