People with obesity are at 70 percent higher risk of serious infections, with one in ten infectious disease deaths globally potentially linked to obesity, according to a new study.
People living with obesity are at a 70 percent higher risk of severe cases of infectious diseases, a new study has found.
The probabilities of being hospitalised or dying from an infectious disease – such as flu, COVID-19, pneumonia, and gastroenteritis – rise among people with obesity, according to a new study published in The Lancet.
“As obesity rates are expected to rise globally, so will the number of deaths and hospitalisations from infectious diseases linked to obesity,” said the study’s author, Solja Nyberg from the University of Helsinki.
She added that, to reduce the risk of severe infections, as well as other health issues linked with obesity, policies that support healthy lifestyles and weight loss are urgently needed, including access to affordable, healthy food and opportunities for physical activity.
The study analysed data from over 67,000 adults in Finland and over 470,000 adults in the UK Biobank dataset to look at the relationship between obesity and severe infectious disease.
The researchers measured the participants’ body mass index (BMI) at the start of the study and classified them into three different groups: healthy weight, overweight, and obese.
People with obesity were later classified as class I (30–34,9 kg/m2), class II (35–39,9 kg/m2), or class III (≥40,0 kg/m2).
Participants were followed for an average of 13 to 14 years.
The study found that people with obesity had a 70 percent higher risk of hospitalisation or death from any infectious disease compared to people with a healthy weight, those with a BMI between 18.5 and 24.9
Researchers saw that the risk rose steadily as body weight increased. People with the most severe obesity – BMI ≥40 kg/m² – had three times the risk of people with a healthy weight.
"Our finding that obesity is a risk factor for a wide range of infectious diseases suggests that broad biological mechanisms may be involved, “ Mika Kivimäki, leader of the study at University College London, said.
He added that it is plausible that obesity weakens the immune system’s ability to defend against infectious bacteria, viruses, parasites, or fungi, which can result in more serious diseases.
Kivimäki noted, however, that additional research is required to confirm the mechanisms underlying these associations.
The study has some limitations. As an observational study, no direct cause-and-effect can be attributed to the associations. The authors also noted that, as the analysis relied on BMI, it did not fully capture other aspects such as fat distribution or metabolic dysfunction.
What does this mean on the global scale?
By applying the risk ratios in the results to global data on obesity rates and infection deaths, the researchers estimated that 9 to 11 percent of infection-related deaths worldwide could potentially be prevented by eliminating obesity.
The burden varies widely depending on the country. In the United States, 25.7 percent of infection deaths are linked to obesity, the highest number.
In Spain, the number is 21.2 percent, in the United Kingdom it is 17.4 percent, and in Germany 14.7 percent.
India and China showed the lowest burden, with 9 and 3.8, respectively.
Obesity in Europe
Obesity rates are rising across Europe.
About 17 percent of European adults are obese and 51 percent overweight overall, according to EU data, in what the World Health Organization (WHO) has called an “obesity epidemic.”
WHO Europe aimed to halt the increase in adult obesity at 2010 levels by 2025, but no European country met it, with rates up 138 percent since 1975.
Newer goals in the 2022–2030 Non-Communicable Diseases Action Plan include a 30 percent relative drop in mean BMI by 2030, including halting child obesity.
