The fad diets, like you say, will lose you weight, but generally you go back to the old habits and diet and surprisingly put the weight back on (often more). Realistically you have to make a permanent change.
Its often said that all you need to do is burn more calories than you put in, and that is true but doesn't deal with habits or lifestyles. Also there are the empty calories where you eat them and don't feel any real benefit (i.e full, proteins, etc). And there is an old saying 'you can't outrun a bad diet', exercise is obviously good for you but realistically weight loss is about 80%+ about the diet.
The above is very good advice. Its about what you take in not what you burn