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Obesity and Covid-19: why are obese people more likely to suffer Covid complications?


Obesity remains one of the biggest health challenges in the UK. Around 68% of the adults are either overweight and obese and about a third of our children are overweight or obese. While obesity is linked to various health problems, including heart and circulatory diseases, it also appears that being overweight or obese increases your risk of dying from Covid-19. The more overweight you are, the greater your risk, according to official statistics.

While research is still being conducted on exactly why this is the case, there can be no doubt about the facts. A study published in April 2020 examining 16,749 UK patients in hospital with Covid-19 found that obesity was linked to a higher risk of dying (around a 37% increase in risk of death). That study took into account factors such as age, sex and other health issues. People with obesity were also more likely to be hospitalised and have a serious illness with Covid-19. More people with obesity and diabetes were admitted to an intensive care unit and were put on a ventilator compared to the general population.

So, why might it be the case that people with obesity are experiencing more complications from Covid-19 infection? Dr Chinnadorai Rajeswaran. Consultant Physician, explores the top five reasons:

  1. High risk of developing blood clots

The blood of people who are obese has an increased tendency to clot. Blood clots can lead to life-threatening conditions like pulmonary embolism (clots in the lungs) or deep vein thrombosis (clots in the legs). The likelihood of a blood clot is further increased when an infection occurs.

People who were admitted to intensive care units with Covid-19 were found to have a sticky blood, and were found to have tiny clots scattered in their lungs. Normally, the cells that line the blood vessels prevent formation of blood clots. However, in Covid-19 infection, the endothelial cells that line the blood vessels are damaged triggering clot formation. This is why, when people get admitted with infection, they are offered blood thinning injections in the hospital.

  1. Poor lung reserve

A study led by the Barcelona Institute for Global Health analysed the effect of weight changes on respiratory health over a 20-year period. They found that people with a high Body Mass Index (BMI) experienced rapid decline in lung function when they gained weight.

They found that increased fat in the abdomen and chest limits the lung from expanding during inspiration. Fat or adipose tissue produces inflammatory substances which damages the lung tissue and narrows the airways within the lungs.

However, the good news is that the negative effects on the lungs due to obesity can be reversed through weight loss.

  1. Associated co-morbid conditions like type 2 diabetes and high blood pressure

People with obesity are more prone to developing type 2 diabetes, hypertension or high blood pressure and heart disease. These medical conditions along with obesity have a serious impact on the functioning of the heart and lung.

When people with obesity are infected with Covid-19, there is an added stress to the body and hence many suffer serious complications such as pneumonia. Sadly, more people with type 2 diabetes and hypertension have died from Covid-19 than the general population.

Weight loss helps improve blood glucose control, reduces blood pressure and the risk of developing heart disease.

  1. Ineffective immune response to Covid-19

Obesity causes a chronic, low-grade activation of some parts of the immune system. When someone with this pre-existing condition is faced with an infection, the immune system goes into overdrive. Therefore, the immune system in obese people is not able to fight infection effectively.

Several studies have shown that the excess fat tissue mass in people with obesity directly contributes to the immunological problems in obesity. It is well known that the enlarged fat cells in people with obesity exaggerates the immune response and renders immunity against the virus ineffective.

The key immune cell called “T- cells” do not function as well in people with obesity.

Weight loss helps improve the functioning of fat cells and thereby improves immunity and the ability to fight against viral infections.

  1. Exaggerated inflammatory response

When we injure ourselves, that part of the body is swollen and becomes red. This is called inflammation and is due to certain chemicals produced by the body in response to injury.

Obesity is an inflammatory condition. Fat tissue produces lots of inflammatory chemicals. When the body is subjected to infection like a viral or bacterial infection it results in inflammation of the lungs. In obese people who have pre-existing inflammation, the response is multiplied, leading to serious damage to the lungs and other organs. One of the main problems with Covid-19 is due to this exaggerated inflammation.

Weight loss leads to reduction in fat tissue and resulting in reduced inflammation.

As mentioned above obesity is a chronic, inflammatory condition which leads to several medical conditions including type 2 diabetes, hypertension, fatty liver, liver cirrhosis, hypertension, arthritis, back pain, depression and some types of cancer. In addition, we know that people with obesity are more likely to have complications with Covid-19.

Most people know that in order to lose weight they should eat a healthy, balanced diet and increase their level of exercise. Of course, diet and exercise combined are one of the most common ways to lose weight – and acquiring or maintaining a healthy lifestyle is fundamental. Having said this, diet and exercise can often be temporary options for weight loss, and unlikely to offer the long-term results and benefits that surgical treatments can provide.

For some people, diet and exercise have no impact and they are unable to lose excess weight. This is because there are a number of factors that affect weight gain. Fad diets and restrictive diets can lead to weight loss but are usually followed by weight regain.

It is important to understand the underlying reason for weight gain and address them. Only a personalised approach will help in losing weight and sustaining the weight they have lost in the long term.

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