In the past, leptin was the buzz word hormone that appeared in talks about hormone-related weight loss and weight gain. So far, leptin – a hormone that tells your brain to burn fat and tell your body when it's full – was thought to be the only hormone involved in weight loss.
"For decades, scientists have been trying to understand why it's so difficult to maintain the weight you've achieved after the sacrifices of a successful diet, and why it's so easy to regain lost weight," said Donato. "Leptin has been considered the most important hormone to date, saving energy when we're hungry."
During the study, the scientists saw that weight loss triggered an increase in growth hormone in the hypothalamus, making weight loss harder and increasing the intensity of hunger. Why do our bodies react that way? Energy saving.
"Energy conservation is so important to the organism that evolution has provided humans with two energy conservation mechanisms, one activated by leptin and the other by growth hormone."