Hormone found to potentially obstruct weight reduction efforts in study findings
A New Twist in Weight Loss: Growth Hormone's Unknown Role
Wondering if there's an alternate explanation for why shedding those pesky pounds is such a struggle? Scientists from the University of São Paulo may have found a surprising answer. In a recent study, they discovered a lesser-known role for growth hormone (GH) in the metabolic response to energy restriction during dieting.
For decades, we've known about GH - it's a hormone that helps with bone growth and plays a significant role in maintaining organs and tissues throughout our lives. Yet, researchers from Brazil have found an entirely unexpected function for GH: energy conservation during weight loss. Lead author José Donato Junior and his team published their findings in a leading journal.
When an animal (or human) reduces food intake, the body responds by conserving energy. This is critical since in the wild, calories can be scarce. Over the years, scientists have tried to pinpoint why weight often rebounds after dieting. Donato explains, "So far, leptin has been considered the main hormone that acts to conserve energy when we're hungry."
You're probably familiar with leptin. Fat cells produce this hormone, which interferes with hunger. However, when we lose weight, leptin levels in the bloodstream drop, and the result? Hunger kicks in. In some cases, individuals can develop this condition called leptin resistance, where they no longer respond to the hormone and are often ravenous.
But what if GH is the piece of the puzzle that's been missing?
"GH receptors are abundant in muscle, tissue, liver, and organs involved in metabolic growth," says Donato. "But what's new is that we found the brain is also packed with GH receptors."
To dive deeper, the researchers observed that, in response to restricted calories, leptin levels decrease, while GH levels increase. Curious to understand the connection, they focused on the hypothalamus - a region of the brain that regulates the autonomic nervous system, coordinates energy homeostasis, and governs food intake.
The researchers found a significant number of GH receptors in the hypothalamus, which activated a group of neurons that trigger food cravings and the hoarding of energy stores. By genetically engineering mice lacking the AgRP-specific GH receptor (AgRP GHR KO mice), they found that this group lost more weight during calorie-restricted periods.
Interestingly, the researchers also tried blocking GH receptors using a drug called pegvisomant. Once again, the energy conservation response was much less pronounced in the mice, leading to increased weight loss.
"GH is not just involved in metabolic growth," Donato concludes. "It also affects the metabolic responses that conserve energy when we're hungry or dieting. That's precisely the same role leptin plays."
With this new discovery, the researchers hypothesize that future treatments targeting GH receptors could potentially help with weight loss and obesity management. They have good reason to be optimistic - understanding the complex dance of hormones could lead to better weight-loss interventions and hopefully, easier weight control for all of us!
- In the field of endocrinology, a new role for growth hormone (GH) in weight loss is being explored, as Brazilian researchers have discovered that it aids in energy conservation during dieting.
- While GH is typically associated with bone growth and organ maintenance, recent research suggests that it also influences weight management and metabolic responses to calorie restriction.
- In a surprising finding, the study shows that the brain is packed with GH receptors, which, when activated, trigger food cravings and energy hoarding, potentially contributing to weight rebound after dieting.
- To test their hypothesis, the researchers genetically engineered mice lacking the AgRP-specific GH receptor and found that these mice lost more weight during calorie-restricted periods.
- The scientists also blocked GH receptors with the drug pegvisomant, leading to decreased energy conservation and increased weight loss, suggesting that targeting GH receptors could be a promising approach for weight loss and obesity management in the future.
