THE HUNGRY BRAIN

Obesity researcher and health writer Guyenet seeks an answer to why, “between 1980 and the present, the U.S. obesity rate more than doubled” despite our national obsession with dieting.

It is certainly not for lack of information, since there are thousands of self-help books on the subject of the relationship between diet and health and longevity. After exploring and rejecting a number of the proposed solutions, the author, who has a doctorate in neurobiology, concludes that it is not necessarily fats or refined sugar in our diets that are the culprits. Following in the footsteps of Daniel Kahneman’s Thinking, Fast and Slow (2011), Guyenet looks to the structure of the human brain and how it has evolved over time. “The brain’s thought processes can be roughly divided into two systems,” he writes. “System 1 is fast, effortless, intuitive, and unconscious, while system 2 is slow, effortful, rational, and conscious.” The first is impulsive and ruled by the brain’s reward system, so our conscious attempts to follow a strict diet are undermined by anticipations of tastiness “selected over millions of years” when food was scarce and difficult to procure. Putting food on the table can be hard work. In a world in which calorie-rich convenience foods are readily available, this presents more temptation. The gratification that these foods provide overrides feelings of satiation and encourages us to overeat. Guyenet explores the latest research on how insulin regulates fat storage, as well as the role of the neurotransmitter leptin, which controls appetite. He also finds a direct relationship between sleep loss and eating behavior; we often compensate by eating higher-calorie foods. Not getting enough regular, restorative sleep “increases the reward system’s responsiveness to food cues.” What we eat is largely a matter of individual choice, but the author supports regulating advertisements for unhealthy foods that target children.

A helpful guide offering encouragement to those looking for ways to lead healthier lives.