The GI of common foods

Potatoes

Potatoes have a high GI. But they are also cheap, plentiful, tasty and contain various nutrients your body needs. You don't have to give up potatoes. Instead, you can:

• Eat them in a meal with other food, especially high-fibre foods, lean protein and small amounts of unsaturated fats. All will lower the GI.
• Eat new potatoes. The more immature the starch, the lower the GI.
• Eat them cooked and cold, as in a potato salad. The starch will have changed into a form that has a lower GI.
• Keep the salt to a minimum.

Chips have a lower GI than baked potatoes because of the fat they've been cooked in. But don't be misled - fat provides excess kilojoules, and if it's saturated fat, which many fast food outlets and supermarket brands still use, those chips will not be good for you.

Bread

White bread has a high GI; most wholegrain is low. But white bread is rather like potatoes - the overall value is influenced by how you serve the food.

If the only sandwiches your kids will eat are made with white bread, give them a piece of high-fibre fruit as well. Kiwifruit, oranges, apples and pears all qualify.

Rice and pasta

They're not the same. The GI of most types of pasta is low, but with rice it varies.

The colour (white or brown) isn't so important, but the length of the grain is: long grain (like Basmati) has a lower GI than short grain.

Pasta differs from rice because it has less "amylopectin", a starch that is quickly digested, and more "amylose", which digests more slowly.

Chocolate and ice cream

And many other kinds of sweets and Christmas treats for that matter, may have a low GI.

But don't be fooled. Chocolate is 30 percent fat and over 50 percent sugar, and some ice creams are little better.

They're not good for your waistline or your teeth!

What's more, treat foods like this have few other nutritional qualities.

If it's time for a treat and you don't fancy an apple, the GI is not a useful guide. Look for a food where the energy content isn't too great.

Watermelon

Watermelon has a high GI rating. But this doesn't mean you should avoid it.

GI is measured using a quantity of the food large enough to contain 50g of carbohydrate. Because there is relatively little carbohydrate in watermelon, subjects need to eat an enormous quantity to do the measurement.

No one would eat this much watermelon normally.