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Purpose: Chronic exercise programs can induce adaptive compensatory behavioral responses through increased energy intake (EI) and/or decreased free-living physical activity in adults. These responses can negate the benefits of an exercise-induced energy deficit; however, it is unclear whether young people experience similar responses. This study examined whether exercise-induced compensation occurs in adolescent girls. Methods: Twenty-three adolescent girls, heterogeneous for weight status, completed the study. Eleven adolescent girls aged 13 years completed a 12-week supervised exercise intervention (EX). Twelve body size–matched girls comprised the nonexercise control group (CON). Body composition, EI, free-living energy expenditure (EE), and peak oxygen uptake ( $\dot{\mathrm{V}}{\mathrm{O}}_2$ ) were measured repeatedly over the intervention. Results: Laboratory EI (EX: 9027, 9610, and 9243 kJ·d⁻¹ and CON: 9953, 9770, and 10,052 kJ·d⁻¹ at 0, 12, and 18 wk, respectively; effect size [ES] = 0.26, P = .46) and free-living EI (EX: 7288, 6412, and 5273, 4916 kJ·d⁻¹ and CON: 7227, 7128, and 6470, 6337 kJ·d⁻¹ at 0, 6, 12, and 18 wk, respectively; ES ≤ 0.26, P = .90) did not change significantly over time and were similar between groups across the duration of the study. Free-living EE was higher in EX than CON (13,295 vs 12,115 kJ·d⁻¹, ES ≥ 0.88, P ≥ .16), but no significant condition by time interactions were observed (P ≥ .17). Conclusion: The current findings indicate that compensatory changes in EI and EE behaviors did not occur at a group level within a small cohort of adolescent girls. However, analysis at the individual level highlights large interindividual variability in behaviors, which suggests a larger study may be prudent to extend this initial exploratory research.