Glycemic Index
Definition
The Glycemic Index (GI) is a numerical scale (0–100) that ranks carbohydrate-containing foods by how quickly they raise blood glucose levels after consumption compared to pure glucose (GI = 100). Low-GI foods (55 or less) include most vegetables, legumes, whole grains, and nuts — they cause a slow, steady rise in blood sugar. Medium-GI foods (56–69) include whole wheat bread and brown rice. High-GI foods (70+) include white bread, white rice, sugary drinks, and potatoes — they cause rapid blood sugar spikes. Low-GI diets are associated with better blood sugar control, sustained energy, and reduced risk of type 2 diabetes.
Why is Glycemic Index Important?
Understanding Glycemic Index empowers you to take control of your personal health and wellness. Whether you are tracking body composition, planning nutrition, or evaluating fitness metrics, this concept provides the foundation for making informed health decisions backed by science.
Our health calculators make these metrics accessible and easy to compute, giving you instant, evidence-based results so you can focus on achieving your wellness goals rather than crunching numbers.
What is the Glycemic Index?
The Glycemic Index (GI) is a scale from 0 to 100 that ranks carbohydrate-containing foods by how quickly they raise blood glucose levels after eating. The reference point is pure glucose, which has a GI of 100. Foods with a lower GI are digested and absorbed more slowly, producing a gradual rise in blood sugar.
GI Classification
| Category | GI Range | Blood Sugar Effect | Examples |
|---|---|---|---|
| Low GI | 55 or less | Slow, steady rise | Most vegetables, legumes, nuts, whole grains |
| Medium GI | 56–69 | Moderate rise | Whole wheat bread, brown rice, sweet potato |
| High GI | 70 or more | Rapid spike | White bread, white rice, sugary drinks, cornflakes |
GI of Common US Foods
| Food | GI | Category |
|---|---|---|
| White bread | 75 | High |
| Whole wheat bread | 69 | Medium |
| White rice | 73 | High |
| Brown rice | 68 | Medium |
| Oatmeal (rolled oats) | 55 | Low |
| Sweet potato | 63 | Medium |
| Russet potato (baked) | 85 | High |
| Apple | 36 | Low |
| Banana (ripe) | 51 | Low |
| Watermelon | 76 | High |
| Lentils | 32 | Low |
| Chickpeas | 28 | Low |
| Corn flakes | 81 | High |
| Coca-Cola | 63 | Medium |
| Snickers bar | 55 | Low (fat slows absorption) |
Glycemic Index vs Glycemic Load
| Metric | GI | GL (Glycemic Load) |
|---|---|---|
| Measures | Speed of blood sugar rise | Total blood sugar impact per serving |
| Accounts for portion | No — tested with 50g of carbs | Yes — includes actual serving size |
| Example: Watermelon | 76 (high GI) | 5 (low GL — has few carbs per serving) |
| More practical? | Useful for food comparison | Better for real-world meal planning |