I seem to be the odd one out - if I have cash in my wallet, I'll spend it without thinking. I'm better off using plastic. It defies logic.
1: What is your food waste? What are you throwing out? Do you make big meals and don't finish them? Are you buying produce and not using it before it goes bad? Figure this out and adjust accordingly (make smaller meals, either force yourself to eat those veggies or just don't buy them, etc.).
2: Keep track of everything you buy and at what price (most importantly, price per unit). When I was trying to get my food budget under control, I kept track of everything on an excel spread sheet. I bought 1lb of chicken for this. I bought two boxes of triscuits for that. First, it helped me figure out when I was actually getting a good deal on something (versus the store telling me it's a great deal). Second, when I was typing out everything I bought, it made me stop and think - did I really need that? I don't do this anymore, but it helped me set up good habits.
3: Stock up during sales. This might screw your budget up for a short while (I bought a ton of meat on sale in September, so my budget was whack, but I've hardly had to buy meat since). Pantry goods are another that I stock up on during sales.
4: What about your dietary needs is making you spend more? (Not a question you need to answer here, but be aware of it.) With better preplanning, is the cost something you can control?
5: Meal plan. There are a lot of great apps out there, but I just use Google Calendar (I use it for my day to day stuff anyway). I have a second calendar called "Meals" that overlaps with my regular calendar. If I'm good (and I'm not always), I'll try to figure out Saturday what I'm doing for the next week, or at the very least Monday/Tuesday, which are my busy days.