Scientists: obesity leaves a "trace" in immune cells

Obesity leaves a "scar" on the immune system that does not disappear even after weight loss — it persists for years and increases the risk of diabetes and cancer. This is the conclusion reached by the authors of a study published in the journal EMBO Reports.

A group of scientists from the University of Birmingham found that T-helper cells — key players in immune defense — retain a kind of "memory" of past obesity. This trace is formed through epigenetic changes: chemical marks become fixed on the cells' DNA through a process known as methylation.

Most alarmingly, these changes can persist for five to ten years after a person has brought their weight back to normal. Immune cells continue to function as if the body were still in a state of obesity. This disrupts tissue clearance processes, impairs inflammation regulation, and accelerates age-related decline of the immune system.

The study was based on blood and tissue samples from several groups of people: patients with obesity, volunteers who had undergone weight loss, participants in physical training programs, and individuals with rare genetic forms of obesity. In addition, the scientists analyzed data from experiments on mice and cell models.

The results were unequivocal: even after body weight normalization, the immune system continues to carry an "imprint" of the previous metabolic state. This means that the threat of developing diseases associated with obesity — including type 2 diabetes and several forms of cancer — may remain elevated for many years after weight loss.

According to the researchers, central to this process are disruptions in autophagy — the mechanism of cellular self-cleaning — and accelerated aging of immune cells. It is precisely these disruptions that form a lasting restructuring of the entire immune system.

The authors of the study emphasize that the findings do not mean that disease is inevitable, but they point to the critical importance of long-term maintenance of a healthy weight. Looking ahead, the scientists are exploring the possibility of developing therapeutic approaches capable of "rewriting" the immune memory of obesity and restoring normal functioning to the cells.