How
Glycemic Index is Measured
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GI MeasurementMeasuring the glycemic index or GI rating of a food is conducted under strict conditions, although sampling methods can vary slightly. Portions of GI Food Being TestedTypically, 10 or more volunteers are given a serving of the test-food containing 50 grams of digestible (available) carbohydrate. The actual portion or serving size of each tested food varies according to how much carbohydrate it contains, based on official food composition tables. The smaller the percentage of carbs in the food, the larger the portion needs to be in order to provide the standard 50 gram amount of digestible carbs. Thus in practice, if a food contains a very small proportion of carbohydrate, necessitating a very large test serving size, the test serving is typically scaled down. Blood Tested For GlucoseA sample of blood is then taken from each subject every 15 minutes during the first hour and thereafter every 30 minutes. These blood samples are laboratory-tested for glucose content and the results recorded. Interpretation of ResultsThe glucose level is plotted on a graph and the results are interpreted using a computer program. Test Food Results Compared Against Glucose ResultsThe volunteer's blood-glucose reaction to the food being tested is compared with his/her response to 50g of pure glucose. These comparative tests using pure glucose are typically conducted several times, on several occasions, to provide a mean response. Results AveragedThe average blood sugar response from 8-10 volunteers determines the GI value of that food. GI Rating CategoriesLow GI Food Intermediate GI Food High GI Food Next: What
Determines the GI Value of Carbohydrate in Food?
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