A few years ago I read a really great book that helped change my perspective on food. It’s called “In Defense of Food,” by Michael Pollan, and it takes a new look at the fundamental assumptions that many Americans make (without even realizing it) about our diets.

According to Pollan’s book, many Americans are suffering from health problems (ranging from high blood pressure to diabetes to heart disease, cancer and stroke) that are caused or made worse by the “Western diet” – full of fat, meat, salt, sugar and processed foods.

If it’s true that “you are what you eat,” too many Americans are becoming, well, “fat,” and “overly processed.”

None of this is good for our health, but it’s good for the “Big Food” marketers who sell all those snacks, soft drinks, pre-made meals and processed foods. Food marketing is a $32 billion a year industry in America – all these companies trying to get us to buy what they’re selling, whether it’s French fries or energy drinks or nutritional supplements. Michael Pollan argues that despite the good intentions of nutrition scientists and government regulators, most people are more confused than ever about what constitutes “healthy eating.” Which vitamins and minerals and nutrients should we take? Are eggs good for you or bad for you? Do we need to take extra fish oil with Omega-3 fatty acids? Will the “Mediterranean diet” help us lose weight? What about Japanese seaweed? All of these nutrition fads might make money for the food manufacturers, but they don’t really help us know how to eat better.

Instead of latching on to the latest fad, Michael Pollan suggests in “In Defense of Food” that people need to look back to something old: the “real” foods and whole foods (vegetables, plants, fruits) that our grandparents used to eat.

He poses three rules for eating: “Eat Food. Not Too Much. Mostly Plants.”

• “Eat Food:” Much of the highly processed “food” that people eat is not really “food” as our grandparents would have recognized it. Michael Pollan describes it as “edible foodlike substances,” whether it’s a box of crackers that contains 50 ingredients, or “cheese food product,” or “dairy beverages.” Michael Pollan proposes that people can improve their diets simply by only eating real food – things that they know are real and are not full of artificial ingredients.

• “Not Too Much:” Instead of contributing to a food system that produces more and more cheap, bad food, Michael Pollan proposes that we all eat less, but eat better. We need to think in new ways about how the food we eat relates to the larger impact on the environment that supports us all – for example, if people need to eat bacon at every meal (bacon strips with breakfast, bacon bits on salad, bacon cheeseburgers for dinner) that means that more hogs need to be raised, often in environmentally-unfriendly hog confinements that pollute the air and water. More demand for meat means more grain gets diverted from feeding hungry people to feeding cows.

• “Mostly Plants:” Instead of eating meat as the “main course” on the plate, we should try to fill our plates with vegetables, especially leafy greens. Michael Pollan talks in the book about the importance of eating “plants” instead of “seeds” – like wheat, corn and other grains.

Michael Pollan’s “In Defense of Food” can really change the way people look at the food they eat each day. It makes a compelling argument that we all need to re-evaluate how we nourish ourselves, and how we maintain a healthier planet for the long-term.