Obesity and Coronavirus: What is the Connection?

Being overweight is a serious risk factor for COVID complications


How deadly is the coronavirus?

The new coronavirus is highly contagious and the infection it causes (called COVID-19) can have serious complications and even lead to death. By mid-2020, there already are nearly 14 million documented COVID cases in the world, including 3.5 million in the US alone. The number of undocumented cases (meaning people who either don’t notice that they are infected or can’t get tested) is estimated to be even higher.

The documented global death rate so far is about 4%, meaning that 4 out of 100 infected people will die from a COVID infection. However, taking into account estimates for the number of undocumented COVID cases, the real mortality rate probably is between 0.5% to 1% and thus not far away from the common flu. These percentages vary from country to country. In some countries, the medical system initially was overrun by the virus, which left many patients without adequate treatment and thus raised the overall mortality rate. As doctors become more adept at fighting the virus and more equipment and drugs become available for treatment, the COVID death rate is likely to gradually decline in the future.  

There’s also a strong age factor: older people naturally are at a higher risk of dying or suffering serious complications than children or teenagers. Different studies from Germany, the UK, and the US indicate that for people in their 80s the mortality risk of COVID is about 8-12% whereas for people below age 20 it’s well below 0.5%. 

Underlying diseases also play an important role in how well a person will manage a COVID infection. Roughly 90% of COVID fatalities have at least one comorbidity (a secondary medical condition that worsens your chances of surviving COVID), including primarily high blood pressure, diabetes, heart issues, and cancer. Of course, these conditions are relatively common among older people. Therefore, to what degree these conditions worsen a COVID infection is still being figured out by scientists. It will still take many months, if not years, to fully understand this complex virus and disease.

Even the blood type is thought to play a role. Several European and Chinese studies have found that people with blood type 0 are less susceptible to getting infected by the virus and their symptoms will also be milder than in people with blood type A. Other scientists dispute these findings, though, and genetic factors also may matter for how serious an infection gets.   

How does COVID kill?

Like with fatal outcomes in other viral flu infections (the common flu, bird flu, swine flu, etc.), the most common cause of death is respiratory failure, which means people can no longer breathe and eventually suffocate. That’s why mechanical ventilation and administering oxygen to serious COVID cases is so important. The second most common cause of death from COVID is septic shock, where the body’s response to the infection gets out of control and the blood pressure drops to deadly low levels. Organ failures — often tied to existing conditions such as kidney or heart problems — are the third most common cause of death. 

How does obesity affect the course of coronavirus infection?

“Obesity” is a medical term to describe people whose body mass index (BMI) scores 30 or higher. For a person of average height (5’ 9”) this threshold typically starts at 200 lbs. For the same height, anything between 170 to 200 lbs is considered overweight but not yet obese and has a BMI of 25-30. Some 40% of the US population is considered clinically obese. Calculate your BMI here

Being overweight or obese poses serious health risks. It can affect everything from heart health to the functioning of the liver and kidneys. Obesity can lead to asthma, diabetes, some types of cancer, and erectile dysfunction. On average, a BMI of 30 to 35 over the course of one’s life reduces overall life expectancy by up to 4 years. For BMI 35 and higher, it can be up to 10 years.

It thus shouldn’t come as a surprise that obesity will also negatively affect one’s chances of overcoming a COVID infection. The COVID record so far shows that in people aged 55 and younger obesity is the most common risk factor for developing severe complications, in particular breathing and blood flow problems. A BMI of 30+ makes it 20-25% more likely that you won’t weather COVID easily and a BMI of 40+ gives it a 50% likelihood that you’ll need medical help, and most likely a hospital stay. 

Why can obesity worsen a COVID infection?

This question is still being investigated by the scientific community, but there are already some strong theories. People who are obese or overweight often have breathing difficulties even when healthy. This includes shortness of breath and a greater risk of asthma. The underlying cause is that the extra pounds of an overweight person is concentrated on the abdomen, right below the diaphragm. Every time you breathe, your diaphragm is moved down and then up again. The more body mass there’s to move with each breath, the harder breathing gets. As a consequence, the breathing difficulties caused by COVID more quickly lower the oxygen levels and weaken the body of an obese person than in one with normal weight.
Another potential impact of obesity on COVID infections is that the immune system is more likely to malfunction and overreact, which in turn can lead to a septic shock. Obese people are also more likely to have (or be on their way to getting) conditions like diabetes, high blood pressure, and chronic inflammations. All of these are risk factors for COVID complications.

There’s also the theory that the virus can gain easier access to your body via fat cells since fat cells produce more ACE2 proteins, which act as connectors to which the coronavirus hangs on to.
By how much exactly obesity raises the mortality risk of COVID isn’t known yet, but it does seem to lead to more severe infection, which can be life-threatening. Moreover, the longer you have to battle with the disease, the longer the recovery will take and there could be long-term damage to the lungs and other organs.   

As an obese person, how can I protect myself?

Given their higher risk profile, obese people need to take extra care to avoid a COVID infection and meticulously follow social distancing, mask use, and hygiene guidelines, as specified by the CDC and the WHO. If in doubt about whether you are taking enough precautionary measures, talk to your doctor or read up on the virus at the CDC COVID information page.  

Obesity can be a long-term killer even without COVID. So, if you haven’t done anything about those extra pounds yet, it’s high time you get started on a healthier lifestyle right away. The silver lining of the COVID pandemic is that we have more time to ourselves as we are spending more time at home. This gives you more time and focus to cook and eat healthier. You probably also have more time to work out. Even if the gym is closed, you can work out at home or go walking and jogging outside as long as you follow social distancing rules.



  • Katie Pearce / Published, and 2020. “Obesity a Major Risk Factor for COVID-19 Hospitalization.” The Hub, 1 June 2020, Accessed 16 July 2020.
  • Ellinghaus, David, et al. “Genomewide Association Study of Severe Covid-19 with Respiratory Failure.” New England Journal of Medicine, 17 June 2020, 10.1056/nejmoa2020283. Accessed 16 July 2020.
  • Dietz, William, and Carlos Santos-Burgoa. “Obesity and Its Implications for COVID-19 Mortality.” Obesity, 1 Apr. 2020, 10.1002/oby.22818. Accessed 16 July 2020.
  • Sattar, Naveed, et al. “Obesity a Risk Factor for Severe COVID-19 Infection: Multiple Potential Mechanisms.” Circulation, 22 Apr. 2020, 10.1161/circulationaha.120.047659. Accessed 16 July 2020.

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