A recent discussion on Facebook brought up several details in common between the childhoods of overweight people that bear mentioning to those trying to raise healthy kids.
Make time for dinner
Dinner time should be a family social occasion with food present, and let natural hunger dictate how much food is eaten during that time. If the child can be excused to go play by wolfing down a measured portion, you're rewarding them ignoring hunger signals and cravings and forcing themselves to eat. Schedule at least 20 minutes for dinner. If your child doesn't have the patience to sit as long as the adults, set a time at which they will be excused, not a consumption requirement.
Don't clean your plate
If you have to, get a pet chicken or pig so the food isn't "wasted". It is reasonable to ask a child to try a new food, but making them eat all of it isn't going to make them like it, and will teach them to try to eat without tasting. It may be reasonable to reserve their plate in the fridge until they claim hunger two hours later. Don't sweat unfinished food, a hungry child would have eaten it by now.
Don't leave out large volumes of food
When leaving out snacks for the kids when they get home from school, leave out measured portions, not large supplies. If the kids have already developed mindless eating habits, it's very easy for them to just munch and munch in front of the TV or game console until you get home. Consider if snacks are even necessary, talk to your child about how they feel after school, and if they are tired, they might try a nap rather than sugar/starch to regain energy.
Remember childhood pounds never go away
Fat cells can shrink, but never go away. They're sitting there waiting to re-expand and fight fat loss for the rest of your life. We don't want to be overly obsessed with thinness in growing children, they do need some fat for brain development and calories on board to support those growth spurts, but a trend of putting on excess pounds is not likely to stop without intentional intervention, changing habits and diet. It may be easier to put on pasta every night when the child is old enough to start prepping dinner before you get home from work, but if that doesn't agree with your child's metabolism you may need to find other alternatives or upgrade your child's cooking skills.