On March 23, 2025, a study from the Universidad Complutense de Madrid (UCM), published in the Journal of Molecular Science, reveals a promising discovery: melatonin not only helps with sleep but may also reduce visceral fat and prevent weight gain. Led by María Pilar Cano Barquilla, the study conducted on rats suggests that this hormone regulates fat metabolism without changing appetite. Here’s how it works and what it could mean for the future.
Melatonin vs. Visceral Fat: A Clock Under Control
Visceral fat, the fat that accumulates around organs and increases health risks, has a “biological clock” that melatonin can adjust. In Wistar rats, after 11 weeks of a controlled or high-fat diet—with or without melatonin—the researchers found that the treatment reduced triglyceride storage in mesenteric fat tissue. “There’s less visceral fat and less weight gain, without the rats eating less,” explains Cano Barquilla. The secret lies in how melatonin modulates lipolysis—the breakdown of fats—and its associated genes.
High-Fat Diet: The Enemy of the Rhythm
A high-fat diet disrupts this internal clock, promoting obesity by altering gene expression related to lipolysis. But melatonin seems to counteract this, keeping metabolism running smoothly. Blood tests showed changes in free fatty acids and glycerol over a 24-hour cycle, reinforcing the idea that biological timing matters.
What’s Next?
The team is not stopping here. “We will continue exploring how melatonin affects other tissues like the liver and muscles, and its role in insulin resistance linked to obesity,” says Cano Barquilla. Although the results in rats are promising, human clinical studies are needed to confirm whether the supplement you take to sleep could also help trim your waistline.
Why It Matters in 2025
On March 23, 2025, this study illuminates a hopeful path against obesity, a global problem that continues to rise. Melatonin, affordable and accessible, may be more than a sleep aid—it could be a metabolic ally. As science advances, this discovery encourages us to view our biological clock in a new light. Will you give it a try? For now, the rats say it works.
