I can say what worked for me, which I found particularly easy after a short time:
- Cut out all caloric drinks other than stuff like milk, tomato juice, V8, booze. (Basically, sodas and fruit juices)
- Stop buying snack foods entirely.
- Don't buy pre-prepared foods like frozen meals, even frozen veggies with sauce (they usually load it with calories). Cook your meals and use "raw ingredients" as others have mentioned.
- Stop eating dessert.
Within a month, I didn't miss a thing. Now, I actively despise the taste of all that. (My wife will often order a desert when we're out and ask me to try some. Tastes overpoweringly sweet these days. Yuck). If it sounds like too much at once, start with one of the things. And add more as time goes on.
I never paid attention to portions. Just stuck with meals I cooked for myself (start easy, with whole chickens, roasts, etc, if you don't currently cook).
Combining with exercise won't hurt, even if it is just going on walks (multiple miles).
Basically, you'll end up eating more whole fruit, veggies, meat, and less carbs - especially the worst kind (sugar or 'fructose corn syrup', which is also sugar). May take longer to see results than a diet, but results will be permanent so long as you don't cheat.
