A self-inflating, intragastric balloon device is activated by addition of an activating liquid into an acid or water soluble vessel located within the balloon. After an approximately pre-determined time period post-activation, the activating liquid breaches the vessel wall and causes contact between an acid in liquid form and an emissive substance within the balloon, causing it to inflate. The device is conveniently provided to medical personnel as part of a kit that further contains a syringe and the activating liquid. The device also can have acid or pepsin degradable portions that cause it to deflate after residing in the stomach for a prolonged period of time during which it imparts a feeling of satiety in the patient.