Is being overweight a COVID-19 risk?‍

For most people, COVID-19 is a mild disease. But for others, it can become life-threatening.

Since the start of the pandemic, researchers around the world have been working hard to find out who is most at risk from the disease and what we can do to protect them. 

Age was one of the first factors to emerge, with older people at greater risk of developing severe symptoms or dying as a result of coronavirus infection than younger folk. 

People with underlying health conditions like diabetes and cancer were also quickly identified as being at increased risk from COVID-19. And men seem to be more likely to become seriously ill or die with the disease than women.  

But analysis of data from the COVID Symptom Study app, along with studies from other research groups, has suggested that people who are very overweight (obese) are also at greater risk of developing severe symptoms and ending up in hospital with COVID-19, even if they are young.

Nearly 40% of adults in the US are classified as obese, potentially putting a large chunk of the population at increased risk during the coronavirus pandemic. At the same time, it’s vital not to further stigmatise people who are overweight or obese, who are already likely to suffer from poorer healthcare due to medical bias about their weight.

We take a look at the evidence so far linking obesity and COVID-19, why gathering data to identify those at risk from coronavirus is so important, and what everyone can do to protect their health at this time.‍

What do we know about obesity and COVID-19 so far?‍

Medical professionals suspect that obese people may be at increased risk from COVID-19, but so far, there hasn't been much research on the subject. Here is what we know so far:

• Studies from China showed that people who developed critical COVID-19 and died had a higher BMI on average than people who had more moderate cases of the virus and recovered. 
• Research from the US has shown that younger patients admitted to hospital are more likely to be obese.
• Of the people admitted to ICU with COVID-19 in the UK, 73% were overweight or obese.
• Research in the UK has suggested that people who are obese are 33% more likely to die with COVID-19.
  

We have been tracking the effects of COVID-19 in over 2.6 million people using our COVID symptom study app, asking participants questions about their height, weight and medical conditions, and asking them to log their health on a daily basis.

We found that people who were obese were around 20 percent more likely to be hospitalized with COVID-19 symptoms compared with people with lower body mass index (BMI), and also more likely to need respiratory support such as ventilation. This was true across all the age groups we looked at, including younger people.‍

Obesity affects health and immunity‍

Obesity not only increases the chances of developing chronic health problems like heart disease and diabetes, but it also increases the risk of infections. 

Research has shown that people who are obese often have impaired immune responses, meaning it is easier for germs like viruses and bacteria to invade the body and set up an infection. Being obese also makes severe complications from infections more likely, including acute respiratory distress syndrome or ARDS (one of the most serious symptoms of COVID-19), thanks in part to higher oxygen demands from a larger body. 

Studies have shown that people who are obese are also more likely to catch seasonal flu, suffer for longer, are more at risk from severe outcomes, and more likely to pass the infection on to others. ‍

How many people are at risk?‍

The revelation that being very overweight increases the risks from COVID-19 is particularly concerning when you consider that nearly a third of adults in the UK are classified as obese - adding up to around 13 million people - with a further 35 percent who are overweight. 

While the studies so far clearly show that obesity does increase the risk from COVID-19, they don’t explain how this works. And given the complex relationship between weight, health and many other social factors, the effect is likely to be the result of the combined interaction between physical, social, and environmental factors. 

Being overweight or obese increases the risk of a number of underlying health conditions that make people more vulnerable to the effects of coronavirus, including diabetes and heart disease. ‍

Race and social class also come into the mix. And weight stigma from doctors and other healthcare providers may also prevent people from getting the care that they need, leading to more serious problems further down the line.‍

How to stay healthy during the pandemic if you are overweight‍

Although the NHS and CDC list obesity as a risk factor for COVID-19, there is little specific advice for overweight individuals about how to protect themselves from the disease. However, it’s probably a good idea for everyone to focus on supporting our health and immunity, at any size. 

Here are our tips:

1. Cut your chances of catching coronavirus by following your local social distancing and hygiene guidelines, including regular hand washing and avoiding large gatherings
2. Maintain or move towards a healthy weight by following an eating plan that’s right for you (see our nutrition blog for help with that one) 
3. Nourish your body with plenty of fruit and vegetables to support your immune system
4. Do physical activities that you enjoy on a regular basis
5. Look after your mental health as well as your body
6. Get a flu shot ahead of the flu season this year‍

Why is it important to study who is at risk from COVID-19?‍

Knowing about the links between coronavirus and obesity isn’t about blaming or fat-shaming: it’s about making sure that people who are at risk can be protected and get the care that they need if they get sick. 

That goes for everyone in the population, whoever they are. It’s a principle we call health equity, which means giving every individual what they truly need to reach their optimal health.

As well as investigating the impact of health-related risk factors such as obesity, our COVID Symptom Study app is also looking at the influence of ethnicity, geography, hormones and more. 

All this data is helping to map the spread of coronavirus across the country, understand the key symptoms of COVID-19 and how it progresses, and provide vital information to healthcare providers and public health bodies to direct resources and testing to where they’re needed the most. ‍

Summary

• We need to know who is at risk from coronavirus so we can protect the right people and be prepared if they get sick.
• Using our COVID symptom study data, we have identified obesity as a risk factor for hospitalization with COVID-19.
• We don’t fully understand the link between coronavirus and obesity, and there are many factors involved
• We can all take steps to support our health and immunity at this time, at any size
  

We are continuing our work with the COVID symptom study to fully understand who is at risk, how we can protect them, and be prepared if they get sick. Check out http://covid.joinzoe.com/us to find out more.

Find out more:

• Coronavirus: Does being overweight or obese affect how ill people get? – BBC News 
• Evidence obesity is a risk factor for serious illness with coronavirus is mounting – even if you’re young – The Conversation 
• Coronavirus linked to greater risk of life-threatening infection in people with obesity – The Conversation
• Disparities in the risk and outcomes of COVID-19 – Public Health England 
• Key predictors of attending hospital with COVID19: An association study from the COVID Symptom Tracker App in 2,618,948 individuals – MedRxiv
• Obesity and the Immune System – OAC 
• Influenza and obesity: its odd relationship and the lessons for COVID-19 pandemic – Nature Public Health Emergency Collection
• Obesity in Patients Younger Than 60 Years Is a Risk Factor for COVID-19 Hospital Admission – Clinical Infectious Diseases 
• Features of 16,749 hospitalised UK patients with COVID-19 using the ISARIC WHO Clinical Characterisation Protocol – MedRxiv
• Who's at higher risk from coronavirus – NHS 

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