Study Finds Obesity-Related DNA Marks Persist in CD4 T Cells After Weight Loss

Weight loss may not immediately erase obesity-associated changes in the immune system, according to a 10-year study published in EMBO Reports. Researchers reported that helper T cells, also known as CD4+ lymphocytes, can retain molecular signs of previous obesity for years after body weight has been reduced.

The study, led by researchers at the University of Birmingham, focused on DNA methylation—chemical tagging that can influence how genes function. The team found evidence that some obesity-associated methylation patterns may persist for 5 to 10 years following weight loss.

The researchers described this persistence as an “obesity memory.” They suggest it could help explain why some health risks linked to obesity may remain elevated after a person returns to a normal weight. The study specifically identified possible effects on autophagy, the process cells use to clear damaged or unnecessary material, and immune senescence, a form of aging in the immune system.

To examine these changes, the team analyzed immune cells from several groups. The material included blood from people living with obesity who received weight-loss injections; people with Alström syndrome, a rare genetic disorder associated with early-onset childhood obesity; and matched healthy participants. Researchers also examined blood and fat tissue from people who completed a 10-week exercise intervention, as well as samples from normal-weight and obese participants with osteoarthritis undergoing joint-replacement surgery.

Additional experiments involved mice fed a high-fat diet and blood donations from healthy human volunteers. These models were used to investigate cellular mechanisms associated with immune dysregulation in obesity. The source material does not establish that the mouse findings translate into a human health benefit or treatment.

Professor Claudio Mauro of the University of Birmingham said the molecular changes may gradually fade with sustained weight-loss maintenance, potentially over five to 10 years, but emphasized that this timeframe requires further study. The researchers also identified possible therapeutic directions, including investigating whether drugs such as SGLT2 inhibitors could affect inflammation and the clearance of senescent cells in obesity. That proposal remains a research possibility, not an established treatment for reversing the reported changes.

The findings add an immune-cell dimension to the challenge of maintaining health after weight loss. They indicate that returning to a lower body weight may not immediately restore every molecular feature associated with immune function, while leaving unresolved how strongly these changes relate to individual disease risk and whether they can be safely reversed.