Glycaemic load (GL)
A measure that combines a food's glycaemic index with the amount of carbohydrate actually eaten in a given portion.
Glycaemic load is calculated as follows: GL = (GI × grams of carbohydrate in the portion) / 100. For example, a white baguette has a GI of 70 per 100 g, but it provides about 57 g of carbohydrate, so GL = (70 × 57) / 100 = 39.9, a very high GL.
It is a more precise tool than GI in real-life nutrition because it reflects what you actually eat. Watermelon has a medium GI (75), but because it is full of water, a portion contains little carbohydrate, hence a moderate GL.
A fresh angle: GL is critical for insulin-dependent diabetics, who adjust their dose according to this parameter. But in general nutrition it is under-used. Many people think a « low-GI » food can be eaten without limit, which is false. A low-GI bar eaten in a triple portion can outdo a higher-GI food in a normal portion in terms of real glycaemic impact.
To lower the GL of a meal, you do not just add a salad (little effect) but fibre, protein and fat: fibre slows carbohydrate absorption, while protein and fat create a slower flow of energy. This is why a complete meal manages blood sugar better than a food eaten on its own.