Truthfully, it really is calories in versus calories out. Strictly speaking of food, it doesn't matter what you are eating in terms of calories. The person who eats 1400 calories a day in complete junk is going to lose weight just like the person who eats 1400 calories a day in clean food.
The difference is, the *junk* doesn't work because it makes you tired, sluggish, and it is very little food. Junk is high in fat and calories so you have to eat much less of it to maintain say, 1400 calories a day. With *clean* food (whole grains, veggies, fruit, good protein) you can feel really good and full eating 1400 calories a day (or whatever your personal intake is) ....
So that's why I think a previous poster was correct....if you stay on plan, you just naturally move towards cleaner foods because you get more bang for your buck so to speak and you feel better, fuller, healthier and more satisfied because you are getting healthier food and more of it.
Of course excersise is important too, as well as staying hydrated.
I still have a whole lot to lose, but I have always been good at losing it --- not so good at maintaining because I go back to old habits of bad eating and eating too much ...
I have always counted calories for weight loss (and worked out) with much success. It was when I lied to myself about how much I was really eating and slacked off on exercising that I would gain back (and have gained back...a lot

)
Good luck to you!