What is the Glycemic Index and how can you use it to your advantage?
The GI or glycemic index is a measure of how quickly carbohydrate in food affects blood sugar levels. A low GI food releases glucose more slowly and steadily whereas a high GI food results in a faster increase in blood glucose levels. For example, coarse grained, heavy bread will have a lower GI than white bread due to the fiber.
Factors that influence GI of a food include:
- Type of fiber in the food (soluble fiber has low GI)
- Form in which the food is eaten (rice cakes have a higher GI than cooked rice)
- Presence of fat
- Form of sugar in the food (fructose causes less of an increase than glucose or sucrose)
- Effect of protein and fat eaten with the carbohydrate food
- Starch structure in the food (amylase has lower GI than amylopectin)
Here is a general list of foods and their approximate GI values
High GI (>85)
Glucose, Sucrose, Maple syrup, Corn syrup, Honey, Corn flakes, Crackers, Molasses, Potato, Raisins, White bread, Soft drink, Sport drink.
Medium GI (60-85)
All bran cereal, Bananas, Grapes, Oatmeal, Orange juice, Pasta, Rice, Whole grain rye bread, Yams, kumara, Corn, Baked beans, Potato chips and peas
Low GI (<60)
Fructose, Apple, Applesauce, Cherries, Kidney beans, Navy beans, Chick peas, (Garbanzo beans), Lentils, Dates, Figs, Peaches, Plums, Ice cream. Milk, Yogurt, Tomato soup and Peanuts
When High GI can be beneficial?
Within 1hr of training or competition, immediately after a strenuous training session to help promote glycogen store replenishment or during a training session >60-90min to ensure adequate energy to perform. Although the GI can be useful, it should not be used solely in making food choices; for example ice cream has a low GI, but it does not make it a healthy food choice to enjoy every day. **To help meet weight loss goals, lower GI foods and portion sizes should be considered.