I kind of feel like I'm reaching for low-hanging fruit here, but so be it.
I read recently, and no, I can't remember where, so I can't cite it, that in the US, we now spend more treating obesity than on food. EDIT: Great minds, apparently... Sharon Astyk wrote about this same topic today right here. I swear I didn't read her post until after this one was published.
With all that we understand about nutrition, health, the dangers of carrying excess weight, the health consequences of poor dietary choices, we are still increasingly increasing. Now, I know that much of this has to do with lack of access to healthy food, lack of education about food, lack of education with regard to meal planning and preparation. I get that. But for someone like me, there's really no excuse. So while I hope that those other factors can be ameliorated, and am doing my small part to make that happen, I'm addressing myself here to others like myself - we who know, yet do not act.
Eat more vegetables and fruit. If they're expensive, make room in your budget. Leave the potato chips or bottled water out of your grocery basket, and get some veggies. If you drink coffee, make it at home and carry it with you in an insulated mug, instead of stopping for coffee at a premium. Use the funds toward actual food.
Plan ahead. It's a pain in the posterior up front, but having a meal plan is SO liberating! If you can't force yourself to plan one, then just grab a blank calendar page, or a blank piece of scrap paper if you don't care about pretty, and keep track of what you have for dinner for a week or two or four. Once you get some idea of what you *have* made, it's much easier to plan what you *will* make. If there's take-out in there, because you were tired or short of time, planning ahead can rescue you from those emergencies. Furthermore, if you make dinner at home, YOU control what goes into it. If you eat take-out, you almost certainly get lots more calories and fat. Plus it costs a lot more than cooking at home. Is time a challenge? Make friends with your crock pot. I know this sounds like a lot of work, but the relief of looking at the calendar at 6 AM and knowing what's for dinner is immeasurable. Sometimes it might mean chucking the fixings into the crock pot, but that's ok. It really doesn't take very long. (if it does, amend your recipe!) You have the bonus of being greeted by the scents of the food cooking as well - and that's supposed to increase your digestion... something about the smell causing your digestive juices to flow more abundantly. No, I can't remember where I read that, either. Good thing I'm not in grad school any longer!
In keeping with "plan ahead," make your time work for you. I've read over and over about how it's much more fuel efficient to do all your errand-running in one trip. It's also a LOT more time efficient. And, if you plan it right, you might even be able to plan your errands such that you can use your bike, or combine public transit with the shoe-leather express. By doing some of this kind of planning, you can free up funds (gas money), time (doing all your errands at once), and possibly even get some exercise in as well. You can re-direct the time and funds toward planning what you're going to eat - and the benefits snowball.
Now - so that you know that I have some cred in this regard, I'll share with you how I managed to keep my family fed decently while raising four children by myself and going to graduate school.
Every August and December, I dragged out a calendar, and planned meals for the entire semester. Once I finished the plans, I made a shopping list and bought everything I'd need (except for fresh produce and milk) and put it all in the freezer or pantry. I am absolutely positive that this planning enabled us to eat actual meals instead of cold cereal or sandwiches! Yes, it was kind of a nuisance. Yes, it was a pretty large expenditure up front (which could be mitigated by following weekly grocery store flyers and stocking up on staples when they're on sale). But it was totally worth it. The money I didn't spend on pizza or Chinese take-out more than made up for the initial outlay.