Glycemic Index (GI)
A measure of how fast a food raises blood glucose — one of the most practically useful tools in nutrition.
— Definition
Glycemic Index (GI) ranks foods on a 0–100 scale based on how quickly they raise blood glucose compared to pure glucose (GI 100). Low GI is <55, medium 55–69, high 70+.
— In Detail
GI is measured by feeding 10+ healthy volunteers a portion of the food containing 50g of available carbohydrate, then measuring blood glucose every 15–30 minutes for 2 hours. The area under the resulting curve is compared to the same person's response to 50g of pure glucose. The score is averaged across all participants. Factors that reduce GI: fibre, protein, fat, acidity, intact grain structure, resistant starch, and refrigeration after cooking. Factors that raise GI: milling, puffing, extrusion, overcooking, and ripeness.
— Why It Matters
Most traditional Indian staples — heirloom millets, ancient wheats, indigenous legumes — have dramatically lower GI than their modern replacements. Switching from polished white rice (GI 72) to barnyard millet (GI 43) can reduce a meal's glucose spike by 40%. For the 77 million Indians with diabetes and hundreds of millions with insulin resistance, this difference is clinical, not academic.
— Related Terms
— See in Field Guide
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