'Fat' has become a byword for ill-health in our nutrition obsessed world. Yet fats, or more exactly fatty acids and their glycerol esters the mono- di- and triacylglycerols are essential to health. They are so important that humans have evolved mechanisms which ensure that we greatly desire fats in all their delicious forms, in baked goods, chocolate, confectionery, ice-cream, dairy products, the list just goes on and on. Their importance is testified to by the fact that fat and vegetable oil refining and production, together with goods such as fatty spreads and chocolate are the single most important food sector in the world.