GLOSSARY

Glycemic Load of Foods Table

Calculated examples use specific Sydney GI values and stated available carbohydrate quantities; the carbohydrate amount is an illustrative comparison basis.

Glycemic Load (GL) combines GI's relative response with the available-carbohydrate quantity in a portion. Unlike GI it changes with portion size, but remains an estimate rather than a measured personal glucose curve.

Doubling portion carbohydrate doubles calculated GL if GI is held constant, although the actual response is not necessarily exactly linear. A modest fruit portion cannot be equated with a large sweet drink from GI alone. Quantity belongs in the comparison.

Glycaemic load is estimated as GI multiplied by grams of available carbohydrate in the portion, divided by 100. A hypothetical GI of 60 and a portion containing 25 grams gives a GL of 15. This combines test response and portion size, but does not directly measure an individual's blood glucose.

In standard testing, glycaemic index compares the incremental area under the glucose curve after a specified available-carbohydrate dose, usually 50 grams, with a reference food. Glucose is 100 on the common scale. The result is a group-based test value, not an exact prediction for every person and portion.

On the glucose-equals-100 scale, GI values of 55 or below are low and values of 70 or above are high, with intermediate values classed as medium. These boundaries do not specify a portion's carbohydrate amount. A value for one bread or rice preparation should not be assigned to all varieties and cooking methods.

Actual portion size determines how much of a food's components is consumed. If the labelled serving differs from the portion eaten, calculations must be adjusted to the actual amount. Accompanying oils, sauces, and drinks also matter when interpreting a meal.

Fat, protein, fibre, acidity and food structure can modify the post-meal response. A mixed meal does not behave exactly like an isolated ingredient, and adding paper-based indices cannot determine the actual curve with certainty. Sporting decisions also require total carbohydrate and time before activity alongside these properties.

Glucose responses depend on portion size, previous meals, recent activity, measurement timing and individual characteristics. Two people may respond differently to similar food. A transient peak alone does not rate the whole diet, diagnose disease or quantify glycogen stores; context and reproducibility matter when interpreting the observation.

Table references: University of Sydney · 1 · University of Sydney · 2