One surprise is how deeply the food system is implicated in climate change. I don't think that has really been on people's radar until very recently. 25 to 33 percent of climate change gases can be traced to the food system. I was also surprised that those diseases that we take for granted as what will kill us - heart disease, cancer, diabetes - were virtually unknown 150 years ago, before we began eating this way.

Were the walls of our meat industry to become transparent, literally or even figuratively, we would not long continue to raise, kill, and eat animals the way we do.

There's a lot of research that suggests that organic yields are close or superior to conventional yields depending on factors like climate. In a drought year an organic field of corn will yield more - considerably more - than a conventional field; organic fields hold moisture better so they don't need as much water. It simply isn't true that organic yields are lower than conventional yields.

In addition to contributing to erosion, pollution, food poisoning, and the dead zone, corn requires huge amounts of fossil fuel - it takes a half gallon of fossil fuel to produce a bushel of corn.

Avoid foods you see advertised on television.

Oil companies have gas stations. There's this whole huge structure that is about finding a new liquid for the tank. And the idea that maybe there shouldn't be a liquid, that maybe the best is an electrical grid, a sustainably powered electrical grid that we all plug into, that doesn't sit well with oil companies.

Rule No. 12: shop the peripheries of the supermarket and stay out of the middle.