That's about how much money my wife and I (a preschool teacher and an actuary) spend per month for food. As long as you don't go out to eat, it's actually not that hard. We aren't great cooks, either. Just take $50 out of the bank every 7-8 days and buy the stuff you've run out of.
Also, if you have the space and can afford it, buy beef in bulk. Buy a quarter of a cow and freeze it. It'll keep for a long time. You'll need a ton of freezer space, though.
It's also never been easier to learn how to cook. There are tons of websites and YouTube videos on the subject. It makes a fun hobby as well.
Stay away from high-sodium convenience foods. While cheap, they're really bad for you!
Still schedule a couple of nights a month for eating dinner out. If you don't, you'll start being tempted to do it every night, and eventually, you'll give in, and your entire budget will be destroyed.
Thing is, they aren't all that cheap in the long run. Eventually, the bulk things like flour, spices, butter, sugar, salt combined with meats and veggies do end up being cheaper per day.
I just bought a weeks worth of chicken gizzards for less than 6 bucks. And I can trust it to slowly boil for half a day while I run errands or nap or go on shift to work. And when I'm ready, it's the perfect tenderness to fry on the skillet.
Also, two teaspoons of Cream of Wheat, makes a really belly satisfying bowl that clings to the ribs. Literally just need to boil water, put the stuff in, and stir on the lowest for 2 mins....literally quicker than boxed mac n cheese.
Angel Hair pasta is also quicker and cheaper than Mac 'n Cheese.