Fast food imagery
Some of this book literally takes place in a McDonalds, because Pollan takes his family to eat there after learning everything he did about their farms and their supply chain. He realizes that the aesthetic experience of eating at McDonalds is so universally positive, because the food is indescribably tasty, that he doesn't feel obligated to scrutinize the company or its food. After all, as the imagery of the restaurant suggests, it is a happy experience.
Nature and instinct imagery
Another portion of the book uses the imagery of the flora and fauna of the wilderness nearest to where Pollan lives. By staying local, he hopes to become an expert on what is and isn't edible in the woods, for instance, and he notices that McDonalds isn't the worst thing on the planet one could eat. In nature, there are flowers, berries, fruits, and mushrooms that, if eaten, would literally kill him. The natural imagery is laced with the threat of death.
The imagery of the human as animal
Through the scientific depictions of human instinct, Pollan shapes a mental construct about the human. Instead of seeing the human for its social and linguistic aspects, he encourages his reader to view the human as an animal, because the human is an animal, scientifically speaking, and therefore, we can study the nutrition of a human for its biological aspect. He describes humans through instinct, desire for basic needs, and through the lens of death, because all animals die—and because many of his concerns in the book are related to early death in obese people and people with heart problems.
