The injection of steroids into the skin is a significant event at the cellular level. After such an injection, your skin will be probably changed. The skin will be thinner and will have more difficulty healing. When a steroid is injected into a fat grafted area, the fat will shrink and contract. This may be the effect that he wants if steroid is injected into an area that may have a little too much volume.
Local steroid injections are used to address small pockets of fat .This fat will melt down and this should be done with care to avoid melting of the superficial fat which will result in skin discoloration.In general steroids will not make fat regenerate but over time the same area could have the accumulation of fat from remaining cells.