Thesis on biological mechanisms of anorexia nervosa
Anorexia nervosa is widely recognized as one of the most severe and complex eating disorders. In a new doctoral thesis from Karolinska Institutet, Jingjing Xu, PhD student at the Department of Molecular Medicine and Surgery, investigates the biological mechanisms underlying this condition.
What's the main focus of your thesis?
“My thesis focuses on the biological mechanisms of anorexia nervosa, one of the best-known and most severe eating disorders. My studies in the past four years have sought to understand why patients can maintain a low weight for extended periods of time. Multiple factors, including changes in the gut, blood, and brain, are believed to contribute to the so-called negative energy balance seen in anorexia nervosa,” says Jingjing Xu, PhD student in the Translational Psychiatry research group at the Department of Molecular Medicine and Surgery.
What are the most important results?
“We found that several short-chain fatty acids (products of gut microbiome metabolism) were reduced in both patients with, and those recovered from, anorexia, suggesting lasting changes in the gut. We also found a genetic association between mitochondria (often referred to as the "powerhouses" of the cell) and anorexia nervosa risk, potentially explaining the disrupted energy balance seen in anorexia. Furthermore, we identified changes in the hypothalamus, the body's "command center" for appetite and metabolic control. Specifically, we found signs of reduced clearance of hypothalamic neuronal connections by microglia (the brain's immune cells).”
How can this new knowledge contribute to the improvement of people's health?
“My thesis really highlights that anorexia nervosa is much more than a desire to be thin. The findings in my work advance our understanding of the biological nature of anorexia nervosa and further emphasize that it is not a patient choice but rather a genetic predisposition. They also pave the way for the development of evidence-based treatments that could potentially cure this devastating mental illness.”
What are your future ambitions?
“My doctoral research focused on the intersection of psychiatry, neuroscience, and metabolism. I am excited to continue exploring this field and developing my expertise to help alleviate the growing global burden of mental illness”, says Jingjing Xu.
Dissertation
Friday November 14, 2025 at 09:00, Inghesalen, Widerströmska, Tomtebodavägen 18