Weight loss before or after chin liposuction?

It is always best to be at or near your ideal weight before undergoing liposuction under the chin, so I would recommend losing the 20-30 lbs. before your procedure.  

It is recommended to be at an ideal, stable weight when getting liposuction. I find that VASER liposuction in combination with ThermiRF are best for contouring the chin, if you're a candidate. See an expert for a formal evaluation. Best, Dr. Emer

Thanks for sharing.  You should be at a stable weight.  20-30 lbs can be significant if there is alot of weight in you neck.  One option is you could lose half of it too and have the procedure and if you lose the other half it likely won't be a big deal.  Ultimately you will need to be seen in person for the surgeon to best guide you. 

  Liposuction under the chin is best performed for diet resistant fat present in the neck.  Its best to lose the weight first, and then undergo liposuction.  For more information and many before and after examples of neck liposuction, please see the link and the video below

 Hi, I have performed many Neck Liposuction procedures and Chin Augmentations using chin implants for over 30 years.  Non smiling photos of your face from the front and side would help in the evaluation.  If your face and neck has a large amount of excess fat, loosing the weight before the procedure makes sense.  If the chin is also weak, this will create an imbalance making the nose appear larger, the mid face top heavy and the lower face look short that de-emphasizes the lips and allows early formation of a double chin.  Chin augmentation using a chin implant will add projection to the chin creating harmony and balance to the lower face While liposuction can reduce excess fat below the chin and across the neck, it alone can't increase chin projection that a chin implant will provide (when the chin is weak) allowing the lower face to be balanced and in harmony . 
 I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess skin removal) to be very safe, quick, highly effective and far less invasive than a sliding genioplasty.  I perform chin implant surgery in 30 minutes or less, often using a local anesthetic alone.  
Hope this helps.