Veteran Sergeant wrote:Then why even participate in a theoretical discussion of Space Marine weight?
Nevermind how dumb it is to suggest that science "never" has been a factor. I'm fairly sure that
most things that we understand (though I guess you might not realize are "science") still apply in
40K, even if there are elements that don't. I mean, gravity seems to function more or less the same way. That's "science". People still seem to eat food, and die when you cut their heads off. That's "science".
It's a good thing I'm rarely surprised by the sort of incomprehensible things people post here. I'd probably develop neck pain from shaking my head or sores from palming my face constantly.

That you took my post deadly seriously and responded in a condescending manner (Such as suggesting that I am truly so stupid as to believe gravity wasn't science) only suggests that you feel the need to attempt to come off as more intelligent than other people and feel superior, a trait that is rather easy to spot in your posts. Is there any particular reason you are like that?
Since you wish being both anal and petty (As well as unwilling to deduce the meaning of what I said, which shouldn't be particularly difficult), I will rephrase: What looks or sounds cool takes precedence over what would be logical or scientific in Warhammer 40,000. It's why tank designs are based off of rather outdated WWI designs, for example.
Do note that I never meant to imply that you couldn't
try to deduce based off of logic/science for an answer in
40k, only noting that I don't believe that the writers of the fluff consider it to any great extent.
Seven hundred pounds doesn't sound particularly off to me, but no, I don't have a background in "theoretical biology". Keep in mind though that they have a few extra organs or components in their body, like the Black Carapace for example, and they are overall much denser than a human being, their bones, musculature, and skin being quite a bit tougher.