Hormonal Discovery Potentially Impedes Weight Reduction in Individuals
Uncovering a Surprise Role: Growth Hormone and Energy Conservation in Weight Loss
In an intriguing turn of events, scientists from the University of São Paulo in Brazil have discovered a new function for growth hormone (GH) - conserving energy during weight loss.
You've heard about GH, right? It's been around for ages, affecting bone growth and maintaining organs as we grow and age. But it looks like GH has been keeping a secret: it's involved in energy conservation when we're losing weight.
José Donato Junior and his team published their findings in a well-known journal. You know, the one that publishes all the heavy-hitting scientific stuff.
When an animal's food intake is restricted, its body responds by saving energy. This is crucial in the wild, where finding food can be a struggle. But this energy conservation makes weight loss harder, and for years, researchers have been trying to figure out why.
Hormones and Weight Loss: A Dance
You might already be familiar with leptin, the hormone that plays a part in the body's response to weight loss. Fat cells produce leptin, which curbs hunger. Losing weight means a drop in leptin levels, making us hungrier. Some people can develop leptin resistance, which means they no longer respond to the hormone and feel hungrier more often.
As Donato explains, "Leptin was thought to be the main hormone that helps the body conserve energy when we're hungry." But despite our growing understanding of leptin, it hasn't led to successful weight-loss interventions. So, this study asks whether GH might be a missing piece of the weight-loss puzzle.
"GH receptors are found in large quantities in muscle and tissue, the liver, and organs involved in growth metabolism. However, what's unexpected is that the brain is brimming with GH receptors too,” says Donato.
The scientists found that leptin levels drop in response to reduced food intake, while GH levels increase.
GH in the Hypothalamus: The Energy Controller
The scientists found an abundance of GH receptors in the hypothalamus, a region of the brain that regulates automatic functions like breathing and digestion. It also plays a crucial role in energy homeostasis - the regulation of energy expenditure and food intake.
In the hypothalamus, a group of neurons produce agouti-related protein (AgRP). When these neurons release AgRP, appetite increases, and the body holds onto its energy stores more tightly.
The researchers discovered that GH receptors in the hypothalamus activate these neurons, triggering the release of AgRP.
To better understand GH's influence on AgRP neurons, the scientists created a strain of mice that lacked the AgRP-specific GH receptor (AgRP GHR KO mice). When deprived of food, these mice showed less reduction in energy expenditure than normal mice. As a result, they lost more weight.
In another experiment, the researchers used a drug called pegvisomant to block GH receptors. Again, energy expenditure decreased significantly less when mice were food-deprived.
"GH influences metabolic responses that conserve energy when we're hungry or on a diet," concludes Donato. "In other words, we discovered that weight loss triggers an increase in hypothalamus GH levels, which activate AgRP neurons, making weight loss more challenging and intensifying the sense of hunger. That's precisely the same role leptin plays."
This research could lead to new approaches for facilitating weight loss and improving the efficacy of obesity treatments, targeting GH receptors and associated metabolic pathways. Bon appétit to weight loss, and here's to a healthier future!
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- The study, published in a renowned scientific journal, reveals that growth hormone (GH), traditionally associated with bone growth, also plays a significant role in energy conservation during weight loss.
- In the brain's hypothalamus, a region responsible for energy homeostasis, GH receptors have been found to activate neurons that increase appetite and conserve energy.
- This activation, triggered by an increase in GH levels during weight loss, makes weight loss more challenging, intensifying the sense of hunger, similar to leptin's role.
- By understanding GH's influence on energy metabolism, researchers are hopeful that new approaches for facilitating weight loss and improving obesity treatments may emerge, targeting GH receptors and associated metabolic pathways.
- The deprecated notion that GH only affects bone growth and organ maintenance has been challenged by this surprising discovery in the realm of weight management and health-and-wellness, particularly in relation to nutrition and medical-conditions like obesity.
