Described herein are various embodiments of differential air pressure systems and components for differential air pressure systems. The air pressure systems comprise a chamber for receiving at least a portion of a user's body. Pressure in the chamber can be changed to adjust force on the user's body. Described herein are various methods and related structures for sealing a user into a pressurizable chamber. Also described herein are various methods and related structures for changing the shape and/or height of the chamber. Described herein are various types and configurations of chambers and support structures for chambers. Also described herein are various methods and related systems for treating various conditions using the differential air pressure systems, including but not limited to obesity, cardiac disease, multiple sclerosis, cerebral palsy, or Down Syndrome.