Why do raw vegetables weigh more than cooked vegetables?

Raw vegetables don’t necessarily weigh more than cooked vegetables—it depends on the type of vegetable and the type of cooking method. Typically, if you roast or sauté vegetables you will cook off some of the water, and the cooked vegetable will weigh less than the raw. But if you boil or steam your vegetable, it’s possible the cooked vegetable will weigh more than the raw.