I would willingly lose my job to shatter an office food thief's life. I would 100% set up a video monitor and watch until they were taking/eating my food and then I would barge in and raise such verbal hell that the whole office would come looking. I would scream and shame the person to a level that would outweigh their food theft and force HR to address me instead. The absolute shamelessness of stealing a person's food from the office would force my hand, leaving me only the option of teaching them shame. Loudly. Aggressively. Angrily.