Ghrelin is your hunger gremlin. It is produced in your stomach and, like many fat-loss hormones, works with your brain to signal that you are hungry. Reducing calories, in an effort to lose weight, causes an increase in ghrelin. Even after 12 months of a reduced-calorie diet, research shows that ghrelin levels stay elevated. In other words, your body never adapts to eating less and constantly sends the “I’m hungry” signal, which is why maintaining weight loss is often harder than losing it in the first place.
The good news: Intense exercise decreases ghrelin levels, making it a key component to fat loss and weight maintenance.