You’d think we’d be dieting pros by now. There are countless experts telling you they know the secret to getting slim by eating this or avoiding that. And then there’s the old “calories in versus calories out” equation that seems so simple at the surface, but is much harder when put in practice. And with 45 million Americans dieting each year and most people failing at those diets, there much be so much more going on underneath the calls to snack on kale chips and forget the calls of Little Debbie.
At the heart of the matter is a little thing called “set point weight,” says Stephan Guyenet, PhD, author of The Hungry Brain. “Body weight is regulated by the brain. If you don’t know that, you’re going to be surprised when your brain and body start fighting back against weight loss,” he says.
This is at the heart of why diets don’t work, says Sandra Aamodt, PhD, (appropriately) the author of Why Diets Make Us Fat. “Whenever your weight changes too much, your brain will intervene to push it back to what it thinks is the correct weight for you. And you might not prefer the same weight your brain prefers. Many of us don’t,” she says.
Guyenet likens the entire process to a thermostat. In your house, this device measures the temperature in your home and helps regulate it so that it stays stable. When the temperature goes up, the heat goes down (or the ac turns on), and vice versa. In your brain, your thermostat is in the hypothalamus. “Your hypothalamus will activate physiologic and behavioral responses to maintain your body temperature. For instance, if you’re cold, you may shiver or put on a sweater,” Guyenet explains.