Insulin resistance is a known sequela of obesity; however, the relationship of insulin resistance to future weight gain remains unclear. In several studies, insulin resistance has been associated with weight stabilization. For the most part, this relationship has been found in adults who are overweight. To evaluate the relationship of insulin resistance to future fat accumulation in pubertal children, a 3-yr prospective study was carried out. Insulin sensitivity (Si) was determined by Bergman's minimal model in 111 healthy children, aged 9.7-14.5 yr. All children were Tanner stage II or III pubertal development at baseline. Body composition was assessed by body mass index, skinfold thickness, hydrodensitometry, and bioelectric impedance analysis at baseline and annually thereafter for an additional 3 yr. A repeated-measures analysis showed that the change in percentage body fat estimated from skinfold thickness [%BF(SF)] over time changed with increasing Si (P < 0.0001). Si was divided into tertiles for each gender, with the lowest tertile representing the most insulin-resistant children. For girls, those in the lowest tertile maintained their %BF(SF) over 3 yr, whereas those girls in the middle and upper tertile had an increase in their %BF(SF). For boys, those in the lowest tertile showed a decrease in their %BF(SF), whereas those boys in the middle and upper tertile maintained their %BF(SF). These results suggest that during puberty, children who are more insulin resistant have decreased sc fat gain.