Glycaemic loadGlycemic load · GL

Glycaemic load is the glycaemic index of a food adjusted for the portion you actually eat. It is calculated by multiplying the index by the grams of available carbohydrate in that portion and dividing by a hundred, which converts a laboratory ranking into something applicable to a plate.

It exists because the index alone is misleading. Index is measured on the quantity of a food containing 50 g of carbohydrate, which for watermelon is an unreasonable amount of watermelon. Watermelon therefore has a high index and a very low load, and treating the two as interchangeable produces exactly the wrong advice.

It matters most where portion size varies enormously between foods, which is most of the time. A small amount of a high index food and a large amount of a low index one can produce similar glucose responses.

It shares the index's other limitations. Ripeness, cooking, cooling, processing and what else is on the plate all change the response, and individual variation is substantial: continuous monitoring studies find people responding differently to identical meals.

Its practical value is in managing diabetes, where lower load diets have modest evidence for improving glucose control. For people without diabetes, a post meal glucose rise is normal physiology rather than damage, and the evidence for chasing low load eating is much weaker.

In practice what it mostly tracks is fibre, processing and portion size, all of which can be addressed directly without arithmetic. Whole foods with their fibre intact, eaten in sensible amounts alongside protein, produce gentler curves without a lookup table.

Our CGM metrics calculator interprets sensor data for people who have it, and our macro calculator handles the totals for everyone else.