I think cocoa butter might help. I used it when I started working out to prevent stretch marks cause my muscles were growing too fast. usually most products with cocoa butter or shea butter have vitamin E oil. I know they are supposed to help with stretch marks, but I think they might help with loose skin. But a lot of people think that all those cream treatments are a waste of money and don't work. It is a personal preference, I doubt that they actually help because I still got a few stretch marks.
If it is really bad you might want to get it surgically removed. Go see your general practicioner, then get refered to a plastic surgeon.
The older you are the harder it is to have the skin snap back on its own. It should though, look at pregnant women, their skin snaps back pretty easily.
Slow weight loss is also a way to help.
This is just some stuff I read. I wish you the best of luck and the tightest of skins.