An undergarment is provided for discretely altering the outward appearance of a person who has scoliosis or other physical deformity, in order to mask or obscure the deformity. The undergarment includes a main garment, a plurality of garment attachment elements spaced along inside surfaces of the main garment, a shoulder insert, and a torso insert. The shoulder insert has its own attachment element for releasable engagement with at least one of the garment attachment elements located in a shoulder portion of the main garment, and likewise the torso insert has its own attachment elements for releasable engagement with garment attachment elements located in a torso region of the main garment. The torso insert is configured to simultaneously extend along at least one of the garment's side portions (i.e., along a wearer's side) and the front and/or back portion of the garment.