A Chemical Hunger (2021)

A Chemical Hunger opens by treating modern obesity as an unexplained historical shift. It contrasts the low obesity rates and average body sizes of Americans in the late 19th century with today’s much higher figures, noting that the sharpest rise began around 1980. The change is hard to explain through familiar accounts of richer food, less exercise, or aging: high-calorie foods existed decades earlier, and older people were historically no heavier than younger ones. Obesity has continued to rise in the United States and worldwide, despite public-health efforts.

The argument is that conventional dietary explanations struggle to account for the broader pattern. Hunter-gatherer and traditional societies remain lean despite diets ranging from sugar-rich to high-fat, heavily starchy, or extremely limited in variety; some eat as much or more sugar or fat as Americans. The piece also points to rising obesity among laboratory and wild animals, pets, and zoo animals, including cases where diets are controlled. Finally, rats become obese especially quickly when given “cafeteria diets” of appealing human foods, even when those diets have similar fat content to standard high-fat lab diets. Taken together, these observations suggest that something beyond calories, macronutrient balance, food variety, and exercise may have changed. The piece presents these findings as mysteries to be explained, rather than offering a settled cause.