Purpose We previously observed increased energy intake (EI) at the meal before planned afternoon exercise, but the proximity of the meal to exercise might have reduced the scale of the pre-exercise anticipatory eating. Therefore, this study examined EI in the 24 h before fasted morning exercise. Methods Fourteen males, experienced with gym-based aerobic exercise (age 25 ± 5 years, BMI 23.8 ± 2.5 kg/m2), completed counterbalanced exercise (EX) and resting (REST) trials. On day 1, subjects were told the following morning’s activity (EX/REST), before eating ad-libitum laboratory-based breakfast and lunch meals and a home-based afternoon/evening food pack. The following morning, subjects completed 30-min cycling and 30-min running (EX; 3274 ± 278 kJ) or 60-min supine rest (REST; 311 ± 34 kJ) fasted. Appetite was measured periodically, and EI quantified. Results Afternoon/evening EI (EX 7371 ± 2176 kJ; REST 6437 ± 2070 kJ; P = 0.017) and total 24-h EI (EX 14,055 ± 3672 kJ; REST 12,718 ± 3379 kJ; P = 0.011) were greater during EX, with no difference between trials at breakfast (P = 0.761) or lunch (P = 0.071). Relative EI (EI minus energy expended through EX/REST) was lower in EX (EX 10,781 ± 3539 kJ; REST 12,407 ± 3385 kJ; P = 0.004). Conclusion This study suggests planned fasted aerobic exercise increases EI during the preceding afternoon/evening, precipitating a ~ 10% increase in EI in the preceding 24-h. However, this increase did not fully compensate for energy expended during exercise; meaning exercise induced an acute negative energy balance.

The effect of an acute aerobic exercise session on subsequent energy intake has been well investigated, with studies generally reporting little difference in post-exercise energy intake compared to a resting trial (1). Despite this, little research has examined how an impending exercise session influences energy intake before the exercise session, which is surprising as exercise is rarely spontaneous, and exercisers may alter their energy or nutrient intake in anticipation of exercise. Therefore, this study examined energy and nutrient intake on the day before a fasted morning exercise session. Six healthy, recreationally active males, who performed cardiovascular exercise ≥3 times/ week (age 23 (6) y, BMI 24.2 (2.0) kg/m 2 , body fat 17.7 (2.3) %, VO 2 peak 49.1 (2.2) mL/kg/min) completed exercise (EX) and resting (REST) trials in a randomised, counterbalanced order, after completing a full familiarisation with the EX trial. On the morning of day 1, subjects attended the laboratory and were notified whether they would perform exercise or rest the following morning, before having access to buffet-style ad-libitum breakfast (08:00) and lunch (12:00) meals and being provided with an ad-libitum food bag for the evening (17:00-23:00). The next morning (day 2), subjects came to the laboratory at 08:00, and completed a 60 min exercise/ rest session in a fasted state. Thirty min after exercise/ rest, subjects were given access to an ad-libitum buffet breakfast. Subjective appetite sensations were measured periodically, with individual meal and 24 h energy intake quantified. Energy expended during the 60 min exercise/ rest was greater during EX (EX 3103 (255) kJ; REST 319 (34) kJ; P < 0.05). Energy intake was similar between trials at breakfast on both days (day 1: