Are you eating food, or what Pollan would call a “foodish product”? Just a few generations ago, our ancestors didn’t eat food that was engineered in a lab to have an eternal shelf life. Nor were their diets based on highly processed foods containing extra helpings of sweet, salty and fattening ingredients—ones that humans naturally crave and often consume to excess, leading to obesity, diabetes and other chronic diseases. As much as you can, buy food that exists in nature. It’ll contain the nutrients you need, and you’ll be unlikely to overeat it.