Obesity Linked to Increased Severe Infection Risk

New research suggests obesity could be associated with as many as 1 in 10 infection-related deaths globally.

Feb. 11, 2026 at 3:55am

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People with obesity have a significantly increased risk for hospitalization or death from severe infection spanning a wide range of infections, with the highest level of obesity associated with an approximately threefold higher risk. The study estimates that obesity may have been a causative factor in 0.6 million of 5.4 million deaths, or in about 1 in 10 (10.8%) of deaths from infectious disease worldwide.

Why it matters

Obesity is well known to be linked to a broad range of adverse health effects, and key among them is impaired immunity, which is speculated to play a key role in increasing the risk and severity of infection. The public health implications of these findings are considerable, as they suggest that preventing and treating obesity could significantly reduce the burden of severe infections and related mortality.

The details

The study pooled data on 67,766 adults in two Finnish cohort studies and 479,498 adults from the UK Biobank database. Overall, the analysis showed those with obesity had a 70% greater risk for either fatal or nonfatal severe infection compared with those of healthy weight. The association increased in a dose-response manner, with the highest risk among those with class III obesity (BMI ≥ 40), with a hazard ratio of 2.75 in the Finnish cohorts and 3.07 in the UK Biobank cohort. The higher risks were consistent across varying measures of obesity, demographic and clinical subgroups, and wide-ranging types of infections.

  • The Finnish cohort was assessed between 1998 and 2002, with a mean age of 42 years at baseline.
  • The UK Biobank cohort was assessed between 2006 and 2010, with a mean age of 57 years.

The players

Solja T Nyberg

First author of the study and a PhD from the faculty of medicine at the University of Helsinki, Finland.

Mika Kivimäki

Lead author of the study and chair of Social Epidemiology at University College London, England.

Iain M. Carey

A senior lecturer in epidemiology at the Population Health Research Institute, City St. George's School of Health and Medical Sciences, University of London, England.

Michaela R. Anderson

An assistant professor of medicine (Pulmonary, Allergy and Critical Care) at the Hospital of the University of Pennsylvania, Philadelphia.

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What they’re saying

“During the COVID-19 pandemic, people with obesity had a higher risk of being hospitalized or dying with the SARS-CoV-2 infection. However, it is in accordance with our results, that the risk for severe infections is of the same size for nearly all the examined pathogens.”

— Solja T Nyberg, PhD, faculty of medicine, University of Helsinki (Medscape Medical News)

“It is plausible that obesity weakens the immune system's ability to defend against the infectious bacteria, viruses, parasites or fungi, therefore resulting in more serious diseases.”

— Mika Kivimäki, Chair of Social Epidemiology, University College London (Press statement)

“The new findings are quite significant as they address evidence gaps around obesity and the risk of serious infections and estimate the impact globally.”

— Iain M. Carey, Senior lecturer in epidemiology, Population Health Research Institute, City St. George's School of Health and Medical Sciences, University of London (Medscape Medical News)

“These results underscore that preventing and treating obesity is critical not only for reducing cardiovascular mortality but also likely for lowering the risk of infection-related deaths.”

— Michaela R. Anderson, Assistant professor of medicine, Hospital of the University of Pennsylvania (Medscape Medical News)

What’s next

The judge in the case will decide on Tuesday whether or not to allow Walker Reed Quinn out on bail.

The takeaway

This case highlights growing concerns in the community about repeat offenders released on bail, raising questions about bail reform, public safety on SF streets, and if any special laws to govern autonomous vehicles in residential and commercial areas.