Padded bras are an excellent tool for replacing volume loss for deflated breasts. A padded bra is a broad category of bras that includes, well, anything that has padding. A lightly lined bra with two millimeter thick foam throughout the cup falls into the padded bra category, as does a push-up bra that has so much padding, it adds two cup sizes. Not all padded bras are push-up bras, but all push-up bras fall under the padded bra category.
For a padded bra to be a push-up bra, the thickness of the foam will be graduated throughout the cup. The thickest part of the foam should be concentrated underneath the bust, and it will decrease in thickness, sloping to its thinnest at the top of the bra cup. Push-up bras are great for sagging breasts because the padding helps fill in any missing volume.