Michael Pollan, author of In Defense of Food: An Eater’s Manifesto and The Omnivore’s Dilemma: A Natural History of Four Meals, is professor of science and environmental journalism at the University of California, Berkeley.

Pollan says everything he’s learned about food and health can be summed up in seven words: “Eat food, not too much, mostly plants.”

Probably the first two words are most important. “Eat food” means to eat real food — vegetables, fruits, whole grains, and, yes, fish and meat — and to avoid what Pollan calls “edible food-like substances.”

Here’s how:

1. Don’t eat anything your great grandmother wouldn’t recognize as food. “When you pick up that box of portable yogurt tubes, or eat something with 15 ingredients you can’t pronounce, ask yourself, “What are those things doing there?” Pollan says.

2. Don’t eat anything with more than five ingredients, or ingredients you can’t pronounce.

3. Stay out of the middle of the supermarket; shop on the perimeter of the store. Real food tends to be on the outer edge of the store near the loading docks, where it can be replaced with fresh foods when it goes bad.

4. Don’t eat anything that won’t eventually rot. “There are exceptions — honey — but as a rule, things like Twinkies that never go bad aren’t food,” Pollan says.

5. It is not just what you eat but how you eat. “Always leave the table a little hungry,” Pollan says. “Many cultures have rules that you stop eating before you are full. In Japan, they say eat until you are four-fifths full. Islamic culture has a similar rule, and in German culture they say, ‘Tie off the sack before it’s full.’”

6. Families traditionally ate together, around a table and not a TV, at regular meal times. It’s a good tradition. Enjoy meals with the people you love. “Remember when eating between meals felt wrong?” Pollan asks.

7. Don’t buy food where you buy your gasoline. In the U.S., 20% of food is eaten in the car.