One of our greatest problems with dieting is that calories are not really equal and the effect food has on you really depends a lot on your particular metabolism. Maybe if you eat more than 2000 daily calories worth of stake and diary you get fat, but I can eat more than that without any effects whatsoever, while a single cookie ads 2 pounds on me (my body retains a lot of water after eating sugar).
And it's a problem because the common advice given to people doesn't work so well. Which is why dieting hasn't really caught on.
Personally I separate foods in dangerous (for me) and non-dangerous. I measure my weight every morning and I know precisely what types of food lead me to gain weight. For the non-dangerous kind I have no restrictions and eat as much as I please, as long as I don't combine it with the dangerous kind ... whenever I do that, I starve myself a little (for a day or so, eating some fruit and a yogurt), then it's back to normal.
Btw, I lost 44 pounds this year after cutting my sugar intake drastically + a dissociated diet that lasted for 4 months. Right now I'm happy that the diet is over and my weight has stabilized to the point that I eat whatever I like, except snacks (which I never liked anyway) and sugars. Of course I don't overeat, because I don't feel the need to do that anymore - somehow giving up on sugar has cut into my appetite.