A food steamer or steam cooker is a kitchen appliance used to prepare various foods in a sealed vessel that limits the escape of air or liquids below a preset pressure.
Most steam cookers also feature a juice catchment, which allows all nutrients (otherwise lost as steam) to also really be consumed. When other cooking techniques are used (eg frying with butter or oil), these nutrients are also generally lost as most is discarded after baking.
Due to their health aspect (cooking without any oil), food steamers are used extensively in health-diets as Cuisine minceur, the rawfood diet, Okinawa diet, macrobiotic-diet and the CRON-diet.
Food steamers release less heat to the kitchen environment, therefore helping keep the kitchen cool during hot summers.