Hard exercise may temporarily kill your appetite, but hunger will catch up with you within one to two hours. Temperature control regulates appetite to some extent. Therefore, if you feel hot after a hard workout, you may experience a temporary drop in appetite. But if you’re chilled, such as after swimming, you may feel ravenous.
The effect of exercise on appetite varies according to gender. Regularly exercising male rats tend to lose their appetite and drop weight, whereas female rats get a bigger appetite, eat more, and maintain their weight (Staten 1991). Human studies suggest that exercise makes food more attractive to women (Pomerleau et al. 2004).