Purpose: Chronic exercise programmes can induce adaptive compensatory behavioural 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, 13-year-old adolescent girls completed a twelve-week supervised exercise intervention (EX). Twelve body size matched girls comprised the non-exercise control group (CON). Body composition, EI, free-living energy expenditure (EE) and peak oxygen uptake (V ̇O_2) were measured repeatedly over the intervention. Results: Laboratory EI (EX: 9027, 9610, 9243 kJd-1 and CON: 9953, 9770, 10052 kJd-1 at 0, 12 and 18 weeks respectively) (ES = 0.26, P = 0.46) and free living EI (EX: 7288, 6412, 5273, 4916 kJd-1 and CON: 7227, 7128, 6470, 6337 kJd-1 at 0, 6, 12 and 18 weeks respectively) (ES ≤ 0.26, P = 0.90) 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 (13295 vs. 12115 kJd-1, ES ≥ 0.88, P ≥ 0.16), but no significant condition by time interactions were observed (P ≥ 0.17). Conclusion: The current findings indicate that compensatory changes in EI and EE behaviours did not occur at a group level within a small cohort of adolescent girls. However, analysis at the individual level highlights large inter-individual variability in behaviours, which suggest a larger study may be prudent to extend this initial exploratory research.