People with obesity are 1.7 times more likely to be hospitalised or die from infection, a new overseas study finds, while those with severe obesity face 3 times the risk.
The paper in The Lancet looked at data from over half a million people in the UK and Finland over several years.
Based on global data, the paper estimates that roughly 10% of infection-related deaths worldwide could be linked with obesity, and that this increased to 15% during the COVID pandemic.
The link appeared across a wide range of infectious diseases, suggesting the broader effects of obesity like immune dysregulation and chronic inflammation contribute to increased risk, the authors say.
The Science Media Centre asked local experts to comment.
Associate Professor Lesley Gray, Department of Primary Health Care, University of Otago Wellington, comments:
“It is important to look for effective treatment and care of all people in all sized bodies. While I am still reading through the statistical findings from this paper, I note the authors conclude by recommending that greater attention is needed for larger bodied people and prevention of severe infections.
“Heightened risk from infectious diseases and large bodied people was reported for earlier pandemics, e.g. the 2009 H1N1 pandemic, although after adjusting for delayed access to antiviral treatment, there was no actual increased risk for large bodied people in that pandemic. One strategy is effective vaccination where available. For large bodied people, effective vaccination sometimes requires a longer needle to ensure the needle reaches the muscle (if the vaccination needs to be deposited into the muscle). However, in research I have conducted with colleagues globally and in New Zealand, we identified widespread under-utilisation of the correct needle length for large bodied people in COVID-19 vaccination.
“While it seems so simple for the authors to recommend in their conclusions that public health strategies aimed at preventing adiposity (body fatness) and evidence-based weight loss interventions should be implemented: we know that public health strategies over the last 30 or so years failed to produce sustained and effective prevention of body fat increase in populations. We also know that the body’s own regulation of body fat means that for large bodied people, most strategies are time limited and can lead to plateauing, and even higher levels of body fat once the intervention is stopped (including the new GLP-1 drugs that are being widely adopted).
“Importantly, many strategies adopted over that time increased weight stigma. Weight stigma itself is a chronic stressor and according to a recent clinical trial, weight stigma leads to an acute inflammatory body response in the person being subjected to the stigma.
“The landscape of inflammation and risk is complex and not easily treated, but important first steps involve the removal of barriers for timely early access to care, ensuring effective vaccination and treatments available for all body sizes, and importantly eradication of weight stigma in healthcare and across society.”
Professor David Murdoch, Chief Scientist, New Zealand Institute for Public Health and Forensic Science (PHF Science), comments:
“This very large study shows that adults with obesity are at substantially higher risk of becoming seriously ill or dying from infections. Importantly, the increased risk was seen across a wide range of infections, not just COVID-19, and rose steadily as body weight increased.
“Although this type of research cannot prove that obesity directly causes severe infections, the findings were consistent across two countries, different age groups, and many types of infection. They also fit well with what we already know about how obesity can affect the immune system, including reducing the body’s ability to fight infections and recover once someone becomes unwell.
“For New Zealand, these results are highly relevant. Obesity is common and increasing, and this study suggests its impact extends beyond long-term conditions such as diabetes and heart disease. It may also increase the likelihood that common infections become severe enough to require hospital care.
“The authors estimate that around one in ten infection-related deaths worldwide could be linked to obesity, with higher estimates during the COVID-19 pandemic. While these global figures are uncertain and depend on assumptions, they highlight the potential benefits of preventing and treating obesity.
“Overall, the study reinforces that supporting healthy weight through prevention and treatment could help reduce both chronic disease and the burden of serious infections on hospitals and health systems.”
Conflict of interest statement: “Also, Distinguished Professor at the University of Otago.”
Professor Wayne Cutfield, Professor in Paediatric Endocrinology, Liggins Institute – University of Auckland, comments:
“It is well known that the consequences of obesity are far ranging and serious and include common non-communicable diseases such as diabetes mellitus, heart disease, stroke, liver disease, respiratory disease and cancer. In the USA, obesity is recognised by a number of medical organisations as a disease, and no longer just a risk factor for disease.
“In this large association study, the apparent risk of obesity extends to severe infections resulting in hospitalisation and/or death. Much of what we understand about the risks of obesity are from association studies like this one, which do not prove cause and effect. It is not possible ethically or medically to conduct a clinical trial of serious infection risk in obese individuals.
“The prevalence of common diseases (diabetes mellitus, heart disease, hypertension) were notably lower than expected in the Finnish cohort of this study, raising the possibility of undiagnosed co-occurring conditions or obesity related diseases that may have also directly contributed to infection severity. Despite this caveat, the evidence provided by the authors suggests obesity probably influences infection severity in that: there is a “dose” related effect (greater obesity has an increased risk of severe infection), the findings are across 2 populations and there is a plausible biological explanation.
“These findings are timely in New Zealand as Pharmac considers whether Wegovy (semaglutide) should be funded for the treatment of obesity in adults and adolescents. The risk of severe infection adds to the long list of preventable or at least reducible obesity related diseases many New Zealanders face. Interestingly, during the Covid 19 epidemic, the SELECT trial of Wegovy for obese adults (with cardiovascular disease and without diabetes) led to fewer infection-related deaths.”
Conflict of interest statement: “None for this article.”