Intragastric device with expandable portions

An intragastric balloon configured to reside in an in vivo gastric environment for at least 30 days, comprising:

• a polymeric wall configured to have, under conditions of an in vivo gastric environment, a permeability to CO2 of more than 10 cc/m2/day, such that a rate and an amount of diffusion of CO2 from the in vivo gastric environment into a lumen of the intragastric balloon through the polymeric wall is controlled, at least in part, by a concentration of an inert gas in an initial fill gas, wherein the polymeric wall is formed of a flexible material, wherein the flexible material includes one or more non-expandable sections and one or more expandable sections, wherein the expandable sections are configured to stretch from 10% to 400% in response to an increased volume of a fluid inside the lumen of the intragastric balloon;
• and
• a valve system configured for introducing the initial fill gas into the lumen of the intragastric balloon in the in vivo gastric environment.