Obesity is a growing health concern around the world and a known risk factor for disease. Several types of cancer, cardiovascular disease, and COVID-19 all show higher mortality rates in patients with higher body mass indices (BMI).

However, new research suggests the opposite is true when the focus shifts to infectious diseases. The “obesity survival paradox” shows that being overweight or obese actually provides increased protection against severe bacterial infections.

Scientists in Sweden performed a population-based study that observed nearly 2,200 adult patients admitted to the hospital with severe bacterial infections. They found that being overweight or obese increased the chances of survival in both the short- and long-term, 28 days and one year after hospitalization, respectively. In fact, while 26% of patients with a normal weight died within a year, only 9-17% of patients with higher BMIs died.

Surveys of other patient groups have shown similar results. Despite these findings, researchers are still unsure of why bodyweight impacts a patients’ response to infection. More studies are needed to investigate a possible link with immune system function and regulation.