Your Diet should consist of low carbs, low fats and somewhat low calorie
Here is my favorite
Stir Fry- This dish is easy to make and is loaded with nutrients and is my personal favorite not only as a side for a meal but it can also be a snack.
Broccoli, Carrots, Cauliflower, Bean Sprouts, Apsaragus, Corn, Green Beans. Steamed in a pot for about 5 minutes. It sounds like it would be nasty but once you add stir fry sauce it's actually pretty good.
Sadly if you've always been overweight, it's going to be hard to get slim because for the most part you'll just be fighting genetics, which, by the way, isn't easy at all.
But one thing I always tell guys that are looking to lose weight is to pick up a grappling class (submission wrestling, BJJ) a person around 200 pounds burns a little over 500 calories in a 1 hour session