1. You are overestimating how much calories you burn- everyone always assumes they are burning tons of calories every time they grab a weight or step on a treadmill. Your average person does low intensity cardio which burns about 6 calories a minute or 1080 calories if you do about 45 minutes of cardio 4x a week. 1080 calories is equal to a fast food burger, fries and medium drink. This means that one cheat meal will make your cardio for the whole week insignificant. You must do high intensity cardio and resistance training to burn the most possible calories.
2. Your underestimating how much you eat-classic fault is that many people think they don't eat as bad as they do. If you were eating good you wouldn't have an issue with losing fat. The best thing to do is to keep track of your daily eating with http://www.fitday.com/ a site that lets you do this for free. Remember to be honest with yourself!
3. You starve yourself- So its simple right just don't eat and the fat will melt away, right? WRONG! Starving yourself will slow your metabolism and burn away muscle stripping you of your best two fat
4. You think you eat " healthy"- Things in the store are not what they appear to be. Just because it says low fat doesn't mean it is healthy. Usually brands will decrease the fat and increase the salt or sugar. Pay attention to all the ingredients and don't just buy into the labels on the front. Eating whole foods that are unprocessed is your best bet.
5. Your inconsistent with everything- working out really hard for two days is great but if you follow that will a week off then you will go nowhere. Having 3 days of eating very healthy lunches but then having pizza for dinner on each of those nights does you no good. Your workouts and your diet need to be consistent. If you do not maintain consistency you will never make strides in losing fat and reaching your goals.