I'll add to your first point and say if she doesn't pay up, take it out of what you owe for rent.  Also, if you're splitting the bill for groceries, then you're definitely paying more for what she eats than she does for what you eat. If this is the case, then start paying for your own food and store it in its own separate area in the kitchen, and make sure she knows not to eat it without asking yo  1006  u first. If she eats your stuff without your permission, ask for compensation. If she doesn't pay, lock the non perishables in your room and get a mini fridge for the rest.  If you're not splitting groceries, then just make her buy ingredients next time and pay her your half later, after seeing the itemized receipt.