Lot's of people here seem to want to lose weight. Well, I've been there and done that. About five years ago, I lost 30 pounds and never put it back on. Exercise was part of it, but the secret was mainly diet. A very simple diet.
I would eat my regular meals. A good breakfast (very important), lunch (my main meal of the day), and a small dinner (sandwich, bowl of soup, etc). No change in diet there. The only thing I did was eliminate snacks altogether. Whenever I felt like I had to eat a snack (I used to eat lots of donuts, chocolate, and other sweets) I would eat a dill pickle. After a while I hated pickles. I think it was "negative reinforcement" which is a fancy term for punishment. BTW: Pickes have almost no calories. Once I had lost my weight, I never went back to snacking the way I did before.
That's it. That simple. No fancy systems, no costly guides.