A groundbreaking study from researchers at McMaster University has uncovered a surprising link between body fat and anxiety. Published on April 15, 2025, in the journal Nature Metabolism, the study offers new insight into how our physical and mental health are connected—especially through the role of fat tissue, also known as adipose tissue.
Anxiety and obesity are both rising around the world, and scientists have long suspected that these two conditions might be linked in more than just a surface-level way. This new research shows that our body’s fat stores don’t just passively hold energy. In fact, they can actively influence our mood and mental health.
The research team, led by Professor Gregory Steinberg, discovered that when we’re under stress, our bodies go into “fight or flight” mode. This is the body’s natural way of preparing to face danger. As part of this process, fat cells start breaking down fat in a process called lipolysis. This is usually meant to provide quick energy for the body to use.
But the researchers found that this fat breakdown also causes something else: it triggers immune cells within the fat tissue to release a hormone called GDF15 (short for Growth Differentiation Factor 15). Once released, GDF15 travels to the brain, where it can increase feelings of anxiety.
To test this idea, the researchers carried out detailed experiments with mice. They put the animals through behavioral tests to measure anxiety-like behavior, while also analyzing their body tissues to track the biological changes happening in their fat cells and brains.
What they found was a clear chain reaction—from stress to fat breakdown to hormone release to anxiety behavior.
Dr. Logan Townsend, the first author of the study, explained that this discovery could change the way we think about anxiety and how to treat it. “By understanding how stress-induced changes in fat cells influence anxiety, we can start to explore new ways of treating anxiety—ones that focus on the body’s metabolism instead of just the brain,” he said.
This could be particularly important for people who don’t respond well to current anxiety treatments, such as medication or therapy. If new treatments could target the GDF15 hormone or the processes in fat tissue that trigger its release, it might offer a more direct and effective way to help.
Interestingly, some pharmaceutical companies are already working on medications that block GDF15 to treat cancer-related weight loss. These same medications might also be useful for treating anxiety, according to the McMaster researchers.
Professor Steinberg, who is also a Canada Research Chair and co-director of McMaster’s Center for Metabolism, Obesity and Diabetes Research, emphasized the bigger picture: “This study highlights just how closely connected our physical and mental health are. It’s not just about what happens in the brain—what happens in our fat tissue also matters.”
In summary, this research shines a light on a new biological pathway that links stress, fat metabolism, and anxiety. It adds to a growing body of evidence showing that the systems in our body don’t work in isolation.
Our fat cells, once thought to be just energy storage, may play an active role in shaping how we feel. These findings could pave the way for more targeted and effective treatments for anxiety—by looking beyond the brain and focusing on how the body responds to stress at a metabolic level.
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The research findings can be found in Nature Metabolism.
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