Hi Glennnn, That is a good question. Ny1969 had a thread going regarding that. It is a page or two back.
What I found out to help avoid sagging skin as much as possible is to drink lots and lots of water, exfoliate your skin, moisturize your skin especially after a shower, do not eliminate carbs from your diet, lose weight slowly (about 2 pounds a week), exercise, and take 1,000 to 1,500 mg of Lethinin a day (Lethinin has been shown to increase elasticity in the skin). One more thing I almost forgot is to use sunscreen.
Congratulations on your weight loss.