What's my body doing?!

lq022

I'm noticing that after high-impact exercises (for me: kickboxing, boxing conditioning, jogging on treadmill to a good sweat) that afterwards, I'm not very hungry... which is a good thing . but since I know I need the protein especially after the aerobics classes, I'll have a portion of protein and some veggies ... but once I start eating, then I become more hungry. Is this my bodys way of replenishing the calories, so I should give into the hunger ... or could it just be a psychological response?? Also, how does my metabolism play into all of this?