The Glycemic Index (GI) is a 0-100 scale measuring how quickly a food raises blood sugar vs pure glucose. Low GI (<55) = slow, steady rise. Medium GI (55-70) = moderate rise. High GI (>70) = fast spike. Developed at the University of Toronto in 1981 by Dr. David Jenkins to help diabetics manage blood sugar through food.
| Food | GI Score | Category | Blood Sugar Impact |
|---|---|---|---|
| Glucose (reference) | 100 | Sugar | 🔴 Extreme spike |
| White bread | 75 | Grain | 🔴 High spike |
| Instant oatmeal | 83 | Grain | 🔴 High spike |
| White rice | 72 | Grain | 🔴 High spike |
| Banana (ripe) | 51 | Fruit | 🟡 Moderate |
| Brown rice | 50 | Grain | 🟡 Moderate |
| Steel-cut oats | 42 | Grain | 🟢 Low |
| Sweet potato | 44 | Vegetable | 🟢 Low |
| Apple | 36 | Fruit | 🟢 Low |
| Lentils | 32 | Legume | 🟢 Very low |
| Chickpeas | 28 | Legume | 🟢 Very low |
| Broccoli | 10 | Vegetable | 🟢 Negligible |
The Glycemic Index (GI) is a scale from 0-100 that measures how quickly a food raises blood sugar compared to pure glucose. Low GI is under 55, medium is 55-70, and high GI is above 70.
GI measures how fast a food raises blood sugar per gram of carbohydrate. Glycemic Load (GL) accounts for portion size. GL = GI × carbs per serving ÷ 100. Watermelon has a high GI of 80 but a low GL of 5 per serving because it's mostly water.
Low GI foods (under 55): lentils (32), chickpeas (28), sweet potato (44), apple (36), Greek yogurt (11), brown rice (50), steel-cut oats (42), most non-starchy vegetables, and all nuts and seeds.
Highest GI foods: glucose (100), white bread (75), instant mashed potatoes (87), white rice (72), instant oatmeal (83), cornflakes (81), watermelon (80), and most refined carbohydrates and sugary foods.
Yes significantly. Cooking pasta al dente (firm) has a lower GI than overcooked soft pasta. Cooling and reheating cooked starchy foods (rice, potatoes) increases resistant starch and lowers GI by 10-15 points. Riper fruit has a higher GI than unripe.
Evidence is mixed. Low GI eating can improve satiety and reduce hunger between meals, potentially lowering total calorie intake. However, total calories remain the primary driver of weight loss. Low GI eating is most beneficial for diabetes management and blood sugar control.
GI is most important for: people with type 2 diabetes, prediabetes, or insulin resistance, people with PCOS, anyone experiencing energy crashes after meals, athletes managing performance nutrition, and people who experience brain fog or fatigue after eating.
Yes. FoodIdentifier's Blood Sugar Predictor scans any meal photo and shows an estimated glycemic impact, GI score, and blood sugar spike risk. Free, no sign-up required.