You may know about the glycemic index (GI), particularly if you have a disease or condition that affects your blood sugar, like diabetes or hypoglycemia. Or you might have heard the glycemic index diet is good way to lose weight. But is this true? Experts say there's more to the story.
The glycemic index is a food rating system created in 1981 to give people a better idea of which foods contain the types of carbohydrates that cause blood sugar to spike.
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"It is an indicator of how quickly the carbohydrates in an individual food get digested and absorbed. The higher the number, the more quickly and easily the carbs are broken down, turned into glucose, and absorbed into the blood stream," says Daphne Olivier, a dietitian with My Food Coach, via email.
It's ideal to maintain stable blood sugar because frequent spikes can put a person at risk for serious problems, like obesity, heart disease and Type 2 diabetes, among others. "
In a 2008 paper, University of Sydney researchers assigned reliable GI scores to more than 2,480 foods, available online. "Dairy products, legumes, and fruits were found to have a low GI. Breads, breakfast cereals, and rice, including whole grain, were available in both high and low GI versions," the researchers explain in the study.
"We were wanting to give the research community a 'one-stop shop' for all the GI values published in the scientific literature," says University of Sydney nutrition professor Jennie Brand-Miller, in an email interview. "By doing this, we hoped that studies would have greater separation of the high and low GI diets."
So how did they figure out the numbers? Brand-Miller says the researchers fed a 50-gram glucose solution to their study subjects and measured their blood glucose response several times. Then they measured a 50-gram carbohydrate portion of the test food in the same way. They compared the glucose response to the test food with the response to the reference food and expressed the result as a percentage. So, a potato with a GI of 82 means that it would raise a person's blood sugar level 82 percent of what a gram of pure glucose would.
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