No matter what kind of fad diet you try, or crazy new exercise routine, losing weight (or maintaining your weight) is really just about the math. Calories in versus calories out. Period. No ifs, ands, or buts.

3500 calories equals one pound, so if you overeat by 3500 you've gained one pound and if you burn an extra 3500 you've lost one pound. The great news is that the fitter you are the more calories you burn, not just by being more active but because your metabolism moves faster. So even though you probably hate math in this situation it can really work in your favor.

Although it can work against you too, if sitting around eating fast food everyday is your thing...