Fat: what good is it? Like most things in this world, fat has its uses. If you're an Eskimo, for example, a good layer of fat is essential for insulation against life-threatening cold and provides a rich source of calories to replace those used up keeping warm. Fat also cushions internal organs and helps absorb shock.

Our bodies evolved during times when food was scarce, and fat was stored in good times to keep us alive in case of bad harvest. Now there's plenty of food (in the West, at least) and it's richer in fat - but our bodies haven't got the message. The brain, it seems, still assumes that the next Double Cheeseburger Combo could be the last before the great famine. There's no cut-off mechanism when it comes to fat.

Why do we crave fatty foods in particular? Fat is a highly concentrated source of calories. Each gram of fat contains nine calories - more than twice as much as that found in carbohydrates or protein - and because calories equal energy, it's a ready source of get-up-and-go. Fats also contain less oxygen than other nutrients, so they oxidise more rapidly and release more energy.

Perhaps the major reason we crave fat, though, is that it tastes good. Fat is an excellent flavor carrier; it has what food chemists call a "superior mouth feel". Without it, cakes wouldn't be moist and ice cream wouldn't be smooth. Some things, like soft drinks, increase our fat cravings. Soft drinks, packed with "empty" calories (once you've burned up the sugar, there are no nutrient left), sweeten the palate and prepare the body to digest calories: knock back a Coke, for example, and your body is primed for a high-fat, high-sugar meal (a Big Mac and Coke perhaps, or a Double Whopper with those free refills?).

Yes, fat, whether you live on the freesing Steppes of Russia or beside a tropical beach, appears to be the top taste treat. We all know about potato chips and pork scratchings, but they're pretty mild on the calories barometer compared to some countries' favorites. How about a glass of melted pig lard - a favored tipple before setting out on a hard night's drinking in the Czech Republic? Or you might prefer this Moroccan treat called khil: fatty lamb, seasoned with spices, simmered in olive oil and melted lamb fat for eight hours, left to dry in the sun then served on hot bread, with egg or tomato topping? If you're a Greenlander, of course, you'd probably die for a plate of diced whale blubber, served raw, with a side serving of dried whale meat and boilde potatoes (a mere 1110 calories).

A certain amount of fat is essential for our wellbeing. It's recommended that 30-33 per cent of our total calorie intake should come from fat. This equates to about 40-60 grams fo fat a day. Choose food containing under 10g of fat per 100g and you're on the right track.

It pays, then, to know which foods contain the most fat. Sometimes it's pretty obvious - but sometimes it hides in the most unlikely places.

Carry on for a quick run-down on some of fat's favorite hang-outs.