If you're relatively young, some or most of the skin can snap back within a year or two. The main factors are your genetics, how far the skin was stretched, and for how long. Losing weight quickly doesn't actually cause loose skin. If that were true, then the sudden weight loss caused by giving birth would give all women loose skin. Much of the loose skin people get is actually new skin cells - a process exploited by surgeons through tissue expansion: www.plasticsurgery.org/Reconstructive-Proc
Unfortunately new skin cells don't go away without surgery. But give it 2 years before deciding on surgery, to see if the appearance improves with time.
You might be able to fill in some of the looseness on your arms and legs with muscle, though strength training. Around the abs, not so much, since the abdominal muscles are thin and aren't capable of much growth. Regardless, it's still good to do a full-body strength training routine.
Oh, and congrats on your weight loss!
Edited by: CHERIMOOSE at: 2/7/2013 (15:32)