CLEVELAND - More than 70% of American adults are overweight or obese, which health experts said can impair the immune system and increase the risk of serious illness from the coronavirus.

"COVID-19 has been a wake-up call that's shown the health consequences of obesity," said Dr. Ali Aminian, the director of the Bariatric and Metabolic Institute at Cleveland Clinic.

Aminian and his colleagues studied 363 COVID-19 patients. Some had a past history of weight loss surgery; others did not have surgery and had a BMI of 40 or more at the time they tested positive for COVID-19.

"We found that, in patients with severe obesity, 42% required hospital admission after contracting COVID," Aminian said, "however, in group of patients who had bariatric surgery before, only 18% required hospital admission after COVID-19."

Doctors said 13% of the patients without surgery were admitted to the ICU, 7% needed ventilators, and 2% died. None of the patients who had bariatric surgery was admitted to the ICU, none needed ventilators, and none died.

Doctors said the results suggest that, after weight loss, patients become healthier and are better able to fight the virus.

Aminian said if the results are confirmed by future studies, doctors can add this to the list of health benefits of bariatric surgery.