Covid-19 Mortality Outcome

Obesity and Covid-19: the challenge is growing

That obesity is a risk factor for doing badly following infection with Covid-19 is well known.  Recent data has given some more precise estimates of the risks and also what the explanations might be. More relevant is the concern that health services should be doing more and, as I will explain at the end of this post, is that health services have not learned the lessons from Hurricane Katrina (and on which I made my first public contribution this week to this debate!)

How is obesity defined?

  • I am sure this is well known to readers of this blog!
  • There are accepted cut offs based on body mass index (BMI) which is calculated from weight (measured in kg) divided by height squared measured (in metres).
  • The following thresholds are used (which I have translated into the nearest stone equivalent) for a women of average height 5ft 3 inches and a man 5 ft 9 inches.
  • From this  a male of this height with a weight over 14 stone is considered obese

Waist hip ratio

  • Apart from BMI, epidemiologists also measure the ratio of waist to hip circumference (WHR)
  • The waist should be smaller than the hips but the cut off for normality varies between the genders-women have smaller waists.  
  • Excess weight around the waist is consider as ‘central obesity’ and is more hazardous for health
  • A report in the British Medical Journal this September reviewed all the major research and found importantly that a central obesity is a predictor of dying prematurely from all causes after allowing for BMI
  • In other words, both body weight and body shape are important   

Obesity and Covid-19: risk of becoming infected

  • The UK Biobank Study published this month data from a large population survey of over 500,000 people who had had different measures of obesity and linked these data to the national laboratory Covid-19 test database
  • The results show a 60% greater risk of catching infection in obese people compared to people of normal weight.
  • They found a similar increase in risk looking at waist circumference 
  • What was even more interesting was that the risk of Covid-19 from obesity was greater in people from black and other ethnic minorities (BME)
    • As an example an obese (BMI>30) person from the BME community will have twice the risk of being CoVid-19 positive than a white person with the same BMI
    • This is not due to the rate of infection in those from  BME groups being higher anyway: the rate of infection in non-obese (BMI<25) was the same in both white and BME groups

Obesity and risk of severe disease

  • On top of an increased risk of getting the infection there are loads of studies showing that people who are obese have a greater chance of being admitted to hospital,  and once admitted ending up in an intensive care unit
  • Below is the up to data information of Covid-19 admissions to all the ICU’s in the UK
  • As shown compared with the background population, more  obese and severe obese patients are admitted to intensive care 
  • Once admitted obese and severe obese patients are at a substantial increased risk of dying. A recent summary of several studies showed that mortality rates approached 70% in the most obese patients admitted to ICU’s
  • Having an unhealthy waist hip ratio, adds to those risks for example leading to a doubling of  the chances of needing hospitalisation

Why does obesity make Covid-19 worse?

There are many theories but these include a mixture of plausible explanations

  • Obese people have a constant low grade of inflammation in their bodies even when they are well, but this gets worse when they have an infection
  • The virus stays longer in the organs such as the lungs as the immune system struggles to get rid of the virus 
  • Obese people make more of a protein called ACE2 which stays on the surface of lung cells and it is that protein which is thought to be what the spikey bit of the Covid-19 virus sticks to
  • Obese people have fewer of the healthy bacteria, we all have, hanging around in their guts and lungs, and this interferes with our natural immunity 
  • Lung capacity is reduced, the more obese people cannot expand their lungs so well 
  • It can be more technically challenging to treat obese people in ICU’s
  • Obese people have greater problems with  diabetes and high blood pressure 

Why am I covering this topic now?

  • The data are overwhelming that obesity, and its disease partners diabetes and high blood pressure, increase the risk of Covid-19, of being admitted to hospital with Covid-19, of ending up in intensive care and of dying
  • We are also faced, as a result of the pressure of managing acute Covid-19,  with a major reduction in routine health care especially in primary care and the putting on hold the preventive health  care that identifies those who have these health issues and actively manages them.
  • Following Hurricane Katrina, general health deteriorated in the population because of diversion of health care to manage the acute problems
  • These recent data from a global survey of health care professionals highlight the great impact of Covid-19 on health care in general, and these easily managed problems in particular
  • The point is that unless there is a return to active prevention programmes, health screening and regular primary care contacts, obesity and its consequences will go unchecked making the outcomes of Covid-19 much worse.
  • I made these points at a workshop I attended this week!
  • Hopefully someone will listen!

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3 replies on “Obesity and Covid-19: the challenge is growing”

Thanks Alan, unfortunately the graph for Impact of COVID above is very blurred. Maybe it is just on my tablet?


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