Weight loss question......?

Alright I started working at walmart back in july of last summer pushing shopping carts for about 7 hours a day 5 days a week. My weight when I first started was 230lbs (overweight) and I am 6ft tall. now im about 180 pounds (slim) after 9long treacherous months. Having this job was perhaps the greatest thing that could ever happen to me but now I built up quite a bit of muscle this winter (from pushing carts through 6inches of snow)and now its making me look bulky because I still have a layer of fat over my ab and chest region. My question is what foods will help me lose the fat but still keep my muscle tone I have. And will the summer heat put stress on my body enough to accelerate weight loss since im kind of in a plateua and use to pushing carts in cold weather? P.S. And before anybody says get a real job and that im a loser for working here. Im 19 and im going to baker college and this is a good job for now both health wise and money wise. And sorry about the autobiography just wanted to give some background to my weight loss.