A new study reveals that people with severe obesity face a significantly higher risk of severe or fatal infections. Drawing on data from over 540,000 individuals in the UK and Finland, the risk for grade 3 obesity is three times higher than for those of normal weight. Researchers warn of rising global obesity rates.
The study, led by Mika Kivimäki from University College London and Solja Nyberg from University of Helsinki, examined health data from two Finnish databases and the UK Biobank. It covered over 900 types of infections, from influenza to urinary tract infections, extending COVID-19 observations to other diseases.
Mild overweight increased the risk by 10 percent in Finland and 13 percent in the UK. For grade 1 obesity (BMI 30–34.9), it was 47 and 53 percent higher, respectively; grade 2 (BMI 35–39.9) doubled the risk; and grade 3 (BMI 40+) raised it 2.69- to 3.07-fold. Factors like gender, age, or socioeconomic status had minimal impact.
"It is plausible that obesity weakens the immune system's ability to defend against infectious bacteria, viruses, parasites, or fungi," The Lancet quotes Kivimäki. Potential causes include a nutrient-rich environment for microorganisms, insulin resistance, hyperglycemia, and chronic inflammation, though the study does not prove causal mechanisms.
Applied to the Global Burden of Disease study, for 2023 in Germany, 4,700 of 31,900 infection deaths (14.7 percent) were linked to obesity—lower than in the US (25.7 percent) or Spain (21.2 percent), but higher than in China (9 percent) or India (3.8 percent).
Nyberg warns: "As obesity rates rise globally, the number of deaths and hospital stays will increase." There is an urgent need for measures to support weight reduction and health maintenance.
