There is a lot of information available about the glycemic index (GI) and most of what you read will indicate that a low GI diet has various advantages to one’s health. But is it as black and white as it’s made out to be? Does it just come down to low GI being good and high GI being bad?

First, what is glycemic index? In simple terms, the glycemic index is a ranking system of 0-100 that is measured by any one particular foods ability to raise blood sugar levels after eating. It was designed to help in situations which glucose tolerance is impaired, like diabetes, to easier control their blood sugar levels. Large increases in blood sugar levels are also believed to be part of controlling hunger and satiety. Other purposes are to prevent chronic western diseases and controlling bodyweight better in a low-GI compared to a high-GI diet.

To measure it, the subject consumes a food that contains a fixed amount of carbohydrates; usually 50g. This means that if pure sugar is eaten, the volume is much smaller than if carrots, for example, are eaten. Foods that are considered to have a high GI are digested and absorbed rapidly and raise blood sugar quickly. Low-GI on the other hand, is supposed to have a slower digestion and absorption rate, thus maintain more stable blood sugar levels. White bread or plain sugar is most often used as a reference food with a score of 100.

Foods low in GI is thus supposed to be superior in terms of controlling hunger, ad libitum energy intake, body composition and weight, and overall health.

For a list of different carb sources and their glycemic index, see table 1 here. Note that this is food eaten in isolation – not something that happens often in real life.

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