Surprisingly, the risk of being overweight was even greater than that linked to obesity. Overweight patients were 40 percent more likely to die than healthy-weight patients, while obese patients were at 30 percent greater risk, compared with the healthy-weight patients.
The findings clearly demonstrated an increased risk of severe Covid-19 in anyone with a B.M.I. of 25 or above, according to the authors of the study, Dr. Mohamed Rami Nakeshbandi, an assistant professor of infectious diseases at SUNY Downstate Health Science University, and Rohan Maini, a medical student.
But while obesity increased the risk of death for men, it did not do so for women, they noted. (Other studies have also reported this disparity.)
The British study examined lifestyle risk factors among 387,109 men and women, 760 of whom had Covid-19. People with the virus who were overweight were roughly 30 percent more likely to be hospitalized than those of healthy weight; those who were obese were about twice as likely, compared with healthy-weight individuals.
The study, published in July in the journal Brain, Behavior and Immunity, also looked at factors like smoking, alcohol consumption and levels of physical activity, and concluded that moderate exercise reduced the odds that an infected person would be hospitalized.
“Socially distanced physical activity may be a good intervention,” said Mark Hamer, a professor of sports and exercise medicine at University College London and an author of the paper, said in an email. “It gives immune protection, and also helps with weight loss.”
Physical activity, which has been extensively studied, can reduce the risk of developing chronic conditions linked to excess weight, like diabetes and high blood pressure. But it won’t entirely eliminate the risk of impaired immune function and heightened inflammation, Dr. Popkin cautioned.