To examine the prospective association between glycemic index, glycemic load (GL) of diets and intakes of carbohydrates, sugars, fiber, and the main carbohydrate containing food groups (e.g., soft drinks) with changes in percent body fat, body mass index (BMI), and waist circumference among adolescents.

Design and Methods

Students aged 12 at baseline (n = 856) were examined both in 2004-2005 and 2009-2011. A semiquantitative food frequency questionnaire was administered. Anthropometric parameters were measured and defined using standardized protocols.


After multivariable adjustment, in girls, each 1-SD increase in dietary GL was associated with concurrent 0.77 kg/m2 and 1.45 cm increase in BMI and waist circumference, respectively (both P = 0.01). Conversely, each 1-SD increase in dietary fiber intake was associated with a concurrent 0.44 kg/m2 decrease in mean BMI in girls (P = 0.02) and 1.45 cm decrease in waist circumference in boys (P = 0.002). Girls who consumed soft drinks once or more per day versus those who never/rarely consumed soft drinks, had a 4.45% increase in percent body fat after 5 years (Ptrend = 0.01).


High-GL foods might adversely influence development of body composition, particularly in girls, whereas fiber-rich diets could limit excess weight during adolescence.