High
Glycemic Index Foods
and Overeating in Obese Individuals
A recent study
suggests that dietary fat may not be the principal cause of obesity.
The researchers, led by David S. Ludwig, M.D., Ph.D.,* the Director
of the Obesity Program at Children’s Hospital in Boston,
focused instead on glycemic index (GI), which is a measure of
the effect foods have on blood-glucose level after they are eaten.
Ludwig defines high-GI foods as those “that are rapidly digested
and absorbed or transformed metabolically into glucose.”
These include refined starchy foods (such as bread, cereal, pasta)
and table sugar. By contrast, low-GI foods comprise most vegetables,
legumes, and fruits.
In their study of 12 obese adolescent males, the researchers found
that after eating high-GI meals, the subjects were hungrier and
ate again sooner: voluntary food intake was 53 percent greater
than after a medium-GI meal, and 81 percent greater than after
a low-GI meal.
The researchers concluded that the hormonal and metabolic changes
that occurred in those who had eaten high-GI meals—as their
bodies more readily absorbed glucose—led them to eat excessively.
They also reported greater hunger sooner after eating than those
who had eaten medium- and low-GI meals. The researchers acknowledge
that the study charted only the acute effects of low-GI meals:
“The effectiveness of a low-GI diet in promoting long-term
weight loss is unknown.” More studies are needed to determine
the role of GI and other factors in eating and in weight gain.
“Nevertheless,” said Ludwig, “this study suggests
possible advantages for treating obesity with a diet abundant
in vegetables, legumes, and fruits; low in high-GI carbohydrates;
and moderate in protein and fats.” Ludwig also found that
reducing GI in the diet may improve serum lipids and decrease
the risk of type 2 diabetes.
Ludwig’s study, published in the March 1999 issue of Pediatrics,
is available through the American Academy of Pediatrics, 141 Northwest
Point Blvd., Elk Grove Village, IL 60007-1098; phone: (847) 981-7903;
and can be found on the Web at http://www.pediatrics.org.
* Ludwig and
coauthor Susan Roberts, Ph.D., of the Jean Mayer USDA Human Nutrition
Research Center on Aging at Tufts University, are grantees of the
National Institute of Diabetes and Digestive and Kidney Diseases.
WIN Notes
Linda Bren, Editor
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