Excess calories don't come only from food, but they also come from liquids we drink.
The only liquid that doesn't supply you with those extra calories, is water! It actually does the opposite, it can fill you up & prevent you from overeating! So try to drink at least a liter of water a day.
Try to avoid the following drinks because they either give you extra calories, or increase the hunger sensation, thus driving you to eat more!
The worst sort of drinks are the sugary drinks like sodas & punches, which by the way have no nutritional value! Stay Away from these!

The drinks that come in the second place are those labeled "no-cal" & then natural fruit juices, limit yourself to one glass of these a day ... Not More!
Low-fat milk comes in third place, it has a bit of fat, but gives lots of nutrients.
In fourth place are non-sweetened tea & coffee.