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Obesity and COVID-19


Serious disease is affecting around 20% of persons with COVID-19, and 5% develop complications. But a question that is still under debate is whether obesity is a risk factor for more serious disease or complications.

For those of you uncertain about the terminology:

  • Coronavirus: the common name for a family of viruses, some of which can infect humans
  • SARS-CoV-2: a strain of coronavirus that was first detected in China late in 2019 and that is the cause of the current pandemic
  • COVID-19: the disease caused by infection with SARS-CoV-2

Obesity is now considered by some sources to be a risk factor for more serious symptoms of COVID-19. This is probably because the chronic conditions that have been shown to make COVID-19 worse are more common in obesity: heart disease, diabetes, cancer, and alterations of the immune system.

Obesity also increases the risk because medical procedures, such as intubation for assisted ventilation, are more difficult. Ventilators must work at high pressure due to the weight of the chest wall; this can harm the lung tissues. Prolonged bed rest has a higher risk of causing skin problems if you are obese, and it can be more difficult for the body to cope lying flat for long periods.

Finally, obesity is associated with a chronic inflammatory state in the fat tissue. This keeps the immune system on high alert, making it more likely to overreact to triggers like the coronavirus. Should this happen, the immune system can damage the lungs, interfering with respiratory function. This is one of the reasons why some COVID-19 patients require intensive care.

Persons with weight issues should therefore consider themselves to be in the at-risk groups for more serious disease. They should be stricter with their isolation procedures and hand hygiene, and anyone who may be helping people in this situation should show equal respect for isolation measures. Losing weight should be done under strict control; fad diets will weaken your immune system and could therefore have a negative health effect if you become infected. See the end of this document for some additional comments on diet and weight loss.

If you would like a more detailed explanation, please read on

Risk factors for more severe symptoms of COVID-19

The conditions that that have been identified as risk factors for more severe disease due to SARS-CoV-2 infection (COVID-19) are the following:

  • Over 60 years of age
  • Pregnancy

And the following diseases:

  • Cardiovascular disease and high blood pressure
  • Diabetes
  • Chronic lung disease
  • Cancer
  • Conditions that affect the immune response

However, scientific societies such as The Obesity Society and the World Obesity Federation now consider that obesity puts patients at greater risk. The main reasons for this are the following:

  • The diseases listed above are more common in overweight and obesity
  • If more serious disease occurs, nursing care is more difficult
  • Medical procedures such as intubation and ventilation can be more complex

Parallels are being drawn with the risk of complications during influenza infection. The Center for Disease Control of the United States recognised obesity as a risk factor for complications during the 2009 flu pandemic.

Further evidence of doctors’ concern comes from the treatment protocols used by hospitals, which are being regularly updated at the moment. For example, the YNHHS (a US regional health system with links to Yale University) now includes body mass index among the criteria for earlier specific therapy in its treatment algorithm for COVID-19.

It now appears clear, therefore, that we must take special care of persons with obesity, ensuring adequate isolation and being even more vigilant with hygiene measures. However, let us not forget that social isolation is a central factor in the stigma still felt by many obese patients; the stricter isolation needed during the pandemic could increase this psychological stress.

Health professionals and the public in general must be aware of these issues and must take them into account as we face special situations during this pandemic.

Obesity and the immune system

Obesity and metabolic syndrome (a group of signs and symptoms that indicates metabolic imbalance and an increased risk of chronic disease) are known to alter immune status, provoking

  • Adipose (fat) tissue inflammation
  • Changes in leukocyte (white blood cell) counts

These changes are responsible for impaired immunity in obesity and are considered to be the link between obesity and chronic disease.

Pulmonary complications of COVID-19

Those complications of COVID-19 that affect the lungs are the principal cause of death in this disease. Pulmonary complications are of different types: pneumonia due to the virus; secondary bacterial pneumonia; and cytokine storm.

Viral pneumonia due to SARS-CoV-2 is particularly severe as it tends to affect the whole of both lungs, rather than just a segment (bacterial pneumonia usually only affects a part of one of the lungs). As yet, we have no specific treatment, and can only use supportive measures, such as assisted ventilation, to give the body’s immune system time to overcome the disease.

Secondary bacterial pneumonia is when bacteria infect an area of a lung previously damaged by another infection (in this case, SARS-CoV-2). This requires antibiotic treatment.

Cytokine storm, otherwise known as macrophage activation syndrome, is a hyperinflammatory reaction. This is a hugely exaggerated immune response that can be triggered by the SARS-CoV-2 virus. In this situation, the body’s defence systems designed to fight infection cause damage to the body’s own tissues. Lung damage is a common complication of a cytokine storm and can lead to acute respiratory distress requiring treatment in intensive care.

Obesity and cytokine storm

In obesity, there is a state of chronic low-grade inflammation caused by changes in the adipose tissue. This chronic inflammation depends in part on T lymphocytes and macrophages, which just happen to be principal actors in the cytokine storm. It would appear that obesity could therefore make an individual more susceptible to this increased immune reaction to infectious organisms, increasing the risk of developing respiratory complications.

What to do about it

The first and most immediately important thing to do is eat a balanced healthy diet. My recommendation is to follow a Mediterranean-style diet, based mainly on plant foods, including a wide range of coloured vegetables (the colours come from different molecules such as antioxidants, vitamins, etc., which support the body systems that fight infection). For people who eat meat and fish: limit red meat intake, preferably eating fish and white meat (chicken, turkey); fish should be eaten 2 or 3 times a week, with oily fish (sardines, mackerel, salmon…) making up 1 or 2 of those servings.

Carbohydrates: always use the healthy carbs – i.e. unrefined. Wholegrain products (especially wholegrain wheat products, oats, brown rice, quinoa…), pulses and legumes, seeds such as chia and pumpkin, nuts. Be careful not to overdo it with seeds and nuts as they have a lot of calories because of the fats they contain (though these are healthy fats, in general). When using prepared foods such as bread or pasta, look for wholegrain/wholemeal varieties. And remember there are now interesting pasta substitutes made of lentil, pea or other unrefined flours.

Processed foods: Avoid fast food. These foods are designed to increase our appetite by activating our reward centres in the brain. They typically do this by including energy-dense ingredients, a ratio of fats to carbs known to be more pleasurable to the palate (1 fat:2 carb), refined carbs with a high fructose content to make the taste sweeter, and a high salt content. The fats are usually the unhealthy ones (particularly trans fats), used to achieve the desired consistency. Most products have a low fibre content and a very high number of “chemical” ingredients to extend the expiry date. Both of these factors are going to have a negative effect on the gut bacteria; this gut microbiome is now known to play a very important role in health, particularly through its effect on immune regulation. In summary, fast foods have a deleterious effect on health. Most processed foods are similar to fast foods from the health point of view, as processing typically removes certain key ingredients and adds chemicals.

Consider losing weight. As already mentioned, overweight and obesity are associated with an inflammatory state. Weight loss will reduce this inflammation. This can have very positive effects on the changes that predispose to chronic disease, such as insulin resistance. But please be aware that not all diets are the same. Fad diets that do not provide the micronutrients needed by the body are detrimental to health. Talk to a health professional to find a healthy weight-management programme that works for you.