A reduced-glycemic load diet in the treatment of adolescent obesity

Arch Pediatr Adolesc Med. 2003 Aug;157(8):773-9. doi: 10.1001/archpedi.157.8.773.


Background: The incidence of type 2 diabetes increases markedly for obese children after puberty. However, the effect of dietary composition on body weight and diabetes risk factors has not been studied in adolescents.

Objective: To compare the effects of an ad libitum, reduced-glycemic load (GL) diet with those of an energy-restricted, reduced-fat diet in obese adolescents.

Design: Randomized control trial consisting of a 6-month intervention and a 6-month follow-up.

Main outcome measures: Body composition (body mass index [BMI; calculated as weight in kilograms divided by the square of height in meters] and fat mass) and insulin resistance (homeostasis model assessment) were measured at 0, 6, and 12 months. Seven-day food diaries were used as a process measure.

Subjects: Sixteen obese adolescents aged 13 to 21 years. Intervention Experimental (reduced-GL) treatment emphasized selection of foods characterized by a low to moderate glycemic index, with 45% to 50% of energy from carbohydrates and 30% to 35% from fat. In contrast, conventional (reduced-fat) treatment emphasized selection of low-fat products, with 55% to 60% of energy from carbohydrates and 25% to 30% from fat.

Results: Fourteen subjects completed the study (7 per group). The GL decreased significantly in the experimental group, and dietary fat decreased significantly in the conventional group (P<.05 for both). At 12 months, mean +/- SEM BMI (-1.3 +/- 0.7 vs 0.7 +/- 0.5; P =.02) and fat mass (-3.0 +/- 1.6 vs 1.8 +/- 1.0 kg; P =.01) had decreased more in the experimental compared with the conventional group, differences that were materially unchanged in an intention-to-treat model (n = 16) (BMI, P =.02; fat mass, P =.01). Insulin resistance as measured by means of homeostasis model assessment increased less in the experimental group during the intervention period (-0.4 +/- 0.9 vs 2.6 +/- 1.2; P =.02). In post hoc analyses, GL was a significant predictor of treatment response among both groups (R2 = 0.51; P =.006), whereas dietary fat was not (R2 = 0.14; P =.22).

Conclusions: An ad libitum reduced-GL diet appears to be a promising alternative to a conventional diet in obese adolescents. Large-scale randomized controlled trials are needed to further evaluate the effectiveness of reduced-GL and -glycemic index diets in the treatment of obesity and prevention of type 2 diabetes.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Blood Glucose / metabolism*
  • Body Composition
  • Body Mass Index
  • Body Weight
  • Diet, Fat-Restricted*
  • Diet, Reducing*
  • Dietary Carbohydrates / administration & dosage*
  • Dietary Fats / administration & dosage*
  • Female
  • Humans
  • Insulin Resistance
  • Linear Models
  • Male
  • Obesity / diet therapy*
  • Obesity / metabolism
  • Regression Analysis
  • Treatment Outcome
  • Weight Loss


  • Blood Glucose
  • Dietary Carbohydrates
  • Dietary Fats