Does losing 100lbs or more make your skin sag and look nasty?

Hey my name is sienna :-) my best friend is gaining Lots of weight. She was never skinny she always had a lil extra but she looked good for example Jennifer Hudson like that. She has put on a lot of weight. She is 5-4 and weighs a lot. She went from a size 16 to 26. I always try to get her to walk with me but she gets tired quick. She is supposed to be getting the lap band surgery in three months and is worried her skin will sag and look nasty. I told her it wouldn't because she is young 21 and should do body sculpting exercises. My mom lost a lot of weight and said skim milk and fish oil softgels help.