The fat of the land: Obesity in a time of Covid-19

This is a personal as well as a scientific blog, and as such is being posted on both my websites. My BMI currently puts me into the obese category. I have often said that I don't have an issue with food – I just like it too much. I may be fit and obese, running half marathons, but I can still be damaging my joints and my heart, and risking type 2 diabetes. ​

​But now, in the time of Covid-19, obesity puts me at a higher risk than the rest of the population should I become infected.

How big is the risk?
In patients under 60, obesity is a risk factor for hospital admission. In a US study, patients with a BMI of 30-34 were around twice as likely to be admitted to acute or critical care, compared with those with a BMI of less than 30. In patients with a BMI of over 35, the likelihood of being admitted to acute or critical care rose by 2.2-fold and 3.6-fold, respectively. Higher numbers of obese patients require invasive mechanical ventilation.

The OpenSAFELY collaborative carried out a review of electronic medical records of patients in England. According to the results, having a BMI of between 30 and 35 (obese) increases the risk of hospital death by 1.3-fold. This climbs to 1.6-fold for a BMI of 35-40,  and a BMI of greater than 40 (morbidly obese) more than doubles the risk of death (2.3-fold). Because the science is moving so quickly, this preprint has not yet been finalised or assessed by experts (peer-reviewed).

The science behind the difference
Being overweight generally makes it harder to breathe, and is known to be a risk factor in respiratory diseases such as asthma, sleep apnoea, acute lung injury and acute respiratory distress syndrome.

There are a number of theories behind the increased risk of more severe illness and death related to Covid-19 in people who are obese:

• Obesity is often linked with type 2 diabetes and other metabolic disorders, which are risk factors in Covid-19 infection.
• Excess fat in the body can cause low-grade chronic systemic inflammation, worsening respiratory diseases.
• The fatty tissue may act as a viral reservoir.
• Excess fat is linked with overactivation of the complement system, part of the immune system. This could increase the risk of a cytokine storm, an uncontrolled and dangerous immune system overreaction.

It is also much harder to intubate someone who is obese, and ventilation is more difficult as the lungs are smaller compared with the size of the body and oxygen demand is higher.
Looking at the futureMy weight has gone up and down over the years. My biggest gains were in my thirties, and I lost three stone before I got married in 2009, giving me a BMI of 24. During my marriage and following bereavement, the weight went right back on.
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But it's not just me. The most recent Health Survey for England (2018) found that 67% of men, 60% of women and 28% of children were overweight or obese. As SARS-CoV-2, the virus that causes Covid-19, is likely to stick around for some time to come, tackling obesity is going to be important.

As part of COUCH Health's mission to improve 1 million lives by 2022, I have pledged to lose weight as part of a challenge alongside my friend and medcomms colleague, Ash Rishi. It has been up and down during the lockdown, but I'm going to try again, driven by the excess risk of Covid-19, using the evidence-based and NHS-backed Low Carb Program. ​

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