Flabby Belly After Teen Weight Loss - How to Tighten Up?

Thank you for the question and pictures. Congratulations on your weight loss!

I think you would likely benefit from the tummy tuck procedure. A word of caution may be in order... In my opinion, For patients with your history,  liposuction or mini tummy tuck surgery are  operations that  produce very limited results and are very rarely indicated.  The mini  tummy tuck procedure involves a shorter incision but does not address the majority of the abdominal wall issues present for most patients who present consultation. For example, the area of skin excised is quite small. The abdominal wall musculature is addressed below the umbilicus leaving the upper number wall potentially lax. The appearance of the umbilicus is not necessarily addressed sufficiently.

For most patients who have had pregnancies and/or weight loss a full abdominoplasty is necessary to achieve the desired results. Of course, there are downsides (including a longer scar and probably a longer recovery time) but for most patients the benefits outweigh the downsides. It is not unusual to see patients who've had mini tummy tuck  surgery present for  revisionary surgery.
It is important to work with a well experienced board-certified plastic surgeon to obtain advice (based on good ethics and judgment) to  improve your chances of a successful outcome and minimize the need for further surgery.

I hope this helps.

Consider removal of skin to tighten area. If you have lower belly looseness then you could get a mini-tummy tuck where just the lower section fascia is tightened. If fascia is not loose then lipo. good luck!

Congratulations on your weight loss!  Loose skin after significant weight loss is very common. Some people claim that intense (cardio) exercise can tighten loose skin. You didn't mention if you exercise, so it certainly wouldn't hurt to try exercising for a few months and see if that helps.  

If exercise doesn't help, then I suggest visiting with a board certified plastic surgeon to discuss your situation in more detail.  A tummy tuck (abdominoplasty) is the procedure commonly performed to tighten the front of your abdomen.  I hope that helps and wish you all the best!