A fatty chin or fullness under the chin can be related to submental fat, jaw/chin structure, skin laxity, or a combination of these. Family tendency is common, so even with normal weight, this area can remain full. If the main issue is fat and the skin quality is good, submental liposuction is often the most direct and predictable option. It can remove the fat under the chin and improve the neck angle. Non-surgical fat reduction injections may also help in selected cases, but they usually require multiple sessions and can cause swelling; results are less predictable than liposuction. If the chin is small or set back, the neck can look fuller even when there is not much fat. In that case, chin augmentation or jawline support may be discussed, sometimes together with liposuction, to improve the profile more effectively. If there is loose skin or deeper neck muscle laxity, liposuction alone may not be enough, and a neck lift may be needed. From a single photo, it is not possible to decide which factor is dominant, so an in-person exam is important. My advice would be to consult a plastic surgeon or facial plastic surgeon and ask whether your fullness is mainly fat, chin position, or skin/neck laxity. The best treatment may be simple submental liposuction, but the plan should be based on your anatomy rather than treating it as fat only.