Global study links obesity to about 1 in 10 infection deaths

A major international study published in The Lancet has found that just over one in every 10 deaths from infectious diseases worldwide can be linked to obesity, highlighting a significant global public health challenge. Researchers analysed health and mortality data from more than 540,000 adults in the UK Biobank and Finnish cohorts, tracking participants over more than a decade to investigate how body weight affects infection outcomes.

Obesity Raises Infection Severity & Death Risk

People with obesity — defined as a body mass index (BMI) of 30 or higher — were found to be roughly 70 % more likely to be hospitalised or die from infections than those with a healthy weight. This elevated risk held across a broad range of infections, including flu, pneumonia, COVID-19, stomach and urinary tract infections. The danger rose steadily with increasing BMI; individuals with the most severe obesity (BMI ≥ 40 kg/m²) faced about three times the risk of serious infection compared with healthy-weight adults.

Burden Varies by Country & Region

When the research team applied their findings to Global Burden of Disease mortality data, they estimated that obesity may have contributed to approximately 0.6 million of the 5.4 million infectious disease deaths in 2023 — about 10.8 % globally. The impact, however, differed between nations:

• In the United States, obesity was linked to roughly one in four infectious disease deaths,
• In the United Kingdom, about one in six deaths were obesity-associated,
• Countries with lower obesity prevalence, such as Vietnam, showed notably lower proportions.

Why Obesity Increases Infection Risk?

Scientists suggest that obesity may weaken immune defences, leading to poorer outcomes from infections. Chronic inflammation, metabolic disturbances, and impaired immune responses are among the possible biological mechanisms being explored. However, the observational nature of the study means it can’t prove direct causation — only a strong association.

Public Health Implications & Recommendations

With global obesity rates rising, researchers warn that the number of infection-related hospitalisations and deaths linked to excess weight may grow if preventative efforts are not strengthened. Experts recommend policies that support healthy lifestyles, such as improving access to nutritious foods, encouraging physical activity, and promoting vaccination, particularly for people with obesity.

Key Takeaway

The research adds to the evidence that obesity isn’t only a risk factor for chronic conditions like diabetes and heart disease — it also significantly influences outcomes from acute infectious diseases, underscoring the importance of weight management as part of comprehensive public health strategies.