Fat is necessary for human health and together with carbohydrates and proteins, gives us the energy to live. Fat also helps us by allowing the `fat soluble' vitamins A, D, E and K to be transported around the body and utilised where needed. However, having too much fat is responsible for many health concerns, and in most cultures (though not all) is considered to be unattractive, so at any one time millions of people around the world are dieting to reduce the fat content of their bodies.