Even mild obesity raises odds for severe Covid-19

  • Until now, studies on the effect of obesity on coronavirus patients have focused on the severely obese 
  • It, however, appears that any degree of obesity increases the risk of serious illness in Covid-19 patients
  • This could be because obesity triggers a 'chronic inflammatory state' in the body


Even mild obesity significantly drives up the risk for serious illness or death among Covid-19 patients, researchers from Italy report.

"Healthcare practitioners should be aware that people with any grade of obesity, not just the severely obese, are a population at risk," said study lead author Dr Matteo Rottoli.

"Extra caution should be used for hospitalised Covid-19 patients with obesity, as they are likely to experience a quick deterioration towards respiratory failure, and to require intensive care admission," added Rottoli, a senior assistant professor of surgery at the Alma Mater Studiorum University of Bologna.

'Guidelines need reassessing'

The finding is not the first to link obesity to worse Covid outcomes. However, most studies have focused on patients with a body mass index (BMI) of 40 or more, the threshold for "extreme obesity". And that's also the cutoff used for US and UK guidelines identifying people at greater risk.

But this new study of nearly 500 Italian patients hospitalised with Covid-19 in March and April suggests those guidelines need reassessing.

More than a fifth of the patients evaluated had a BMI of 30 or higher, meaning they were considered obese.

Mildly obese patients – those with a BMI between 30 and 35 – were found to face a 2.5-times greater risk for respiratory failure. They were also five times more likely to be admitted to an ICU, compared to non-obese patients.

And those with a BMI of 35 and up were 12 times more likely to die from Covid, the researchers found.

Chronic inflammatory state

Dr Marc Siegel, a professor of medicine at NYU Langone Medical Center in New York City, wasn't surprised by the findings.

He agreed that "obesity is clearly a huge risk factor for moderate-to-severe cases of Covid". The fact that this likely involves even the mildly obese "is in keeping with what we've been seeing", Siegel said.

But why is that so?

As a whole, "obesity has been widely recognised as a factor associated with impaired immunological response and pathogen defence," Rottoli explained. Driving that impairment, he said, is a kind of "chronic inflammatory state" triggered by obesity.

Recent research out of Henry Ford Hospital in Detroit (published in Radiology in May) highlighted obesity-related inflammation as a possible driver behind a three-times greater risk for blood clots in the lungs seen among obese Covid patients.

Again Siegel agreed. "Although we're all still studying this, Covid does seem to be an illness of inflammation," he said. And he stressed that all the health complications associated with obesity – such as high blood pressure, diabetes and heart disease – "themselves increase the risk for serious illness with Covid".

Weight loss the definitive answer

Rottoli added: "Obese patients have been proven to have a higher viral load and a longer time of virus shedding, compared to non-obese patients." This renders them more contagious for longer periods of time, he noted.

All of this is worrying news for the more than one-third of US adults who are obese and the one in 13 who are extremely obese, according to US health officials.

For obese individuals, Rottoli has two pieces of advice: Lose weight and be careful.

"In the mid- and long-term, weight loss is the definitive answer to reduce the risks in people with obesity," Rottoli said. In the meantime, those who want to avoid getting Covid "should take extra care, in particular regarding their social behaviour and distancing," by using masks and avoiding large gatherings and other risky situations.

The findings were published on 15 July in the European Journal of Endocrinology.

Image credit: iStock

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