Study: Obese Teens Fare Better on Reduced Glycemic Load Diet

A reduced glycemic load diet is better than a reduced fat diet in helping obese adolescents lose weight and keep it off, according to a study reported in the August issue of the Archives of Pediatric and Adolescent Medicine.

Glycemic index measures how fast a particular food is likely to raise one's blood sugar. Glycemic load takes into account a food's glycemic index as well as the amount of carbohydrates per serving it contains.

Researchers at Children's Hospital in Boston experimented with how 14 obese adolescents between the ages of 13 to 21 years would respond on a reduced glycemic load diet compared to a conventional reduced fat diet.

The reduced glycemic load diet consisted of 45 percent to 50 percent carbohydrates and 30 percent to 35 percent fat and emphasized such food as nonstarchy vegetables, fruits, legumes, nuts and diary products. In contrast, the conventional reduced-fat diet consisted of more carbohydrates, 55 percent to 60 percent, and less fat, 25 percent to 30 percent.

The reduced glycemic load dieters were instructed to balance consumption of carbohydrates with protein and fat at every meal and snack. The dieters had great flexibility in choosing their food in light of preliminary evidence suggesting that greater satiety and decreased voluntary energy intake occurs among children and adolescents on such diets.

The reduced-fat diet was prescribed with emphasis on limiting dietary fat intake and increasing the intake of grains, vegetables and fruits.

Body mass index and fat mass decreased significantly more in the reduced glycemic load group than the reduced-fat group at the end of the study with no weight regain in the former group between six and 12 months after the study.

The researchers attributed the weight loss in the reduced glycemic load dieters to their feelings of being less hungry and/or feeling more full after meals and snacks than the reduced-fat group.

Not surprisingly, the researchers found that motivation varied widely among all the adolescents involved. "Although most participating parents were well intentioned, not all provided adequate support with regard to provision of recommended foods, transportation to counseling sessions and encouragement," the researchers noted.

The researchers added that study participants often enjoyed socializing with peers at food courts and fast-food restaurants where they were challenged to make choices that conformed to their diets.

"Research is needed to develop novel strategies for motivating obese adolescents to change their eating behaviors and for motivating parents to provide appropriate support in environments that pose challenges to adherence," the researchers concluded.

Other sources: Archives of Pediatric & Adolescent Medicine 2003;157:773-779