Actually, I lost a lot of muscle mass. I went from body builder to fat, took up more way aerobics too. 60+ mile bike rides in the summer. Hard to maintain muscle mass while doing that.
Not sure about brown fat.
I think of walking after dinner as being beneficial, but mainly from an insulin/blood sugar perspective.
But I think if one likes dancing, it’s a great exercise.
My daughter does it, and one thing I’ve noticed is the really great dancers have the extra body image, facial expressions, and the like, that that the other dancers do not. It takes years to get that, I think.
We went to a high school production of Footloose, and they always had one of my daughter’s friends in the front for the main, tough dance numbers. (She wasn’t one of the main parts but was in every dance number.) That’s because she’s had 10+ years of dance lessons, and has the moves while also having a smile on her face and looking the part. Meanwhile, a lot of the other kids were dying because the dance was so hard. But there were in the second or third row, so hidden by the dances with way more experience.