Consumers are getting the message that they need to eat more local, organic and fair trade certified food. But, as I’ve mentioned before, they’re having trouble deciphering what exactly these terms mean. How fair is fair trade? What are the standards for organic? And, for that matter, how do you define local?

How about this for a solution, then: Eat a peanut butter and jelly sandwich. This is the simple proposal behind a new grassroots movement that’s building momentum with eco-minded consumers. The PB&J Campaign, as it’s called, doesn’t advocate eating just PB&Js, however. They’re pushing for people to consume more plant-based foods, since the production process creates significantly less greenhouse gases than their animal-based shelf mates. Instead of a hamburger or chicken nuggets, try a salad. It’ll conserve the equivalent of 2.5 pounds of carbon emissions, according to the campaign website.

There’s a lot of complicated science behind the campaign’s proposals, but the PB&J gang manages to sum things up pretty succinctly. This is a measure of not just how sophisticated the sustainability movement is, but how accessible it’s becoming. You don’t have to be a food nut or an activist to know what’s required to make a difference.

Supermarket retailers do a pretty good job of tapping into the various movements out there, like providing local and seasonal products. But they also need to understand the desires and attitudes that fuel these movements. Shoppers want to do their part to conserve energy and help the environment. They not only want the transparency that will help guide their choices — they want the message to be simple and compelling enough to act on.

Did you see the two-page Q&A in the current issue of Smart Money magazine conducted with Jim Skinner, CEO of McDonald’s? Here’s a bite:

Q: …. If you wanted to shift eating habits more, you could.

A: If the consumer wants it. We can sell anything we want, but people have to buy it. If you look at the quality of the products and balanced choices we have, we’ve done more than anybody in the industry. But if you can’t get your kids to eat vegetables, why is it my job?

The italics in the last sentence are mine, because that’s one heckuva interesting point. At first, it sounds arrogant and callous - typical Big Business thinking. But Skinner (whose leadership has doubled the company’s stock price since he took over four years ago) points out that McDonald’s buys 39 million pounds of apples a year, more than anyone else in the country. Sure, some of them go to make those deep-fried apple pies, but others go into salads and the kids meals as Apple Dippers.

But Mickey D’s is not going to go around shoving these products in people’s faces. In his comment, Skinner implicitly acknowledges a fundamental truth about all fast food: It’s where convenience and taste and price trump health — always. Remember, McDonald’s is a burger chain. Its iconic status prevents it from being anything else. Remember Wendy’s and that chain’s 10-month fruit bowl experiment in 2006?

Skinner puts it this way in the Smart Money interview: “It’s not my job to take away; it’s my job to add and say, here are some choices. You have to make the decision.”

Indeed. Here that, Los Angeles? The city council there is weighing a moratorium on new fast food restaurants in one part of the city where QSRs proliferate among low-income neighborhoods. The idea is to implement a year-long ban so civic officials can try and attract more healthful outlets.

Our question is, Why? Spend the money educating consumers about proper dietary habits. Invest in community supported agriculture and farmers markets. Highlight diet and exercise as part of the local school curriculum. Armed with these “options,” consumers will have the power to create more change than any city council could.

Read Skinner’s comments again, and you see he alludes to the true solution, even while defending his company’s nutrition leadership. Until consumers want to change, fast food venues like McDonald’s and Church’s won’t.