Study finds obesity increases risk of serious infections
A new study shows that obese people have higher rates of mortality and hospitalization from various infections caused by viruses, fungi, parasites and bacteria.
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A new study confirms that being overweight not only makes people more susceptible to chronic diseases like heart disease and diabetes, but it may also increase the risk of serious influenza and other infections.
The study, published today KnifeIt turns out that People with obesity may be more likely to die and be hospitalized from a variety of infections Caused by viruses, fungi, parasites and bacteria. Researchers analyzed health data from more than 540,000 people enrolled in databases in the UK and Finland and found that the risk of serious infections increased as body weight increased. These findings reinforce growing evidence that high amounts of excess fat can impair the body’s ability to fight infection.
“This was an incredibly important paper,” says Aubrey Gordon, an epidemiologist at the University of Michigan who was not involved in the new study. It “really shows that obese adults have a significantly higher risk of being hospitalized or dying from infection, and we’re talking about hundreds of different types of infections, not just COVID-19.”
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The study authors analyzed hospitalization and mortality data from time periods before, during, and after the peak of the COVID pandemic. They looked at infections such as influenza, COVID, and pneumonia, as well as HIV and gastrointestinal, urinary tract, and skin and soft tissue infections. In addition to body mass index, or BMI (a controversial measurement for obesity), they also took into account waist circumference and waist-to-height ratio, as well as other demographic information, including age, gender, ethnicity, education, and socioeconomic status. The team also determined baseline health status, controlling for conditions such as high blood pressure, metabolic syndrome, diabetes, heart disease, stroke and cancer.
Obesity was linked to an estimated 8.6 percent of infection-related deaths in 2018 (a time before the pandemic), 15 percent of such deaths in 2021 (a time during the pandemic), and 10.8 percent in 2023 (a time after the peak of the pandemic). And the higher a person’s BMI, the greater the risk of serious illness from infection. (A BMI of 30 and above is generally classified as representing obesity.) People with a BMI of 30 to 35 (about 30 pounds overweight) had a 1.5 times higher risk of serious infection than those with a lower BMI. And the risk was nearly three times higher in people with a BMI above 40 (about 80 to 100 pounds overweight). The study authors wrote that these findings were consistent across all three metrics of body size, as well as sociodemographic and lifestyle groups. And physician and obesity expert Samuel Klein of Washington University in St. Louis, who was not involved in the study, says data from populations in both the UK and Finland showed very similar results. “This is a major observation, and it is strong,” he added.
The findings are consistent with previous research. Gordon’s group demonstrated in 2018 that obese people were more susceptible to flu infection and that the virus took 42 percent longer to spread than people who were not obese. many studies And reports during the pandemic found that people with obesity were more likely to develop COVID and had a much higher risk of hospitalization and death from the disease.
In the new study, obesity had the strongest association with serious skin and soft tissue infections, but the data showed an increased risk across the board for almost every type of infection.
Biologically, this makes sense. For one thing, Gordon says, in some people, being overweight can impair lung function, which can worsen outcomes from infections, especially respiratory infections. People with obesity may also have metabolic or hormonal problems that can affect their ability to fight infection. But recent compelling evidence has emphasized that differences in immune responses.
Inflammation is a natural defense mechanism — but chronic uncontrolled inflammation can be harmful and make the disease worse, explains Klein. He says evidence shows that obesity increases chronic low-grade inflammation and also impairs the immune system’s ability to fight pathogens. Other preliminary research suggests that obesity may affect Quality and quantity of protective antibodieswhich capture pathogens and signal invading immune cells to target them.
The new findings suggest an association but do not show any clear cause and effect. Gordon would like to see more data on low- and middle-income populations, but she wouldn’t be surprised to see similar trends globally.
Gordon and Klein say the results may prompt people with obesity and their physicians to focus on faster treatments and prevention measures such as vaccines. In the study, the authors also emphasized policies to help people eat a healthy diet and engage in exercise.
“To reduce the risk of serious infections, as well as other health problems associated with obesity, there is an urgent need for policies that help people stay healthy and lose weight, such as access to affordable healthy food and opportunities for physical activity,” study author Solja Nyberg, of the University of Helsinki in Finland, said in a press release.
The relationship between weight and health is subtle—it is influenced by stigma, health care access, and individual biology as well as diet, exercise, and other lifestyle choices. And growing research shows that some people who are considered obese based on their BMI are metabolically healthy.
“There are certainly complex biological factors associated with obesity,” says Gordon. “But there are also really complex social and environmental factors that influence this.”
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