Energy intake (EI) and energy expenditure (EE) should not be considered independent entities, but more an inter-connected system. With increased physical activity and reduced snacking initiatives as prevalent Public Health measures, any changes to subsequent EI from these recommendations should be monitored. The aim of this study was to investigate changes in acute EI and appetite over four conditions: (1) a control condition with no snack and no exercise (CON); (2) a snack condition (+1 MJ; SK); (3) a moderate-intensity cycling exercise condition (-1 MJ; EX); and finally (4) both snack and exercise condition (+1 MJ, -1 MJ; EXSK). Acute changes in appetite (visual analogue scale) and lunchtime EI (ad libitum pizza meal) were recorded in twenty boys and eighteen girls (12-13 years). Lunch EI was not significantly different between conditions or sexes (P>0·05). Relative EI was calculated, where the energy manipulation (+1 MJ from the snack or -1 MJ from the exercise) was added to lunchtime EI. Relative EI indicated no significant differences between the sexes (P>0·05); however, in the EX condition, relative EI was significantly lower (P<0·001) compared with all other conditions. Appetite increased significantly over time (P<0·001) and was significantly higher in the CON and EX conditions compared with the SK and EXSK conditions. No significant sex differences were found between conditions. When aiming to evoke an acute energy deficit, increasing EE created a significantly larger relative energy deficit than the removal of the mid-morning snack. Sex was not a confounder to influence EI or appetite between any of the conditions.
Keywords: EE energy expenditure; EI energy intake; Eating behaviours; Mood; Preload meals; Sex differences.