What is the best treatment for sloping neck/double chin? (photos)

Thank you for your question. From your pictures it does look like you would benefit from submental liposuction. Younger patients with a higher elastin content in the skin usually have a better result because the skin can is more likely tighten up around the structures in the neck to improve the definition of the jawline. I recommend that you have a consultation with a facial plastic surgeon who can go over your medical history,  do a complete evaluation of your neck with palpation of the underlying structures, and examine the quality of your skin to get an accurate assessment.

  The photographs demonstrate fatty deposits in the neck, a short platysma, and a weak chin profile which exacerbates the neck issue. Consider a chin implant to bring the projection of the chin forward  to help with facial  balance and proportions for structural support of the jawline. Liposuction in the neck will not be adequate due to the fact that there is most likely fat below the platysma muscle. A neck lift with fatty deposit removal above and below the platysma and the platysma plasty would be required. If there is excess, loose skin discovered at the time of the consultation, a lower face and neck lift is required. For many examples of both procedures, please see the video and the link below