The only thing that changes loose skin substantially is not having loose skin in the first place, and it all depends on genetics, body shape and where the weight was stored and skin stretched.
I have "shrinkles" in that same area and my abs, my arms aren't bad. Some areas that have just a bit of loose skin, might look a bit better with some underlying muscle growth, but the fat that was there was between your muscle and skin, even if you build muscle, it doesn't really occupy the space where the fat was, there is still a layer of fat and a bunch of loose skin.
I hate the shrinkles on my butt, and I don't care for them on my abs, but I don't think I'll be doing anything about them, unless they get irritated frequently or something, but so far they have not.
That being said, I think it's a good idea for anyone getting the surgery to start a skin savings account as soon as they decide to get the surgery. Put some money in there every month for two or three years until you reach your goal and maintain for a while, and then you've got some money to cover a bit of work if insurance doesn't. If you get to that point and you decide you aren't going to get the surgery...buy yourself a new car or something.
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