A Glycemic Index Example
Some Starchy Foods Trigger Overeating
Ever wonder why you feel hungry a few hours after eating a big meal? Chances are you ate carbohydrate-containing foods that caused a rapid spike in your blood sugar. This musters extra insulin into the blood. The high insulin, in turn, makes blood sugar crash and suppresses the fat fuels as well. As a result, you get that famished feeling that leads to overeating.
That's what happened in a study of obese teenage boys by researchers at Children's Hospital in Boston and the USDA center in Boston. It's the first solid evidence that carbohydrates with a high glycemic index (GI)—those that are rapidly digested and absorbed—contribute to obesity.
On three separate days at least a week apart, researchers fed the boys breakfast and lunch having either a high, medium or low glycemic index. The boys ate almost twice as much after the high-GI meals compared to the low-GI fare. The high-GI meals induced a sequence of hormonal and metabolic changes that promoted overeating, the researchers reported in the electronic edition of Pediatrics at: http://www.pediatrics.org/cgi/content/full/103/3/e26. They suspect the findings apply to the middle-aged and elderly as well. About one-fifth of U.S. children and one-third of adults are now significantly overweight, despite a significant drop in fat intake over recent years.
Most starchy foods commonly eaten in North America, chiefly refined grain products and potatoes, have a high GI. Moreover, many of the low-fat foods that have flooded grocery shelves are also high in calories. Some starchy foods have GI's up to 50 percent higher than table sugar. Sources of concentrated sugars, such as sodas and fruit juices, also have a high GI. By contrast, vegetables, legumes and fruits generally have a low GI.