GLYCEMIC INDEX AND SATIETY

There is increasing interest in the potential of foods to reduce the drive to eat, including reduced hunger and appetite, and increased fullness and satiety. While these words are often used interchangeably, they are not the same. Hunger is defined as the physiological drive for food, whereas appetite is the psychological desire for food. Fullness is the short-term effect of food and drink and is related to the weight/volume of food and drink in the stomach, whereas satiety is the longer-term feeling that lasts after the initial feeling of fullness subsides. Satiety relates to the digestion and absorption of foods and nutrients further along the gastrointestinal tract (i.e., lower small intestine), including related physiological effects such as changes in hunger hormones (e.g., GLP-1).

As discussed in this month’s Food for thought, the Satiety Index (SI) ranks foods from 0 to 100 compared to the reference food white bread (= 100) and all foods are consumed in 1000 kJ portions (about 250 calories). As regular readers of GI News know, Glycemic Index ranks foods from 0 to 100 compared to the reference food glucose (= 100) and all foods are typically consumed in 50-gram available carbohydrate portions. So, while they are conceptually similar, the two measures are not the same. Perhaps unsurprisingly, based on the limited research conducted using these two methods, there is no simple relationship between Satiety Index and Glycemic Index (GI) in the foods that have been tested. However, there has been considerable research conducted since the mid-1990’s that has investigated the relationship between GI and the drive to eat, independent of the Satiety Index.

In 2014 and again in 2020, Sydney-based researchers conducted systematic literature reviews and meta-analyses of randomised controlled trials investigating the effect of GI on satiety, hunger, fullness, appetite, and prospective food intake. In 2020, 28 studies involving 501 people were eligible for meta-analysis. Low GI foods, meals and diets, compared to medium or high GI comparators, significantly improved all measures of the drive to eat overall (when combined), and also improved subjective measures of the drive to eat (including satiety, appetite, fullness and hunger) overall. For satiety specifically, there was greater improvement than for other subjective measures. Finally, there was a lower food intake in the hours after consumption of a low GI food or meal compared to medium or high GI comparators.

This body of evidence therefore provided compelling evidence that consuming low GI foods, meals and diets improves “satiety”.

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