I make the budget for my husband, step son and me for groceries. We limit ourselves to $500/month. Most months, I don't go over $400. A month or two a year, I may go over. It usually balances out.
I used to spend around $750/month on food. Thats way too much and we were wasting food. I started couponing (I know this isn't for everyone) and I really watch the sales. I also live really close to a produce outlet and bread outlet, so I am able to get my fruit and veggies for about half the price. I get all my meat in bulk and I divide it up (and date the package...I don't let meat go beyond 3 months in my freezer). I always make extra for leftovers. This helps save against eating out. I buy snacks so I always have something on hand in case I get hungry on the road - this usually ties me over until I get home. If we eat out, we limit it to once a month, and we usually ensure that if we do, we get a discount on groupon (or other website like it). We hardly eat fast food....that stuff is so unhealthy for you. I make all my food from scratch (I work full time - 5x 12 hr shifts a week....)
If I am at the end of the month and I have reached my budget, I look through my cupboards to see what I have, and if I think I could make something out of it, I go to a website that has a recipe finder based on the ingredients that I have. 9 times out of 10, I can find something that is tasty and works, and is quick to make. This has helped me immensely! Also, you can cook anything in a slow cooker. I use mine about twice a week! I'll throw it all in before I go to bed, and my husband turns it off in the morning. We then both have something for a lunch.
We may be frugal, but we have really learned to utilize our money for other areas in our life. We are basically debt free, and we have the luxury of travelling now 3-4 times a year. When we do travel, we also try to eat in as much as we can - this saves us money for other things on our trip!