I was first going to suggest a budget, but it sounds like you’ve tried that and he hasn’t stuck to it.

When you say one of his weekly expenses is food, does he eat out a lot? The cost of eating out (restaurants, fast food, etc.) adds up quickly without realizing it. And while food is a necessity and something he may not consider as wasting money, it’s still more expensive than if he were to eat food at home and cook a meal. If you know this is the case, it could just be a habitual thing, and him needing to get into the habit of eating out less.  if you cook meals together/go grocery shopping together, he may be less inclined to eat out, and instead eat or snack at home.