A Cleveland Clinic study shows that substantial weight loss can reduce an individual's risk of severe complications from COVID-19.

The study, published in in the journal, JAMA Surgery, shows that among patients with obesity, prior weight loss with basic surgery was associated with 60% lower risk of developing severe complications from a COVID-19 infection.

"Our study provides strong evidence that obesity is a modifiable risk factor for COVID-19 that can be improved through successful weight loss intervention," said Cleveland Clinic Bariatric & Metabolic Institute Director and study author, Ali Aminian.

Numerous studies have established obesity as a major risk factor for developing severe illness from COVID-19.

This is because obesity weakens the immune system, creates a chronic inflammatory state, and increases risk for cardiovascular disease, blood clots and lung conditions.

A total of 20,212 adult patients with obesity were included in this study.

A group of 5,053 patients with a body mass index (BMI) of 35 or greater who had weight loss surgery between 2004 and 2017 were carefully matched 1:3 to non-surgical patients, resulting in 15,159 control patients.

Compared to those in the non-surgical group, patients who had bariatric surgery lost 19% more body weight prior to March 1, 2020, the beginning of the COVID-19 outbreak in Cleveland.

Although the rate of contracting COVID-19 was similar between the groups, (9.1% in surgical group and 8.7% in the non-surgical group) participants in the weight loss surgery group experienced much better outcomes after contracting COVID-19 compared to those in the non-surgical group.

Researchers found that patients with a prior weight loss surgery had a 49% lower risk of hospitalization, 63% lower risk of need for supplemental oxygen, and 60% risk of developing severe COVID-19.

Although the exact underlying mechanisms are unknown, these data suggest that patients who underwent weight loss surgery were healthier at the time of contracting COVID-19 which resulted in better clinical outcomes.