Glycemic Index (GI) vs. Glycemic Load (GL): What's the Difference?
Glycemic index (GI) measures how quickly and how much a food raises blood sugar per gram of carbohydrate, compared to pure glucose. But we don't all eat the same portion sizes, so GI alone can't fully predict how a meal will actually affect your blood sugar. That's where glycemic load (GL) comes in — it multiplies GI by the actual amount of carbs in your serving, giving a more realistic picture of a meal's real-world impact. Enter a food and portion size above to calculate the carbs consumed and the resulting GL.
Why a Low-GI Food Can Still Be Risky in Large Portions
Watermelon has a high GI (76), but since it's only 8g of carbs per 100g, even a decent-sized serving produces a low GL. Spaghetti, on the other hand, has a relatively low GI (49), but a typical 200-300g serving packs enough carbs to push its GL much higher. In other words, choosing foods by GI alone can be misleading — checking GL, which factors in your actual portion, gives a clearer picture for blood sugar management. Portion control matters most for foods like white rice and white bread, which are high in both GI and carb density.
Frequently Asked Questions
Not necessarily. Even a low-GI food can have a high GL if you eat a large portion with a lot of carbs. GI reflects the food's inherent blood sugar response, while GL also accounts for the actual amount eaten.
For a single serving, a GL of 10 or below is considered low, 11-19 is medium, and 20 or above is high. Building meals around low-GL foods helps reduce post-meal blood sugar swings.