Obesity increases risk of Covid-19 death by 48%, study finds

Obesity increases the risk of dying of Covid-19 by nearly 50% and may make vaccines against the disease less effective, according to a comprehensive study using global data.

The findings, which the lead researcher described as “scary”, show that the risks for people with obesity are greater than previously thought.

The study – a collaborative effort between the University of North Carolina (UNC), Saudi Health Council and World Bank – will increase pressure on governments to tackle obesity, including in the UK where Boris Johnson has put himself at the head of a drive to reduce the nation’s weight.

It emerged ahead of a report from the Institute for Public Policy Research that calls on the government to go further than its recent initiatives, which include restrictions on junk food advertising and supermarket offers.

The thinktank says a giant leap, akin to progress on sanitation in Victorian times, is needed to bring down obesity levels that shorten lives by causing heart conditions, strokes, type 2 diabetes and cancers, and impose a huge cost on the NHS.

It urges the government to employ a combination of taxes and subsidies, and proposes a new non-essential food levy of 8% on unhealthy foods that exceed a certain energy density or calorie count. Such taxes have worked in Mexico and Hungary, where people are eating less of such foods and manufacturers are reformulating their products to be healthier.

The prime minister hit out last year at “sin taxes” such as the UK’s sugary drinks levy, but his own spell in intensive care with Covid-19, which he blames on his weight, has convinced him that tough measures are needed to reduce obesity levels. It is understood that even taxes are no longer off the table.

The US and UK have some of the highest obesity rates in the world. US government data shows that more than 40% of Americans are obese. The figure in England is more than 27% of adults.

The new study from the University of North Carolina at Chapel Hill into the effects of Covid-19 on people with obesity, defined as a BMI over 30, finds they are at greater risk from the virus in every way. Their risk of ending up in hospital with Covid-19 increases by 113%, of needing intensive care by 74%, and of dying of the virus by 48%.

The study was led by Prof Barry Popkin, of the department of nutrition at the UNC’s Gillings Global School of Public Health, who said he was shocked by the findings. The risk of dying of Covid-19 for people with obesity was significantly higher than anyone had thought.

Q&A How to find out if you are obese and your BMI is a problem Show Hide Obesity is measured by body mass index (BMI), which for an adult is a ratio of weight in kilograms by height in metres squared. The NHS has an online calculator. It does not work for children who are still growing and it is often regarded as a blunt instrument for individuals, because some very fit people have bulky muscle tissue that will make them heavier. But for most people and for looking at populations as a whole, it is a useful indicator of healthy or unhealthy weight. Normal weight is a BMI of 18.5 to 25. Below that you are underweight, which is also unhealthy. Between 25 and 30, an adult is considered overweight. BMI of 30 to 40 is obese. Anyone with a BMI higher than that is considered severely or morbidly obese and in need of medical intervention, such as bariatric surgery. The categories are not exactly the same for people from black, Asian and other minority ethnic groups, who have a raised risk of obesity-related diseases such as type 2 diabetes with a BMI of 23 and a high risk at 27.5. You can also find out whether you are obese with a tape measure. Carrying fat around your stomach is a significant risk for heart disease, type 2 diabetes and stroke. To measure your waist, put the tape around the midpoint between the bottom of the ribs and top of the hips and breathe out naturally. If a woman’s waist is 80cm (31.5ins) or more or a man’s is 94cm or more, they would be advised to lose weight. A waist of 88cm or more for women or 102cm or more for men puts you at very high risk and you should speak to your GP. Sarah Boseley Health editor

“That’s a pretty big effect for me,” he said. “It is a 50% increase essentially. That’s a pretty high scary number. All of it is actually, much higher than I ever expected.”

The risk of being admitted to hospital for people with obesity was doubled, he said. “That, ICU admission and mortality are really high. They all shocked me, to be honest.”

The study, published in the journal Obesity Reviews, is a meta-analysis, bringing together data from many studies carried out around the world, including China, France, Italy, the UK and the US. Obesity is a global problem that no country has yet successfully tackled.

People with obesity often have underlying medical conditions that put them at greater risk from the coronavirus, such as heart disease and type 2 diabetes. Obesity can also cause metabolic changes, such as insulin resistance and inflammation which make it harder for the body to fight off infections.

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“Individuals with obesity are also more likely to experience physical ailments that make fighting this disease harder, such as sleep apnoea, which increases pulmonary hypertension, or a body mass index that increases difficulties in a hospital setting with intubation,” said the study’s co-author, Prof Melinda Beck.

Nor may a Covid-19 vaccine work as well in people with obesity, the authors say. “We know a Covid vaccine will have a positive effect on obese people, but we suspect from all our knowledge from tests on the Sars vaccine and the flu vaccine it will have a diminished benefit compared to the others,” Popkin said.

They had convinced the Centers for Disease Control, which oversees public health in the US, that people with obesity were not getting the full benefit of standard flu vaccines, he said. “We now have a stronger flu vaccine for overweight people.”

The recommendation was brought in this year after a long campaign. There is now an extra booster shot for people who are overweight and for elderly people, whose immune systems weaken over time.

Popkin said vaccine developers should look at the data from their clinical trials for the obesity effect, even where they have an overall benefit. “They might just then have to consider this and do some testing in the vaccine to get it to work better for obese people,” he said.