The closer to fresh your food is, the better it is for you, so try to
do most of
your shopping around the outside of
the store, since the closer you get to
the middle, the more processed the foods become. If you can't get fresh, then opt for frozen foods whenever possible.
All that said, don't forget that there are also medical issues which may cause belly fat, so make sure you check with your doctor to rule out issues such as insulin resistance, etc.