You let him do the food shopping
If you live with your partner, it's quite likely your fridge will be stocked with items you wouldn't normally buy from the supermarket. Sausages, pork pies, cola, last night's leftovers and, of course, beer, fill the appliance that should be mostly reserved for healthy staples that help keep you slim. Unless you possess superhuman willpower, some of those preservative-packed, fat- and calorie-laden delicacies will find their way into your body. Put your foot down and let him know that you'll be doing the shopping from now on, or - even better - give him a list and send him out to do it for you.