Introduction et But de l’étude. – Acute exercise intensity can affect energy expenditure and energy intake, the result on 24 h energy balance being of major interest for obesity management and weight loss. The aim of the study was to examine whether intensive vs. moderate or sedentary exercise can decrease spontaneous energy intake and thus induce negative 24 h energy balance in obese adolescents.

Matériel et Méthodes. – 15 obese pubertal adolescents aged 14.4±1.5y participated to a randomized cross-over study in calorimetric chambers. Standard breakfast was given before entry into the calorimetric chambres. Its energy content matched the expected energy expenditure during the morning so that energy balance was neutral at 12 a.m. Two isoenergetic exercises (intensive 75 % VO₂max vs. moderate 40 % VO₂max) and sedentary sessions were randomly performed at 11 a.m. Spontaneous energy intake (ad libitum lunch, dinner, breakfast) and physical activity were assessed from 12 a.m. to next morning 8 a.m. Subjective appetite sensation was evaluated using Visual Analogue Scales.

Résultats. – Total energy intake at lunch and dinner was significantly reduced by 31% after intensive exercise in comparison to moderate exercise and sedentary sessions (p<0,01). Energy intake at dinner was the most affected after intensive exercise. By contrast, energy intake the next morning at breakfast was similar between all conditions. Energy balance was significantly reduced after intensive exercise in comparison with moderate exercise and sedentary sessions (p<0,05). Subjective appetite rates were similar between sessions.

Conclusion. – By dually affecting energy expenditure and energy intake, intensive exercise favors a negative energy balance in comparison with moderate exercise and sedentary conditions. This is associated with no changes in appetite sensations, suggesting that adolescents are not at risk of food frustration.