I don't know if anyone has mentioned this, but a huge one is portion control. And not in the sense that you should eat half what you did before, but in the sense that it really IS better for your body to process smaller amounts of food more often during the day that three ginormous (yes, that is a word, dammit!) meals like most people eat. I am probably not the best example because I don't eat breakfast (hate all breakfast foods in general and also I usually get really nauseated if I eat too early), but I eat a little something every 2 or so hours. It's never anything huge, usually just a granola bar or some carrots. I do eat 2 larger meals each day, but it's usually something like low-sodium soups (or ramen, because let's face it, I'm a poor student), or some kind of meat and veg. My stomach is probably shrunk pretty small because even if I try to stuff myself, it's impossible to eat the amount I used to eat in one sitting. I think it was Dar who told me if you keep giving your body little bits of food, your metabolism speeds up because it expects the next dose and burns the last faster in preparation for the next if that makes any sense?
I was also told that a great way to improve your diet is to shop only from the outsides of the store. This means, you buy from all the fresh areas (dairy, meats, fish, bakery, produce), and you're not buying canned stuff with preservatives, etc etc. Not sure how much of a help that'd be towards losing weight but it's probably much better for you in general.
And don't eat when you're bored! Take up knitting or something! Boring-eating is really evil!
