GI Index
Foods with a high glycemic index (GI) contain carbohydrates that will dramatically raise your blood-glucose levels, while a low GI food will raise it much less.
The substance that produces one of the greatest effects on blood-glucose is glucose itself. Thus the glycemic index of pure glucose is set at 100, and every other food is ranked on a scale from 0 to 100 according to the actual effect on blood-glucose levels.
Testing:
- An amount of food containing an equivalent amount of carbohydrates (25 or 50 mg) is given to a volunteer.
- Over the next 2 hours blood is taken every 15 min to measure the blood glucose of these samples.
- The volunteer’s response to the food (spaghetti is used below) is compared with his or her own response to 50 mg of pure glucose.
- The average GI value found in 8-10 people is the GI value of the food.
Figure. Measuring the glycemic index value of a food
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Hence GI of spaghetti is 41 |
Source: Brand-Miller, J et al. The New Glucose Revolution
Here are some of the GI indices of some foods. To find out more about GI Index I recommend The New Glucose Revolution by Jennie Brand-Miller et al.
G.I. RANGES: The figures form a continuum but in general:
LOW G.I. FOODS below 55
INTERMEDIATE G.I. FOODS between 55 and 70
HIGH G.I. FOODS more than 70