Effect of Exercise Duration on Subsequent Appetite and Energy Intake in Obese Adolescent Girls

There is a growing interest regarding the effect of exercise on appetite and energy intake in youth. While the role of exercise intensity has been a primary focus of study, the effect of exercise duration on subsequent food intake has not been fully examined in obese adolescents. On three separate mornings in a randomly assigned order, obese adolescent girls (n = 20) aged 12-15 years old were asked to perform a rest session (control, CON) or two cycling sessions for 20 (EX20) or 40 min (EX40) set at their ventilatory threshold. Absolute and relative energy intake were measured from an ad libitum lunch meal 30 min after rest or exercise and appetite feelings assessed using visual analogue scales throughout the day. Hunger, satiety, and prospective food consumption were not significantly different between conditions. Absolute energy intake (kcal) did not differ between conditions, while relative energy intake on EX40 (571 ± 381 kcal) was significantly lower than during CON (702 ± 320 kcal; p < .05) and EX20 (736 ± 457 kcal; p < .05). Fat ingestion (in grams) was significantly lower on CON (7.8 ± 3.2 g) compared with EX20 (10.3 ± 4.6 g; p < .01). Protein intake (in grams) was higher on EX20 (37.0 ± 16.6 g) compared with both CON (29.5 ± 11.7 g; p < .01) and EX40 (33.1 ± 10.9 g; p < .05). However, the percentage of total energy derived from each macronutrient was not different between conditions. Obese adolescent girls do not compensate for an acute bout of exercise set at their ventilatory threshold by increasing energy intake, regardless of the exercise duration.