Heh, what a novel idea -- wanting to GAIN weight. Bulk up. Muscle up. Yeah, I v a g u e l y remember that sort of motivation, but it was a loooonnnnnnnng time ago.
I was remarking to a friend who just turned 80 that I thought eventually older people would start losing weight and could start swilling milk shakes and stuff to not lose too much.
He said his weight kept increasing until around 78 when suddenly he started losing 10 pounds here and there at a time. He said he now weighs what he did as a teenager.
So enjoy the raging metabolism while you can, superpug1. And of course you realize you're lucky because some poor souls have serious weight problems their entire life.
When you start seeing signs of gaining more weight than you want, don't delay in adjusting your life style. It's easier to fight a few pounds than a lot.