1 person, 1 80-pound dog, 1 cat
Average monthly groceries expenditures, including pet food and household products: $170.55. I've been tracking this for 3 years.
I'm mostly vegetarian except for occasional fish and seafood. And pepperoni on pizza. I eat a lot of beans, lentils, split peas, and rice.
Because there's only one human we don't have to satisfy a lot of different picky food preferences, and personality-wise we're all creatures of habit who don't mind pretty much the same things week after week, so we can buy what we like in bulk and not need many new, exotic ingredients that we might end up not liking or using up.
I have a 7-month long winter CSA at a farm 5 miles from home. It costs $42 per month and supplies most of my beans, onions, potatoes, carrots, eggs, and assorted other stuff for those months. The other assorted stuff is always a mystery, so it keeps some variety in my eating.
Grocery stores are all far away from me, so I only shop at them once or twice per month.
I made a master list of every food item that I regularly buy, and every single other type of product in my house that needs replenishment ever. I update the list before and after every shopping trip, so I know what I need and never end up with unintentional duplicates.
I plan out my shopping trips, and look for coupons online after I make my list. I never look for coupons first or change the list to fit available coupons - I always make the shopping list and then see if there are any coupons that happen to fit the list.
I always check out the Land of Misfit Groceries (aka sale rack) at the back of the grocery store - but I only buy any of that stuff if it's real food that I would ordinarily buy or that can substitute for something I ordinarily buy. No buying junk food just because it's 75% off.
I check the whole receipt before I leave the parking lot. At least 50% of the time there's some expensive mistake that I get customer service to fix. This week the cashier rang in beets as avocados.
I don't believe the printed expiration dates for most things. If it smells and looks ok then it's still food. I think risks are lessened because of it being mostly vegetarian food.
I live in a tiny house. I've noticed that many people keep multiples of things like cleaning products in several places in their house, and multiple bathrooms' worth of shampoo and toilet paper. I don't have 2 bathrooms and I keep all my cleaning junk in one container and carry it around so I don't need multiples of anything.
I bake breakfast bars on the weekend and eat them all week.
I work in a profession where people want to sell us things and educate us about products, so I can count on someone bringing lunch for my whole office at least a couple times per week. Sometimes free lunch isn't worth listening to them, but sometimes it is.
I cook the rest of my lunches on the weekend, and bring them to work.
There are a lot of things I just don't need so I never buy: soda (bad for me), paper towels (bad for the world), greeting cards (can be created myself, out of things I have that would otherwise go in the recycling)... Anything that breaks one or more of those rules doesn't get on the list.