This was a QUORA questions I answered.
I’m going to keep it simple. Consistency! Particularly with strength training. Follow a program regiment while increasing your weights each session, but not by a lot or you will more than likely injure yourself. Leave your ego outside! Smaller increments with perfect forms adds up in the long run to great strength gains. In my stronger days, what worked for me was to do two weeks of power lifting type training, followed by a third week of just shaping movements. Follow this program 12–20 weeks along with proper diet, sleep, mindset, supplementation, and you will get strength results which means muscle building! You have to get stronger to get bigger muscles! Best of luck!
It is important to be well hydrated as dehydration seems to contribute to thst loose skin look if you have it. The younger you are the better too. Older skin doesn’t seem to bounce back as well. When you are consistent with weight loss and keeping it off, the skin does eventually adhere to muscles if there isn’t too much loose skin. If you have lost lots of weight or just have a lot off loose skin, then fixing loose skin must be done with surgery. Hope this helps!