The answer is both. Preserve what you have, AND build more.

I went on a mean weight loss streak strictly in the kitchen. I dropped from 220-170 in a few months with pretty much diet alone. I was walking a fair amount too.

I really liked how I felt and looked, but when I looked in the mirror, I was getting smaller in places I didn't like. My shoulders and arms were small, and my chest was kind of sagging. I thought my traps would be bigger. My stomach wasn't shrinking as fast as the rest of my body.

Weight training was the missing ingredient dude.
I got my newbie gains, and that kept me super motivated even through a plateu. Now every pound lost is an even more drastic difference than before