Besides housing and energy costs, the biggest consistent expenditure for most people is food.  Fortunately, it's also something you have a good amount of control over.  You can do things to save money on food while still eating well and eating healthy.

Step 1 is to limit eating out.  When you eat out, you pay for labor as well as food.  That's usually going to be more expensive than cooking at home.  You can get some fast food very cheaply, but you'll pay for it in terms of quality and healthfulness.  Remember, eating out at lunch counts too.  I know that I can easily spend $5.00 a day on lunch at work. (I have a subsidized cafeteria.) If you do the math, that's $1000 a year.  That's an emergency fund.

Step 2 is to limit waste.  Wasting food is the same as wasting money.  There are lots of ways to limit waste:

• First, buy only as much as you need, especially of things that go bad.  If 4 green peppers cost $1, the per pepper price is lower than 1 pepper for 45 cents.  But if you only need 1 and you don't use the other 3, you've actually wasted 55 cents.  If you want to buy in bulk, focus on buying things that have a longer shelf life, for example, salt, flour, sugar, dry milk, potatoes, onions.  Milk, tomatoes, lettuce are not good bulk buys unless you use a lot or you can plan several meals that use the same ingredients. 
• Second, watch out for recipes that use small amounts of unusual ingredients.  We all have a cabinet of unused ingredients.  You bought it for one recipe and never found another way to use it. There are some cookbooks I rarely use for that reason.  I'm just not going to make a dish that requires ingredients I'll use rarely.  I love Joanne Weir's approach to food, but her recipes use tons of relatively rare ingredients.  Compare that to Rachel Ray whose recipes, though far less sophisticated, use things I generally have or that I will be able to use regularly.
• Third, cook reasonable quantities.  What is reasonable depends on the dish.  If things freeze well or make good lunches, you can make more.  If something is only really good the day it's made, you want to make less of it.  Also, if you know you'll get tired of it before it's gone, make less.

Step 3 is to plan your meals and your grocery shopping.  The most efficient way to do this is to look at the grocery store ads, see what's on special, and build menus around that.  If roasting chickens are on sale, you can get two and have roast chicken one night.  At the same time, you can roast the other chicken and use it for a chicken caesar, chicken chilaquiles, or chicken and dumplings.  If pork tenderloin is on sale, you can sear and roast that, then mix shredded pork with rice noodles and cabbage with a shot of hot pepper sauce or make shredded pork barbecue sandwiches.  Those flavors are different enough that they won't bore the palate, but they use the sale items well.  Always take a list when you shop. It helps to avoid impulse purchasing.  Also, don't ignore cheaper cuts of meat.  there are lots of cuts of beef that are relatively inexpensive but very tasty, especially when braised.

Step 4 is to look at what you are eating.  Strangely enough, a lot of healthier ingredients are actually less expensive.  Oatmeal is healthier than commercially produced cereal and it's way cheaper per serving.  Filling a plate with vegetables is healthier and less expensive than large slabs of meat.  While I always recommend avoiding canned veggies, frozen vegetables are a healthy and tasty option and are frequent sale items.  You can also eat more cheap proteins — think beans and even eggs.  Especially in the winter, these foods are more filling and can make lovely meals.

Eat well.  Eat healthy.  Be happy.