How to stop my roommate from stealing my food?

I’m going crazy here and need some advice. <br><br>My roommates has been taking food from the fridge that isn’t his. He’ll take my yogurt and drink it and then put it back in my fridge. I’ve told him before not to take my things but he just shrugs it off and keeps doing it. <br><br>I’m starting to feel like I’m living with a thief. I’ve stopped keeping perishable food in the fridge because I don’t want it to go to waste. I’m tired of being treated this way and I don’t know how to stop him.<br><br>Has anyone else dealt with a roommate stealing their food? If so, how did you handle it?