People with obesity who develop COVID-19 are more than three times as likely to develop severe disease as someone of normal BMI, two studies show.

In a study of 383 consecutive patients with COVID-19 admitted to a hospital in Shenzhen, China earlier this year, progression to severe disease occurred in 39% of those who were obese and 29% of those who were overweight, compared with 19% of patients in the normal weight range.

The authors, led by the National Clinical Research Center for Infectious Diseases in Shenzhen, used definitions for normal BMI (18.5kg/m²– 23.9kg/m²), overweight (24-27.9kg/m²) and obese BMI (above 28kg/m²) applicable to an Asian population.

After adjustment for age, sex and comorbidities such as diabetes and hypertension, those who were obese had 3.4-fold odds of developing severe disease compared with patients with normal BMI, the authors wrote in Diabetes Care.