Rest v. Exercise & Skin Elasticity

I like doing my pilates; however, after seeing yet again the focus on rest my question is: How does your skin elasticity hold up during a water fast?

Will the body keep up so that you don't have excess skin?

Have better results been seen with light exercise or with rest only?

This question predominately applies to those that have had a sizable amount to loose and dropped 20+ pounds on a fast.