By Science Desk.
Obesity significantly increases the risk of severe illness or death from most infectious diseases, according to a new study of over half a million people. The research, published in The Lancet, found a 70% higher risk of hospitalization or death for those with obesity when contracting illnesses like the flu, COVID-19, pneumonia, and urinary tract infections.
International Study Links Obesity to Infection Severity
The study, led by researchers from the United Kingdom and Finland, as well suggests that approximately one in ten infectious disease-related deaths worldwide could be attributed to obesity. This finding highlights the growing public health concern of obesity and its impact beyond chronic diseases.
“Our findings suggest that people living with obesity are significantly more likely to become severely ill or die from a wide range of infectious diseases.
Given that obesity rates are projected to increase globally, so too will the number of hospitalizations and deaths from obesity-related infectious diseases,”
said Solja Nyberg, of the University of Helsinki.
To mitigate these risks, and address other health issues linked to obesity, researchers emphasize an urgent need for policies that promote healthy lifestyles and support weight loss, including access to affordable, nutritious food and opportunities for physical activity. Maintaining up-to-date vaccinations is also particularly important for individuals with obesity, according to Nyberg.
Study Details and Findings
The research stemmed from observations during the pandemic, when individuals with obesity faced a greater risk of hospitalization or death from SARS-CoV-2 infection. However, it remained unclear if this association extended to infectious diseases generally.
To investigate further, the study analyzed data from 67,766 adults participating in two Finnish studies and 479,498 individuals from the UK Biobank. Researchers examined 925 bacterial, viral, parasitic, and fungal infectious diseases.
Participants’ body mass index (BMI) was assessed upon entering the studies, and they were followed for an average of 13-14 years. The average age at the start of the study was 42 in the Finnish research and 57 in the UK Biobank cohort.
The analysis revealed that individuals with obesity – defined as a BMI of 30 or higher – had a 70% increased risk of hospitalization or death from any infectious disease compared to those with a BMI between 18.5, and 24.9.
For example, adults in the UK Biobank with a BMI of 18.5 to 24.9 had a 1.1% risk of experiencing a severe infection in a year, while individuals with obesity faced an annual risk of 1.8%.
The risk increased consistently with increasing body weight. Individuals with more severe obesity (BMI of 40 or higher) had a three times greater risk than those with a healthy weight.
Researchers also examined ten common infectious diseases in detail. In most cases, including the flu, COVID-19, pneumonia, and gastroenteritis, individuals with obesity were more likely to be hospitalized or die than those with a healthy BMI.
However, obesity did not appear to increase the risk of severe HIV or tuberculosis infections.
Mika Kivimäki, of University College London, suggested that the observed association may involve broad biological mechanisms. “We see plausible that obesity weakens the immune system’s ability to defend against infectious bacteria, viruses, parasites or fungi, leading to more severe illness,” he said. Further research is needed to confirm these underlying mechanisms.
But more research is needed to confirm the mechanisms underlying these associations.
The authors also utilized data on infectious disease mortality from the “global burden of disease” study. The analysis indicated that 0.6 million of the 5.4 million (10.8% or one in ten) global deaths from infectious diseases in 2023 were linked to obesity.
Data revealed significant differences between countries. In 2023, the United States had the highest proportion among high-income countries, with obesity linked to one-quarter of deaths from infectious diseases, while in the United Kingdom, it was linked to one in six deaths.
Vietnam had the lowest proportion among the countries analyzed (1.2%).
- The authors noted several limitations, including the study’s reliance on observational data, which cannot confirm causality. The Finnish and UK cohorts may not be representative of the general population, so generalization should be approached with caution.
