A gastric balloon apparatus. An apparatus is disclosed that is insertable into a patent's stomach for treatment of overweight. The balloon occupies a volume of the gastric lumen to provide a sensation of fullness after the consumption of only modest amounts of food. The balloon apparatus has a basic toroidal shape to prevent blockage of the entrance or exit lumens of the stomach and promote proper passage of food through the stomach, while protecting the stomach lining from ulceration and irritation. A series of toroidal balloons of graduated diameter may be joined by inner and outer sleeves to define a funnel-shaped apparatus which expands when food is ingested, thus satiating the patient with substantially reduced quantity of food. A balloon storage and insertion apparatus also is disclosed, whereby a gastric balloon according to the disclosure may be pre-inflated and stored ion a tube for later use, whereupon the pre-inflated balloon is deployed into the stomach. Various mechanisms are disclosed for providing a pre-determined deflation of an inserted balloon, permitting the deflated balloon to be excreted from the body.