Understanding the Long-Term Impact of Obesity on the Immune System
Obesity is more than just a physical condition; it can have lasting effects on the body, even after weight loss. A recent study has revealed that the risk of developing serious health complications such as type 2 diabetes and cancer may not completely disappear, even if someone loses weight. This is because obesity causes a ‘tagging’ process on immune cells, which can affect them for years after weight loss.
The research, conducted by the University of Birmingham, highlights that the body can remember the impact of obesity for between five to ten years. This means that individuals may still be at risk of developing severe complications, even after shedding excess weight. Professor Claudio Mauro, co-lead author of the study, emphasized that short-term weight loss may not immediately reduce the risk of diseases associated with obesity.
The Study’s Methodology
To explore the long-term effects of obesity on the body, researchers collected blood samples from four different groups over a 10-year period. These groups included:
- Obese patients receiving weight-loss injections
- Individuals with Alstrom syndrome, a rare genetic disorder linked to obesity
- People who participated in a 10-week exercise programme
- Patients with obesity who had osteoarthritis and were undergoing hip or knee replacement surgery
In addition, the team studied mice on a high-fat diet and analyzed blood donations from healthy human volunteers. Their findings revealed that immune cells, known as helper T cells or CD4+ lymphocytes, carry a memory of obesity through a process called DNA methylation. This ‘tagging’ effect on DNA can lead to issues like reduced waste clearance and a less effective immune system for up to a decade, increasing the risk of metabolic diseases and cancers.
Implications for Weight Management and Treatment
Professor Mauro noted that maintaining weight loss for several years might be necessary, but further research is needed to confirm these findings. He also suggested that SGLT2 drugs, typically used to treat type 2 diabetes, heart failure, and chronic kidney disease, could be beneficial for individuals with obesity. These drugs help the body eliminate excess glucose through urine and have shown promise in supporting the immune system.
The Global Obesity Epidemic
Obesity affects over one billion people worldwide and continues to rise, especially in Europe. Factors contributing to this epidemic include unhealthy food environments, urban designs that discourage physical activity, and growing social inequality. In the UK, an estimated one in 50 adults are using fat jabs, with increased demand since the National Institute for Health and Care Excellence (NICE) approved Wegovy for NHS use in 2023.
Despite this, nearly two-thirds of adults in the UK are overweight, and more than a quarter are obese, affecting around 14 million people. According to the NHS, a BMI of 30-39.9 is classified as obese, while a BMI over 40 is considered severely obese.
The Health Risks of Obesity
Obesity is linked to numerous serious health complications, including:
- Type 2 diabetes
- Heart disease
- Breast cancer
- Bowel cancer
- Stroke
In Britain, over 18,000 preventable cancer cases are currently attributed to obesity, making it the second-largest cause of the disease after smoking.
Dr Belinda Nedjai, senior author of the paper from the Wolfson Institute of Population Health at Queen Mary University London, highlighted that obesity leads to durable epigenetic modifications that influence immune cell behavior. She explained that the immune system retains a molecular record of past metabolic exposures, which could have implications for long-term disease risk and recovery.
This research underscores the importance of not only losing weight but also maintaining a healthy lifestyle to mitigate the long-term risks associated with obesity.
