Obesity and coronavirus: how can a higher BMI increase your risk?Nachelle Geronimo
Obesity and coronavirus: how can a higher BMI increase your risk?
Experts call for more weight loss treatment in the UK as studies show obese people are more vulnerable
A ventilator in an ICU. Ventilating patients effectively is more difficult if they are obese, doctors say. Photograph: Murdo MacLeod/The Guardian
Less than a year ago, Boris Johnson was taking a stand. Milkshakes, he said, should not be taxed.
“If we want people to lose weight and live healthier lifestyles, we should encourage people to walk, cycle and generally do more exercise. Rather than just taxing people more, we should look at how effective the so-called ‘sin taxes’ really are, and if they actually change behaviour.”
Obesity was a problem before Covid-19, but this is an infectious disease that hits obese people disproportionately hard, no matter their income.
Countries with high obesity rates from western Europe to the US are struggling to keep people alive in intensive care units. Britain, long described as “the fat man of Europe” also has the highest number of Covid-19 deaths in Europe. Almost 30% of adults in the UK are classed as obese. The figure is nearly 40% in the US, where Covid deaths have topped 100,000.
It is striking, experts say, that wealthy countries appear to have higher mortality rates than impoverished ones. Africa so far has not experienced the explosion of deaths that Europe has. There will be many factors, and absence of good data collection will be one. But low rates of obesity, type 2 diabetes and the chronic disease of the heart and other organs are likely to play a part.
Prof Barry Popkin, a professor of nutrition at the University of North Carolina at Chapel Hill School of Public Health in the US, says obesity “weakens greatly our immune system”.
The European Centre for Disease Prevention and Control says 73% of critically ill patients with Covid-19 in Italy, Spain, Sweden, Switzerland and the Netherlands are obese.
In the UK, according to Prof John Wilding, the president of the World Obesity Federation, obesity doubles the chances of death.
The non-profit organisation is publishing a dossier of evidence and guidance about obesity in Covid-19 on its website on Wednesday, setting out what has been established so far.
According to a yet to be peer-reviewed study of the electronic health records of 17 million adult NHS patients, the risk of a coronavirus-related hospital death increases from between 1.5 to 2 times for people with a body mass index of 30, which is the lowest level of obesity, to more than 2 for those with a BMI of 40 or more. “It is a very significant increase,” says Wilding . “And the reasons for that are probably pretty complicated.”
Although not an intensive care doctor, Wilding says one of the reasons is the difficulty ventilating somebody who is obese.
“It’s much harder to ventilate you effectively if you have a higher bodyweight. The lung capacity for the body size is lower, so there’s less reserve in the system. So of course, if you do have a severe respiratory infection, that affects the ability of the lungs to help get oxygen into the blood. The system is going to have to work a lot harder for you than it is for somebody who is much lighter and much smaller.”
It could make sense to advise everyone who is morbidly obese to shield – but GPs do not always put people on the scales or keep a record. So there is no register of who they are.
When Johnson was admitted to St Thomas’ hospital in London with Covid-19, he was reported to have weighed 17-and-a-half stone (111kg), which would have given him a BMI of about 36. BMI is a ratio of weight to height: 18.5 to 25 is normal and 30 is obese.
Over 40 is morbid obesity – and the point at which people can be referred to specialist care and may be eligible for bariatric surgery to reduce their stomach size. Johnson was vulnerable when he was infected – and he appears to have recognised his weight was a factor.
“I’ve changed my mind on this. We need to be much more interventionist,” he told senior ministers and advisers, according to the Spectator’s political editor, James Forsyth.
This is exactly what doctors at the British Obesity and Metabolic Surgery Society (BOMSS) have been waiting to hear; they have long feared that the UK is not taking the condition seriously.
Hospitals deal with the consequences of obesity – such as soaring rates of type 2 diabetes, blindness and amputations – and the cost to the NHS is high. But the UK offers only a tenth of the stomach-reducing surgery that France does: 6,000 operations a year compared with 60,000.
Prof David Kerrigan, the president of BOMSS, and colleagues wrote an open letter to the prime minister to draw his attention to last year’s call by the Royal College of Physicians for obesity to be recognised as a disease – not a lifestyle choice.
“There has been a curious reluctance on the part of the NHS to grasp this particular nettle,” they said, adding that bariatric surgery to shrink the stomach and reduce appetite was often regarded as a “quick fix”.
But “a quick fix is precisely what is needed if we are to avoid needless suffering, ICU admission and death in patients with obesity who subsequently become infected with Sars-CoV-2”, they wrote to Johnson.
Like so much of Covid-19, it is unclear why people who are obese are at higher risk of severe illness.
Shaw Somers, a consultant bariatric surgeon and a former BOMSS president, says people who are overweight have what is known as a pro-inflammatory state.
“Excess fatty tissue, when it reaches a certain point, starts to secrete certain hormones which make your body think that it’s inflamed. When it becomes extremely severe, at very, very heavy weight, it is the thing that drives the damage to all their organs. Their body thinks it’s chronically inflamed and this just basically trashes a lot of their essential systems like the kidneys, the lungs, the heart, etc,” Somers says.
“With severe obesity, your immune system is working overtime. What we know from Covid is, those who do badly have an exaggerated inflammatory response that comes on after seven to 10 days. Their immune system goes berserk and kills them. And we think that obesity just amplifies it and just makes it much worse.”
People who are obese also fare worse if they get Sars, flu or pneumonia. The highest risk is with the highest BMI, but it is a sliding scale. Even those who are overweight, with a BMI of 25, are running health risks.
“If you look at the prime minister, for instance, his BMI is 36. So it’s not far from 40, where he’d be eligible for NHS treatment,” says Somers. “If his BMI is 36 and he got another illness like blood pressure or diabetes, he would be eligible for NHS treatment for his obesity.
“Even someone who is maybe a couple of stone overweight will have a degree of impairment of the body function and the degree of impairment of the resilience of their body. Because of that obesity, they may not be aware of it until they get serious illness like Covid-19, such as bad influenza. Then it will hit them.”
Somers says the UK should be treating far more people who cannot reduce their weight by themselves. It does not have to involve surgery. He talks about the gastric balloon, for example, which is swallowed in a deflated state and then inflated to the size of a grapefruit in the stomach. Four months later, it effectively disintegrates and is passed in the normal fashion.
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