I couldn't do no snacks. They keep me going and from over eating at meal time.
Seconds? Well, most of the time I can say no, but not always.
Sweets? I eat 2 squares of dark chocolate almost every day. That pretty much controls any sweet cravings. I've never been much of a sweets person, though.
It's harder for me to stay away from carbs, so I try not to have any white bread products in the house, but I do eat regular pasta sometimes. Sushi is death for me; it's hard because the entire bottom floor of my university building is Japanese restaurants. Sometimes I do the udon or soba noodles, or I can find brown rice sushi, but I do give in. Then I feel awful and can go without for awhile.