And a second team say they have found a way of switching off the chemical that makes us hungry. Together, the two studies could lead to potential new weight-loss drugs.
Your body hates dieting. After a diet, it frantically tries to build new fat to restore you to your “normal” size. This is why it’s hard to lose weight – and harder still to keep it off.
“Obesity is not a lifestyle disease. That’s the absolute opposite of what it is,” says Associate Professor Zane Andrews, a neuroscientist at Monash University.
“Throughout evolution we have naturally selected people who are better at becoming fat. Our genes have evolved to make us fatter.”
Over most of the course of human history, being fat has been good. Fat insulates us from cold winters and acts as a buffer against starvation. Our brains are happiest when we are a little tubby.
When we diet, our brains become very unhappy indeed.
The empty stomach starts to pump the appetite hormone ghrelin into the blood, clouding our minds with hunger. Go on a prolonged diet and AgRP neurons in the hypothalamus, specially designed to sense hunger, switch into starvation mode.