As DMC said, your muscles need time to recover - that's where the growth comes from. You can actually hurt yourself doing it your way.

You really shouldn't go to the gym every day, but if you do, it'd be better to follow something like this:

Day 1 - Lower body workout / stretching
Day 2 - Upper body workout / stretching
Day 3 - Treadmill (or other aerobics) (60 min)
Day 4 - OFF, or: Swimming / sauna / hot tub, etc
Day 5 - Lower body workout / stretching
Day 6 - Upper body workout / stretching
Day 7 - Treadmill (or other aerobics) (60 min)

If you have the time, do the treadmill every workout day for 30 mins afterwards. (I think you're suppose to do the aerobics after lifting if I remember correctly...?)

And I think you're suppose to do your real stretching after the workout, but must warm-up before.

As I said, it's been a while for me, but listen to DMC - and if you don't trust people on this board, then go to a board devoted to fitness. Or google some fitness sites. :p

You'll eat more if you're working out - your body needs it. That's normal, healthy, and not a problem.