SugarHigh Team
Glycemic Index vs Glycemic Load: The Difference, With Examples
Short answer: glycemic index (GI) compares how quickly the carbohydrate in a food raises blood glucose against pure glucose (100). Glycemic load (GL) multiplies GI by the carbohydrate in a portion, so it reflects how much you actually eat (Linus Pauling Institute).
The formula
GL = GI × grams of available carbohydrate in the portion / 100.
The bands
| Low | Medium | High | |
|---|---|---|---|
| GI (Diabetes Canada) | 55 or less | 56 to 69 | 70 or more |
| GL per serving (Linus Pauling Institute) | 10 or less | 11 to 19 | 20 or more |
Two examples that show the difference
| Food | GI (Atkinson 2008) | Net carbs / 100 g (USDA) | GL / 100 g, calculated |
|---|---|---|---|
| Watermelon, raw | 76 (high) | 7.2 g (FDC 167765) | 5 (low) |
| Dates, raw / Medjool | 42 (low) | 68.3 g (FDC 168191) | 29 (high) |
A published example: a 150 g banana has GI 47, 29.4 g available carbs and GL 14 (glycemicindex.com). © GI News, University of Sydney.
Which is better to use?
Neither alone. GI helps compare similar foods (rolled oat porridge 55 vs instant oat porridge 79, Atkinson 2008). GL helps judge a real portion.
FAQ
Is GL more useful than GI?
They answer different questions; use both.
Can a high GI food have a low GL?
Yes, watermelon.
Does cooking change GI?
Yes, for example boiled potato 78 vs instant mash 87 (Atkinson 2008).
