Eating pure glucose is given a ranking of 100 -- all other foods are in relation to this. So a food with a glycemic index of 95 raises blood sugar almost as much as pure glucose, but a food with a glycemic index of 20 doesn't raise blood sugar much at all. It's important to keep in mind, though, that the glycemic index does not take portion size into account. The actual amount any food raises blood sugar has to do both with how glycemic it is, and how much of it you eat.
These numbers can be a tad misleading as well - for example, the glycemic index for lowfat milk and a small portion of peanut M&Ms is the same. Obviously, the milk is the better ( and Clean ) nutritional choice.
o Low GI foods are foods with a GI less than 55. They cause a slower and
lower rise in blood glucose levels. Examples are Porridge, Apple and Sweet Potato.
o Intermediate GI foods are foods with a GI between 55 and 70. They cause
blood glucose levels to go up at a moderate rate. Examples are Pineapple, New Potato and Mango.
o High GI foods are foods with a GI greater than 70. They cause a rapid rise in
blood glucose levels. Examples are Jasmine rice, Cornflake and Watermelon.
GI of some basic carbohydeate heavy foods
Low Glycemic Load (55 or under)
- High-fiber fruits and vegetables (not including potatoes)
- Bran cereals (1 oz)
- Many beans and legumes, including chick peas, kidney beans, black beans, lentils, pinto beans (5 oz cooked, approx. 3/4 cup)
Medium Glycemic Load (55-70)
- Pearled barley: 1 cup cooked
- Brown rice: 3/4 cup cooked
- Oatmeal: 1 cup cooked
- Bulgur: 3/4 cup cooked
- Rice cakes: 3 cakes
- Whole grain breads: 1 slice
- Whole-grain pasta: 1 1/4 cup cooked
- No-sugar added fruit juices: 8 oz
High Glycemic Load (70+)
- Baked potato
- French fries
- Refined breakfast cereal: 1 oz
- Sugar-sweetened beverages: 12 oz
- Jelly beans: 10 large or 30 small
- Candy bars: 1 2-oz bar or 3 mini bars
- Couscous: 1 cup cooked
- Cranberry juice cocktail: 8 oz
- White basmati rice: 1 cup cooked
- White-flour pasta: 1 1/4 cup cook
I would encourage you to do a little research on the Glycemic Index of various foods, and keep it in mind when building meals and snacks. Ideally, you'll want the balance of your meals to be in the low and medium GI areas, with occasional forays into high GI that are again balanced out by a low GI food.
Check out this PDF for an 8 page list of common foods and their GI index. http://www.glycemicindex.ca/glycemicindexfoods.pdf