So then what exactly are we debating about here? lol
You said muscle doesn't weigh more than fat, but it's denser than fat. That's like saying "pie doesn't taste better than cake, it's just more delicious than cake."
if you want to gain weight, all you need to do is intake more calories than you burn off. i'd say eat an extra 500 calories a day (if can be healthy foods if you want) na dhtat will put on weight in a healthy time span ( 1 - 2 pounds a week). all my sports med and nutrition classes go over this and say the same thing.
When my time comes, I want to be burried face down. That way, anyone that doesn't like me, can kiss my ass!