Breakfast omission might be an effective means of reducing daily energy intake but may impair performance later that day, even after consuming lunch.

Effects of exercise on subsequent energy intake are well documented, but whether pre-exercise energy intake is affected by future planned exercise is unknown. This study investigated the effect of planned late-afternoon exercise on appetite and energy intake before (breakfast and lunch) and after (evening meal/snacks) exercise. Methods: Twenty healthy, active participants (10 male; age 23 ± 5 y, BMI 23.7 ± 3.2 kg/m 2 , VO2peak 44.1 ± 5.4 ml/kg/min) completed randomised, counterbalanced exercise (EX) and resting (REST) trials.After trial notification, participants were provided ad libitum breakfast (0800 h) and lunch (1200 h) in the laboratory, before completing 1-h exercise (30 min cycling, 30 min running) at 75-80% maximal HR (EX; 2661 ± 783 kJ) or 1-h supine rest (REST; 310 ± 58 kJ) 3-h postlunch. Participants were provided a food pack (pasta meal/snacks) for consumption postexercise (outside laboratory). Appetite was measured regularly and meal and 24-hour energy intake quantified. Results: Ad-libitum energy intake was greater during EX at lunch (EX 3450 ± 1049 kJ; REST 3103 ± 927 kJ; P=0.004), but similar between trials at breakfast (EX 2656 ± 1291 kJ; REST 2484 ± 1156 kJ; P=0.648) and dinner (EX 6249 ± 2216 kJ; REST 6240 ± 2585 kJ; P=0.784). Total 24-hour energy intake was similar between trials (P=0.388), meaning relative energy intake (24-h energy intake minus EX/REST energy expenditure), was reduced during EX (EX 9694 ± 3313 kJ; REST 11517 ± 4023 kJ; P=0.004). Conclusion: Energy intake appears to be increased in anticipation of, rather than in response to, aerobic exercise, but the increase was insufficient to compensate for energy expened during exercise, meaning aerobic exercise reduced energy balance relative to rest.

In many situations, meals are planned (i.e. what and how much) before they are eaten, but how exercise influences this planning is unknown. Therefore, this study investigated whether anticipation of an exercise session alters food intake planned for post-exercise. Forty (16 male) regular exercisers (mean ± SD; age 23.3 ± 5.6 y, BMI 22.7 ± 3.3 kg/m 2 , body fat 25.6 ± 7.6%) completed the study. Subjects arrived ≥3 h post-prandial and were given two hypothetical scenarios for the following day: 1) morning rest (REST), or 2) morning rest with the addition of 1 h of hard aerobic exercise at 10:00-11:00 (EXERCISE). For each scenario subjects had to plan their lunch, to consume at 12:00, by serving themselves cheesy tomato pasta and chocolate buttons. Scenarios were counterbalanced and separated by 5 minutes and foods were not consumed. EXERCISE increased total energy served by 24% (EXERCISE 3308 ± 1217 kJ; REST 2663 ± 924 kJ; P<0.001), with increases in energy served from both pasta (+25%; P<0.001) and chocolate buttons (+20%; P=0.024). These results suggest aerobic exercise increases planned post-exercise energy intake, if a meal is planned in advance of exercise. Future research should examine the impact of exercise on meal planning at other meals, as well as how this behaviour impacts weight loss with exercise training.

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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.