Food really does take a huge chunk of people's income, but there is a cheap way to get it and a not-so-cheap way. How to do it cheap?
First of all, always cook at home. I can feed a family of seven for about $75 a week at home. Eating out--even the cheapest way I can find--costs at least a third of that for just one meal, which often doesn't leave anyone feeling full and usually isn't terribly nutritious. Not only cook at home, but make things from scratch whenever you can--hamburger helper costs more and feeds fewer than buying noodles, sauce, spices--you have to buy the hamburger either way!
Secondly, don't bother to clip coupons unless you MUST have the name-brand product. Then coupons can save you a bundle. But you can get the same products significantly cheaper if you wait for the store brand to go on sale and buy it instead. Most of the time, the store brand is just as good as (or better than) the name-brand product. Even when it's not, if you're shopping for small children like I am, they don't care.
So, instead of clipping coupons, watch the weekly ads. If they don't come to your mailbox each week, watch them online. Then, when products you use come on sale, stock up. I still spend about $75/week stocking up (like when I buy 50 lbs of hamburger in a week because it is $.99/lb), but I don't buy a single weeks' worth of groceries--I buy a bunch of what's on sale and then make good use of the cupboards and chest freezer. Doing this, I can make dinner for all 7 of us for $5. For everything.
Third, if you can muster the ability and space, plant a garden. A packet of pea seeds costs less than a dollar. You can't buy a pound of peas for that. Grow your own. We can't do this in Vegas easily, and I can't garden when I'm pregnant very well, but it really is a good idea to pay in work instead of in cash when you can. When you do plant a garden, we've found that it's wise to save some seed for next year so that you don't have to buy seeds each year. For example, we made jack-o-lanterns one year and saved a handful of seeds. I let them dry and then stored them in a ziploc bag. Come spring, we planted them and had TONS of pumpkin plants. We moved before we got to harvest the pumpkins, but the lesson was well learned--from one $2 pumpkin we got one halloween, we would have had enough pumpkins for each kid to have a jack-o-lantern the next year. For free.
By growing your own, if you can stand the work, you can have a winter's worth of canned or frozen fruit or veggies for pennies.