We spoke about euphemisms (in German: ‘beschönigende Umschreibungen’) about a month ago. Do you remember? They are those topics we don’t like talking about, because they make us feel uncomfortable. And to avoid using these rather harsh-sounding words, we choose to use more positive and polite-sounding ones.
So instead of saying that you are going to the “toilet”, you can say that you’re going to the “ladies” or to the “gents”. And instead of saying that someone is “obese” or “overweight”, you can say that s/he has a “fuller figure”.