An intragastric device comprising: an inflation magnet provided within a capsule and configured to move towards a first end of a capsule during activation of the intragastric device by applying a magnetic field externally to a user after swallowing the intragastric device; a first chamber and a second chamber physically separated by a partition having a through hole; a separator connected to the inflation magnet and sealing the through hole before activation of the intragastric device, wherein activation of the intragastric device moves the separator to unseal the through hole to allow a chemical reaction between a first chemical stored in the first chamber and a second chemical stored in the second chamber; a balloon secured to the capsule and collapsed against the capsule before activation of the intragastric device; and an expandable volume configured to expand when the balloon is inflated by a gaseous product of the chemical reaction.