Definition
Glycemic index (GI) is a number from 0 to 100 that ranks how quickly a carbohydrate-containing food may raise blood glucose, relative to the same amount of pure glucose (GI 100). Foods with a low GI tend to produce a slower, flatter rise; foods with a high GI tend to produce a faster, steeper rise.
The Standard Ranges
- Low GI: 55 or less — lentils, apples, Greek yogurt, most legumes
- Medium GI: 56–69 — whole wheat bread, sweet potato, pineapple
- High GI: 70 or more — white bread, cornflakes, white rice, watermelon
What GI Does NOT Tell You
GI is measured on a fixed portion of available carbohydrate (usually 50 g), not on a normal serving. That is the key limitation: a high-GI food eaten in a small amount can produce less glucose than a low-GI food eaten in a large amount. This is why GI is always read together with glycemic load and portion size.
Important Caveats
Published GI values are averages from tests on small groups, and the value of a specific food varies with variety, ripeness, cooking method, processing and testing conditions. DMSafeHaven therefore reports GI values together with their published range and an evidence level — a single fixed number overstates the science. See the food database and methodology.
In short: GI describes how quickly a carbohydrate food tends to raise blood glucose relative to a reference. It is one input — not the whole answer — to how a food affects you.