What is the glycemic index?

The glycemic index (GI) is based on the speed that food raises blood sugar and insulin levels. This can affect a person’s hunger level and the rate at which fat is deposited into fat storage.

The GI of a food varies depending on whether it’s eaten raw or cooked; if it’s whole, mashed, or ground; whether it’s eaten alone or in combination with other foods, and other factors. For example, the high GI of a white potato goes down dramatically when that potato is eaten as part of a meal containing protein and fat, which slows the sugar from passing into the bloodstream.

Joseph Risser, M.D., M.P.H., Lindora’s Director of Clinical Research, states, “One study I’m familiar with has shown a change in appetite in association with the glycemic index. The purpose of the study was to investigate the effects of dietary glycemic index on energy metabolism and voluntary food intake in obese subjects.

Twelve obese teenage boys were evaluated on three separate occasions using a crossover study protocol. During each trial, subjects consumed identical test meals at breakfast and lunch that had a low, medium, or high GI. Then, the subjects’ food intake was determined in the five-hour period after lunch, and they where told they could eat as much as they liked. Voluntary energy intake (calories consumed) after the high-GI meal was 53 percent greater than after the medium-GI meal and 81 percent greater than after the low-GI meal. The rapid absorption of glucose after consumption of high-GI meals induces a sequence of hormonal and metabolic changes that promote excessive food intake in obese subjects.

To read this interesting research paper, go to http://www.pediatrics.org/cgi/content/full/103/3/e26 The authors stated that before conclusions can be drawn additional studies are needed to examine the relationship between dietary GI and long-term body weight regulation. (Pediatrics, 103: 1-6, 1999). Like so many instances before, glycemic index appears to be a simple theory applied to a complex problem with mixed results. For a list of the GI values, see http://www.mendosa.com/gilists.htm “