You can use a icon just to rappresent fat (like this one https://www.flaticon.com/premium-icon/fat_1951542) and put it next to a person like a emblem in a similar way to this:

https://www.iconfinder.com/icons/2740474/personal_protection...

hope i did convey the idea.

edit: You should probably use a icon like this one https://www.iconfinder.com/icons/830113/character_figure_man... for the person instead the one i linked, since showing only the head instead of the entire body is not very clear (i used that one only for explain the emblem idea)