This study investigated the effect of hypohydration produced by exercise and sub-optimal rehydration on appetite and energy intake. Ten males lost ~2% body mass through evening exercise in the heat (35°C). Over the next 13 h, participants were re-fed and either rehydrated (RE: water equal to 175% of body mass loss (BML)) or remained hypohydrated (HYPO: 200 ml water), until the following morning. Urine samples, blood samples and subjective feelings were collected pre-exercise, post-exercise and 13 h post-exercise, with an ad libitum breakfast provided 13 h post-exercise. Total BML at 13 h post-exercise was greater during HYPO (2.8 (0.5)%) than RE (0.5 (0.5)%). Energy intake at the ad libitum breakfast was similar between trials (RE: 4237 (1459) kJ; HYPO: 4612 (1487) kJ; P = 0.436), with no difference in energy consumed in foods (P = 0.600) or drinks (P = 0.147). Total water ingestion at the ad libitum breakfast meal was greater during HYPO (1641 (367) ml) than RE (797 (275) ml) (P < 0.001), with this being explained by increased water intake through fluids (P < 0.001). Thirteen hours post-exercise, participants reported greater thirst (P < 0.001) and lower fullness (P < 0.01) during HYPO. Alterations in hydration status produced by exercise are unlikely to influence post-exercise food intake and consequently other aspects of recovery or adaptation.
Keywords: dehydration; energy balance; fluid balance; hypohydration; recovery.