Understanding the Long-Term Impact of Obesity on the Immune System
Obesity is a growing global health concern, with more than one billion people affected worldwide. While weight loss can improve overall health, a recent study has revealed that the risk of developing serious complications such as type 2 diabetes and cancer may not completely disappear after losing weight. This discovery highlights the long-lasting effects that obesity can have on the body, particularly on the immune system.
Researchers from the University of Birmingham found that obesity triggers a ‘tagging’ process in immune cells, which can affect them for years even after someone has lost excess body fat. This means that individuals may still be at risk of developing severe health issues despite successful weight loss.
The Role of Immune Cells in Obesity-Related Health Issues
The study focused on immune cells known as helper T cells or CD4+ lymphocytes. These cells play a crucial role in protecting the body against infections and diseases. However, the research showed that these cells carry a memory of obesity through a process called DNA methylation. This tagging effect on DNA can lead to problems such as reduced waste clearance and a less healthy immune system for up to a decade.
Professor Claudio Mauro, co-lead author of the study, explained that short-term weight loss may not immediately reduce the risk of some disease conditions associated with obesity. He emphasized the need for further research into these findings and suggested that maintaining weight loss over several years could be essential for reducing long-term health risks.
Study Methods and Findings
To analyze the long-term effects of obesity, researchers collected blood samples from four groups of people over a 10-year period. This included obese patients taking weight-loss injections, individuals with Alstrom syndrome, participants in a 10-week exercise programme, and those undergoing hip or knee replacement surgery due to osteoarthritis.
In addition, the researchers studied mice on a high-fat diet and examined blood donations from healthy human volunteers. Their findings revealed that the ‘tagging’ effect on immune cells can lead to serious complications such as metabolic diseases and cancers.
Potential Treatments and Future Research
The study also explored the potential use of SGLT2 drugs, which are typically used to treat type 2 diabetes, heart failure, and chronic kidney disease. These drugs trigger the body to release excess glucose in the urine and have shown promise in helping the immune system in individuals with obesity.
Despite the availability of weight-loss treatments, nearly two-thirds of adults in the UK are overweight, and more than a quarter are obese. In the UK, a BMI of 30-39.9 is classified as obese, while anything above 40 is considered severely obese.
Obesity has been linked to various serious health complications, including type 2 diabetes, heart disease, breast cancer, bowel cancer, and stroke. More than 18,000 preventable cancer cases in Britain are currently associated with obesity, making it the second biggest cause of the disease after smoking.
Implications for Public Health
Dr Belinda Nedjai, senior author of the paper, highlighted that obesity is associated with durable epigenetic modifications that influence immune cell behavior. This suggests that the immune system retains a molecular record of past metabolic exposures, which may have implications for long-term disease risk and recovery.
As obesity continues to rise across Europe, fueled by unhealthy food environments, urban design that discourages physical activity, and widening social inequality, it is crucial to understand the long-term impact of weight loss on the body. The findings of this study emphasize the importance of maintaining weight loss over several years and the need for further research into effective strategies for managing obesity-related health risks.
