Fat cells are set for life at around 8 years old. That doesnt mean that all your fat cells are active because if it was the case, you would be extremely obese. When they do lipo, they also remove the cells that created fat ( active) but the other ones that were not active are still here. This means that if you get more overweight then you were before, those cells will get activated and you will gain fat. If however you stay at same weight ( bodyfat %) or lose weight, those cells wont get activated so you wont be gaining fat. The fat that got moved to new area ( butt and hip) will react to gaining/losing weight however. Hope you get what i mean this time.
the links i provided are description of the tool used. As you can see on the VASER website, dr berbari is certified for this technology.

What i said about REVOLVE is comming directly from the consultation i had with dr Berbari. She claim having a real 80% of fat cells surviving using this filter. I asked her the question.
No,i never had surgery to hips but i started my transition a little to late ( in 20's) so i didnt get the hip bone growth part. Still i was lucky, i have 40 inch hips as starting point with a 29 inch waist. There are a lot of womans that also have hip dips, i think ive read somewhere that its 50% of womans. It is just not beauty standard. They are also named Violon Hips , you can get more info on google. Im doing this surgery to fix the hip dips and of course get more width and curves .
I will point something about HRT and "fat redistribution" . The fat isnt really moving area, its just that fat cells react differently ( getting active or inactive) with hormones. Still, if you have a lack of fat cells in a zone, HRT wont create new fat cells , it only activate or desactivate according to the hormone regimen you are in. If you have a lack of fat cells in a zone, hrt will activate most of it according to feminine fat distribution but it wont be creating new ones so you may not have the "curves" you desire. This is why lipo with fat transfer is a good solution
There is one girl from here that shared experience 1 year and half ago
https://www.susans.org/forums/index.php/topic,180220.0.html