There are three components that can contribute to a sagging, enlarged or fat neck. Initial visualization, especially if viewing a static image such as a photograph, does not provide the doctor with enough information to determine the individual's cause of their "fat neck." The physician needs to see the patient in animation, and physically examine the neck to determine if there is a fat pad, loose / saggy skin, and / or loose strap muscles of the neck (the platysma ) that cause bands. Sometimes inheritance causes a fat pad to be prominent since a young age. The ideal patient for Kybella injections has only excess fat and no muscle bands and no turkey gobbler neck ( the skin that flaps in the wind). Kybella usually consists of a series of three injections. There can be bruising and swelling for several days after each procedure. To lessen discomfort, the physician injects a local anesthetic prior to the procedure. The Kybella, which uses bile salts chemistry to dissolve the fat, will not tighten muscle bands that are weak. Skin that has good elasticity will retract but if someone has very crepy skin with multiple folds, they may not see much pulling up of the skin once the fat dissolves. There are some risks, although rare, including nerve weakness, with Kybella and the other procedures.CoolSculpting Mini, just received FDA clearance for treatment of the same neck fat pad. It involves one hour per applicator. Some patients only need one applicator while others might need three. All three can be done in one visit, or separated based on the patient's preference for scheduling. The treatment can produce long term results for fat reduction as it has demonstrated on other body sites for the last five years that I have been performing this great treatment with a very high patient satisfaction rating. No anesthetic is needed to be injected and there is minimal downtime. No post operative garments are needed or wound care. Liposuction is a minimally invasive procedure that uses local anesthetic injections and there is the ability to immediately remove more fat in the one treatment than is treated with either Kybella or CoolSculpting. Bruising can be expected and patients often will wear a compression garment initially.In our NYC practice, I and my associate doctors examine our patients and create a plan that is best for that specific individual and the doctors, not an assistant, perform the Kybella injections or apply the applicator for CoolSculpting mini for the double chin. Patients should schedule a consultation with a board certified dermatologist or plastic surgeon for this procedure.The information provided in Dr. Shelton's answer is for educational purposes only and is not intended to constitute medical advice. The information provided should not be relied upon as a substitute for consultations with a qualified health professional who may be familiar with your individual medical needs.