I've never worried about a character's weight, since I typically write a paragraph or two regarding character appearance, including body type. While I can appreciate going for accuracy, specific weight is one of those things that probably won't really help someone get an accurate guage for visualizing a character as opposed to saying "They have a thin athlete body" or "They're slightly overweight" or "This creature of a slob makes Jabba the Hutt look like a Jenny Craig spokesperson"... you get the idea.

I mean, when you play a game or watch a movie or show, you rarely are told specific measurements of a character. It's in reality a small detail. In books, honestly in a lot of them I've seen less print devoted to describing a character than a lot of character sheets on this site. A part of the fun is imagining.