Interesting I wonder why where you live,it wouldn't be a compliment. Atlest from where I'm from saying someone has a lumberjack's body is complimenting them because they have serious muscle definition as that type of job tends to make people that way from the job set itself without needing to hit the gym.
Really ? Maybe for boys but not for girls. Even when fitness is important here, saying to a girl she has a lumberjack body wouldn’t be taken as compliment. Translated in my language, I never hear it here.