Building muscle after huge weight loss

Hi I have lost 23 Kilos over a six month period and now notice my skin is loose and sags .......I not sure where to start to regain muscle which i feel sure Ive lost after rapid weight lose.
Annik

How did you lose the weight and what are you doing to maintain where you are currently? Is/was there an excercise program in place during the weight loss? What is your current weight?

The skin might not shrink, depending upon your age. If it does not, you might have to consider surgery.