from Latin "Corpus" ? The Romans may have rubbed off on the Germans a little? http://en.wikipedia.org/wiki/Legacy_of_the_Roman_Empire
No, the dead body is "die Leiche" and the body is "der Körper". http://dictionnaire.reverso.net/allemand-anglais/leiche http://dictionnaire.reverso.net/allemand-anglais/Korper
Funny, but you might refer to a dead body as an it before you refer to a living body as it. If it were living, you'd be more likely to call them by gender. Körper is used to refer to a living body. I believe "Corpse" or "Kadaver" are used to refer to a dead one, very similarly to English. Please correct me if I am wrong, we haven't gone over that in Duolingo yet, and I just found that by doing a Google search with the knowledge that their was a difference.
"Corpse" is definitely a dead body, usually human, whereas "corpus" is used pretty much exclusively to mean a "body of work" in the academic sense. This sentence needs the dead body one, I think, although a body doesn't have to be dead to be heavy, as I know to my dieting cost. . .