FOR most of the last century, our understanding of the cause of obesity has been based on immutable physical law. Specifically, it’s the first law of thermodynamics, which dictates that energy can neither be created nor destroyed. When it comes to body weight, this means that calorie intake minus calorie expenditure equals calories stored. Surrounded by tempting foods, we overeat, consuming more calories than we can burn off, and the excess is deposited as fat. The simple solution is to exert willpower and eat less.

The problem is that this advice doesn’t work, at least not for most people over the long term. In other words, your New Year’s resolution to lose weight probably won’t last through the spring, let alone affect how you look in a swimsuit in July. More of us than ever are obese, despite an incessant focus on calorie balance by the government, nutrition organizations and the food industry.

But what if we’ve confused cause and effect? What if it’s not overeating that causes us to get fat, but the process of getting fatter that causes us to overeat?

The more calories we lock away in fat tissue, the fewer there are circulating in the bloodstream to satisfy the body’s requirements. If we look at it this way, it’s a distribution problem: We have an abundance of calories, but they’re in the wrong place. As a result, the body needs to increase its intake. We get hungrier because we’re getting fatter.