Swimming may stimulate appetite and food intake but empirical data are lacking. This study examined appetite, food intake, and plasma acylated ghrelin responses to swimming. Fourteen healthy males completed a swimming trial and a control trial in a random order. Sixty min after breakfast participants swam for 60？min and then rested for six hours. Participants rested throughout the control trial. During trials appetite was measured at 30？min intervals and acylated ghrelin was assessed periodically (0, 1, 2, 3, 4, 6, and 7.5 h. ). Appetite was suppressed during exercise before increasing in the hours after. Acylated ghrelin was suppressed during exercise. Swimming did not alter energy or macronutrient intake assessed at buffet meals (total trial energy intake: control 9161？kJ, swimming 9749？kJ). These findings suggest that swimming stimulates appetite but indicate that acylated ghrelin and food intake are resistant to change in the hours afterwards. 1. Introduction Regular physical activity is important for the maintenance of body weight and its composition within a healthy range [1, 2]. All forms of physical activity can contribute to successful energy balance by increasing daily energy expenditure. Swimming is an attractive mode of physical activity due to the reduced musculoskeletal and thermoregulatory stresses (i.e., elevation in body temperature) imposed in comparison with other land-based activities such as running and cycling. Swimming may therefore offer an appealing form of physical activity for individuals seeking to prevent weight gain and/or to maintain a reduced body weight after successful weight loss. Despite the attractiveness of swimming as a mode of physical activity, the ability of swimming to favourably influence body weight and body composition remains contentious. In obese individuals research has shown that swimming may not induce body weight and fat loss [3, 4] whereas walking and cycling interventions of similar intensity and duration do [3]. Considering the heightened energy output elicited by all forms of exertion the most logical explanation for these findings is that swimming stimulates a compensatory increase in energy intake [5]. This notion is consistent with anecdotal reports of swimming stimulating appetite. Specifically, it has been stated that individuals often feel like “eating a horse” after an acute bout of swimming [6]. This suggestion is consistent with empirical research which has described elevations in energy intake after cycling-based exercise performed on a modified ergometer in cold water [5, 7]. Despite
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