My body shape, size, and clothing haven't changed since my son was born, yet I continue to gain weight. I'll bet I was 260 (6' even, and bone structure like a barrell) when he was born, and the scale is tipping at nearly 300.
I know most of it is muscle thanks to carrying my ever growing son over my shoulder, in my arms, and carrying the stroller/carrier combonations. I can tell I'm starting to get some biceps (commonly called "guns" in the testosterone world, as in, "damn dude, them some guns!") and triceps going, and whatever muscles are near the pecks and on the outside of the rib cage, but I'll admit I'm getting frustraited with the number on the scale.
Same clothes still fit, it's just that what chubbage I did have looks the same, but I'm apparently gaining some guns along with it.
So I'm stuck. With my body shape, I know I'll never look like a Brad Pitt or a Christian Bale, but I don't want to look like an overgrown, barrell chested dwarf either. Genetics has thrown me a curve ball, and I can swing, but I don't think there's a right way to hit this pitch.
I've got plenty of son carrying days left, so what I've got will at least be maintained if not increased. So in theory, if I keep doing what I'll doing, I'll keep gaining muscle weight. If I turn into a couch potatoe, then I'll gain some unapproved chubbage AND muscle because I'll still be hauling around my pride and joy.
Mass, weight, and volume all suck (and I don't mean in a vaccum either).