How Does Weight Loss and Gain Affect the Look of a Chin Implant?

Weight changes shouldn't appreciably change the appearance of the implant itself. Weight loss can affect the tissues of the neck under the chin, though, and this may be what you're noticing. Directed fat grafting may help the sunken appearance you're concerned about, but this is hard to assess without seeing you.

Weight gain or loss should not affect the chin implant, however, it is the relative change of facial soft tissues that have caused the chin implant to appear less prominant with weight gain and less so with weight loss.