Index measures speed
Glycemic index ranks a food from 0β100 by how quickly its carbohydrate raises blood glucose compared to pure glucose. Under 55 is low, 56β69 medium, 70+ high.
Load measures reality
Watermelon has a high GI of 76, but a slice contains very little carbohydrate. Glycemic load = GI Γ grams of carbohydrate Γ· 100. That slice has a load of about 5 β negligible. A bagel has a load near 25.
What changes a food's impact
Fat, protein, fibre, acidity and even cooling cooked starches all slow glucose absorption. This is why Syndova Health estimates blood sugar impact from the whole meal, not from one number.