Overeating makes you fat like OTIS states.
Count your calories and if you are actually serious visit
http://forum.bodybuilding.com/forumdisplay.php?f=16 and read up on some stickies.
I have been cutting down body fat through diet and wieght lifting. Truthfully cardio is not even needed. It's good to have to make your cardiovascular health better but fat loss can easily be achieved through diet alone.
Diet pills are all fake and gay. Seriously! Any studies that have been conducted always are "pills combined with diet and excercise". What do you think is creating the fat loss? Not the pills. Also a high number of studies are not even done on humans, they use rats, the rats don't die and then magically the pill apear on shelves.
Also all these sugary shit foods you mention are addictive. I removed refined sugars completely and only take in real food sugars. Sugars from cakes, sodas, candy bars will fuck with your cravings and make you over eat. Changing your diet around will be hard at the beginning but becomes second nature. I highly suggest you check out that link, it has way more info then you will find asking questions on here.