By Ray Bass

Hormones have a lot of control over our day-to-day functioning. They determine how we feel, how we think, and even to some extent how we look. So when it comes to losing or gaining weight, it’s not surprising to hear that hormones could have something to do with it. If you’re having trouble losing weight—growth hormone could be the culprit.

In a recent study from the University of São Paulo in Brazil, researchers found that growth hormone (referred to as GH) can act in a way that prevents weight loss. “Growth hormone has been known for decades,” said José Donato Junior, a professor at the University of São Paulo’s Biomedical Science Institute. “But our discovery shows it does a lot more than was thought.”

Specifically, scientists already knew that we have large quantities of GH receptors in our muscle, tissue, liver, and organs that are directly involved in growth metabolism—but they thought that was it. This study revealed that our brains are also full of growth hormone receptors, and that they play a large role in our metabolic responses.

“We found that brain GH is not only involved in growth metabolism but above all influences the metabolic responses that conserve energy when we’re hungry or on a diet,” Donato said. “This discovery has important implications in terms of understanding why it’s so hard to lose weight.”

In the past, leptin was the buzzword hormone that came up in conversations of hormone-related weight loss and gain. Until now, it was thought that leptin—a hormone that tells your brain to burn fat for energy and tells your body when it is full—was the only hormone involved in weight loss.

“For decades, scientists have been trying to understand why it’s so difficult to maintain the weight achieved after the sacrifices of a successful diet and why it’s so easy to regain the lost weight,” Donato said. “Leptin has hitherto been considered the main hormone that acts to conserve energy when we’re hungry.”

During the study scientists saw that weight loss triggered an increase in growth hormone in the hypothalamus, which makes weight loss harder and increases the intensity of hunger. Why do our bodies respond this way? Energy conservation.

“Energy conservation is so important for the organism that evolution has endowed humans with two energy-conservation mechanisms, one activated by leptin and the other by growth hormone.”

What this means for anyone trying to lose weight.

In terms of actionable next steps, it’s clear that both doctors and patients need to consider growth hormone levels when putting together a weight loss plan. This study shows that weight loss treatments based solely on leptin will not work—growth hormone has to be taken into account.

So if you’re struggling to lose weight and have sought or want to seek out professional help, ask your doctor to consider your GH levels. It could save both of you time, and hopefully make it easier to reach your healthy weight goals.