FWIW, the gith are supposed to look emaciated, so Lae's build is not unusual for her race. That doesn't stop it from looking ridiculous, though. The women I could take or leave, but the men with their noodle arms are downright comical. It's hard to take Voss' threats seriously when he's so funny-looking.
It's better to imagine that Mindflayer experimentation or living on the Astral Plane made their muscles biologically more efficient and don't think too hard beyond that.
