Anybody familiar with an elementary school-level grasp on mathematics should be able to get their head around this one. If you choose to eat lots and lots of calorie-rich foods, there's no amount of exercise that can account for it. That is, unless you're un ultra endurance athlete, but you guys are a whole other world of crazy and probably not reading this!
If you're actually trying to lose weight for real, this should be the very first thing you consider. You don't need a health professional or weight loss specialist to come to terms with this most basic of concepts. Get a calorie counter to help you. It might help you realize just how many calories are in food you thought was okay.