Gamerofthegame said: She'd be a few pounds heavier, wouldn't she? Being wet and all. And the towel, too, which is also wet.
Looks to me like she just got out of the sauna, so that's all water that came out of her body mass. Keeping the soaked towel on kinda defeats the purpose of the whole stripping-to-fool-the-scale thing, though.
Maybe she's trying to drop some fat so that Yuyuko thinks she's less appetizing?