thats a great idea acctually… My Nana jan used to live in bachelors when he moved to Kuwait… tu his roommates used to eat his food… even the tiffin he used to bring to work. tu once he made Zarda (sweet rice) and added loads of rose water in it… it smelled great and all those 3-4 ppl who used to eat his food… ate it with great joy… half and hour later they were all rushing to the washrooms… uss keh baad nahi khaya.
so give it a try… ur secret recipe!!!.. 
if u are imagining things… then u will be the one taking trips to washroom… and if she really is eating then she will be the one!! and u can catch her too!!.. u can politely ask keh pait kyun kharab hai? kya howa? kuch kha liya tha! 