Waist fat may be a stronger indicator of developing severe coronavirus complications than having an obese body mass index (BMI).
Early research suggests the infection is mild in four out of five cases, but statistics have repeatedly flagged obesity as a risk factor for the disease COVID-19.
Carrying fat around the abdomen – known as an "apple" body shape – has long been linked to the onset of heart disease, type 2 diabetes and even certain cancers.
Italian medics have now revealed that so-called abdominal obesity is associated with more severe chest X-ray results in coronavirus patients.
Although the picture is still unclear, abdominal fat in particular may trigger inflammation that can cause serious damage throughout a patient's body.
Amid the pandemic, chest X-rays "have played a very important role in the early diagnosis and treatment of patients with suspected or confirmed infections", the medics wrote in the journal Eating And Weight Disorders – Studies On Anorexia, Bulimia And Obesity.
Coronavirus patients are often scored according to their X-ray to gauge the severity of their disease, with higher results being linked to a greater risk of death.
When it comes to diagnosing obesity, many have argued BMI is an inaccurate measurement for failing to take fat distribution into account.
"Location is the key when it comes to body fat," wrote the medics.
Obesity has been linked to widespread inflammation, with "excess abdominal visceral [around several vital organs] fat considered the main culprit".
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To better understand abdominal fat's role in the onset of coronavirus complications, medics from the walk-in clinic IRCCS Policlinico San Donato in Milan analysed the BMI, waist circumference and chest X-ray severity scores of 215 people hospitalised with the infection.
An obese waist circumference was defined as measuring 102cm or more around the belly button in men, and at least 88cm in women.
The patients were grouped according to their chest X-ray scores, with zero representing a normal lung function and 18 being the most severe.
Results – also presented at the virtual European Congress on Obesity – reveal the patients with abdominal obesity had an average X-ray score of nine or above, with eight considered to be high.
This is compared with a score of six among those who did not carry excess fat around their waist.
Overall, nearly three in five (59%) of those with abdominal obesity had a high X-ray score, versus just over a third (35%) with slimmer waistlines.
Perhaps surprisingly, there was no difference in the chest scans of the patients with an obese, overweight or normal BMI.
A patient's waist circumference and waist-to-height ratio "correlated more closely" with their chest X-ray score than their BMI, wrote the medics.
Overall, abdominal obesity was linked to a 75% greater risk of a high X-ray score.
In addition, asthma was found to raise the odds by 73%.
High oxygen saturation – the amount of the gas in the bloodstream – upon admission to hospital was linked to a 4% reduced risk of a high X-ray score, compared with those with low levels.
Off the back of their results, the medics believe people hospitalised with the coronavirus should routinely have their waist circumference measured.
"Patients with abdominal obesity should be monitored closely," they added.
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