she looks diana-ish here. her wikipedia states she served as a sports trainer during her two year service with the israeli army, so it's not like she's someone without any experience of rigorous training. i have no doubt she can start eating and training for the role like every other actor/actress does.
i wont give up hope for this movie to be better than the first just yet. lynn collins would've been better, but what we have now...isn't tooooo terrible.