Firm the Flab

Recently lost 15 lbs on my own in 3 weeks and then came on here and lost 6 more. Need to lose about 20 more. I have learned I was starving my self by not eating calories i burned. It is working and I am eating a lot thanks to all for the info. So now my skin is loose. Help me firm the flab! I know I screwed up by loosing it so fast! I am doing Gilads body sculpt 3x a week for 3 weeks now ,but still flabby. Any suggestions!