Main Image


It has been a pretty hot topic since the start of the pandemic; What are the comorbidities of Covid-19? The further we go into this pandemic, the more we know about who is at risk. More importantly, we know how we can help alleviate that risk. However, the warning signs have been there before when it comes to our general health. All of the research is showing the escalating risk of hospitalisations and deaths from Covid-19 to those overweight or obese. So why is the topic still the elephant in the room? Rather than honest and open conversations about the risks of living with obesity.

There is, and always has been, a huge stigma around the words ‘fat’, ‘overweight’ and ‘obese’. We are in an industry that is trying to tackle obesity and unhealthy lifestyles, and yet even writing this blog outlining the risks of obesity in the current pandemic, we run the risk of it being taken the wrong way.

This just outlines the uphill battle we face as a society in tackling obesity.

The purpose of this blog is to not only highlight the risk. It is also to understand why being overweight or obese increases the risk of hospitalisation and death from Covid-19. If we truly want to help and get our message across, there’s no point highlighting it without helping to understand why this occurs. So, if you think being obese is just about how someone looks, it is far from that.

We don’t judge people for how they look on the outside. Our concern is what is happening inside the body, where the real damage is occurring. 


NHS statistics in 2018 showed that over a quarter of UK adults are obese and 63% are overweight or obese. This number has doubled since 1993. This has resulted in obesity costing the UK £6.1 billion per year, and £27 billion as a wider society. This is taking into account the further health risks of obesity on issues like type 2 diabetes, hypertension and certain cancers.

In 2019, there were 876,000 hospital admissions where obesity was recorded as the primary or secondary diagnosis. That is 2,400 hospital admissions per day.

The most concerning numbers are the rise in child obesity. According to Public Health England 2015 statistics, 28% of children between ages 2-15 are either overweight or obese. Even children aged 4 to 5, nearly 10% are obese and another 12.8% are overweight.

The amount the UK spend is astronomical. How they spend that money could be criticised, as strategies time and time again have been delivered to almost zero effect.

However, the general changes in our lifestyles since 1993 that have contributed to obesity levels doubling should be on us. 




Firstly, let’s start with how obesity is measured in most scientific studies. The simplest way of measuring is through BMI (body mass index). A calculation of a persons weight compared to height is how BMI measurements are taken. Every PT reading this is rolling their eyes at the mention of BMI. It is a measurement that has received a lot of criticism. Mainly because it does not take into account what amount of our body mass is fat, and what is our skeletal system (muscle and bone).

This is where the measurement can certainly be improved. As the population of people lifting weights and sports people may have a relatively low amount of body fat with higher muscle mass, but still be classed as overweight on a BMI scale. This can be improved slightly by taking a waist measurement. The NHS recommend a weight loss strategy if your waist is 94cm+ for men and 80cm+ for women. So, if your BMI classes you as overweight but you have a good amount of muscle mass and your waist is below these numbers, then there is a good chance you are not overweight.

Despite this, BMI is a useful measurement for the general population. As it is so simple to measure and very non-invasive. This makes it relevant to research studies that require hundreds or even thousands of participants, particularly if the cohort are mainly the general population. Below are the classifications of BMI from underweight to extremely obese.


The effect of being overweight or obese is a health issue regardless of Covid-19. The metabolic stress it puts on the body puts us at risk of many illnesses and diseases. We store excess fat in the wrong places, mainly around key organs such as the liver and lungs. This impairs their function and makes them have to work harder. The extra fat in skeletal muscle and liver can disturb our metabolic function by increasing insulin levels in the blood. This reduces our ability to control those insulin levels, hence why it makes us more at risk of diabetes.

The information we have on Covid-19 is only going to be as strong as it can be after 12 months. We will start with what we have learnt from other outbreaks such as SARS-CoV from 2002 and Swine Flu (H1N1) from 2009. This shows that the warning signs have been here for a long time.

Studies on Swine Flu showed that both the amount of virus shed within the body and the duration of virus shed increased in obese individuals compared to lean individuals (graph below).

An American study in 2009 revealed that in California, 51% of all adult Swine Flu cases were in those with obesity. This resulted in 61% of all deaths occurring in obese individuals.

The main mechanisms behind why overweight and obese individuals may suffer more from these types of viruses are mainly based around the bodies inflammatory state. This can inhibit the immune systems response to the virus. We will go into the mechanisms in a little more detail later.


Now for the main event. So far, we have found the most common comorbidities associated with severe symptoms and mortality to be older ages (65+), obesity, hypertension, diabetes and various cardiovascular diseases. Out of these, I think it’s safe to say that obesity is the one that we can do something about. Especially as obesity also makes someone more susceptible to hypertension, diabetes and many CV diseases.

In a study on the first wave of the pandemic (see graph below), it showed that of the critically ill patients with Covid-19, over 70% of those patients were either overweight or obese (BMI >25). This was a bigger contributor than age (being 50+). 

Another Spanish study on the traits of patients admitted to ICU due to Covid-19, found obesity to be the most common comorbidity out of everything (48% of patients).

A systematic review of 75 different studies on Covid-19 was completed last year and the numbers showed the substantial risk for individuals with obesity:

  • 46% more likely to contract Covid-19
  • 113% more likely to be hospitalised from Covid-19
  • 74% more likely to be admitted to ICU from Covid-19
  • 48% more likely to die from Covid-19

The below illustration from a Southern California study also shows the increasing risk ratio associated to a higher BMI. Patients with a BMI measurement of 40-44 had a risk ratio of 2.68 and patients with a measurement greater than 45 had a risk ratio of 4.18. This means they were over 4 times more at risk of death compared to someone with a BMI of 18.5-24. This study also showed that obesity was a big risk factor even for younger adults. Particularly in men under the age of 60, the risk increased significantly and was the most common comorbidity. 


The fact that obesity is a risk factor for contracting Covid-19 and mortality means it can no longer be ignored. It is not about fat shaming; it is about understanding that obesity has far more implications on a persons health than how they look. The main point of this blog is for you to understand why there is an added risk, and what having excess fat can do to your immune system both short-term and long-term.

Firstly, being obese increases our risk of the majority of other comorbidities; Type 2 diabetes, hypertension, cardiovascular disease and heart disease. That increases the risk alone.

Obesity is a metabolic disease. Hormones and nutrients are not controlled appropriately. Hormones like leptin are increased and hyperglycaemia (excess blood glucose) occurs. Both of which have been shown to increase Covid-19 mortality. This lack of blood glucose control can impair immune cell function and blunt the response to a virus or disease. 

We also discussed previously that virus is shed for longer and more intense in obese individuals. The mechanisms by which excess fat affects our immune system, however, is mainly due to inflammation and ‘cytokine storms’.

Interferons (IFNs) are protein molecules and are a type of cytokine. We have anti-viral interferons in our body protecting our immune system. They quite literally “interfere” with viruses in the body and help to stop them taking over our immune cells. One of the reasons obese individuals have a decreased immune response is because they have reduced numbers of these IFN’s protecting their immune system. This coupled with them have an increased number of cytokines like IL-6, which are a pro-inflammatory cytokine (and therefore increase inflammation in cells), put them at a much higher risk of severe infection.

This increase in inflammation is happening in the lungs in particular, especially during infection of a respiratory disease. Hence why obesity is linked to a reduced lung function and chronic obstructive pulmonary disease (COPD).

Cytokine storms are an uncontrolled inflammatory reaction of the immune system to virus or infection. When a person is carrying excess fat, IL-6 cytokines and C-reactive protein levels are increased. These are both signs of inflammation in the body and cells and are very prominent in cytokine storms. If an immune system reacts to infection with these uncontrollable cytokine storms, the response to the virus is elevated and significantly more severe. With obese individuals having higher levels of both of these cytokines circulating, there is more chance of them creating a cytokine storm when they have been infected by a virus. This puts them in danger of hospitalisation and mortality.

All of this coupled with excess fat tissue can put a huge strain on the immune system and cardiovascular system, in particular. Just increasing the amount of fat stored around essential organs, such as lungs, can put the organs under increasing stress. If they are struggling to function already, the increased fat putting pressure on them can exacerbate the issue.


Unfortunately, given the current situation and obesity levels rising year on year, there is no easy way out of this. We have already gone through the crippling costs on the NHS and the number of hospital visits per year due to obesity (876,000 in case you had forgotten).

Over the coming months and possibly years, we will see obesity levels worsen before there’s any chance of improving.

During the first UK lockdown of 2020, a study on 1.6 million people showed the following outcomes.

  • 29% of people increased in weight
  • 34% decreased the amount of exercise they did
  • 35% increased their amount of snacking
  • 19% were eating less healthy than before
  • 27% were drinking more alcohol
  • 29% of smokers were smoking more
  • 42% admitted to being worried about their physical and mental health

That was in a lockdown in spring/summer, I would take a guess to say these numbers have gotten worse in a winter lockdown. These changes in habits are tough to get out of if you have been doing them for months at a time. Pair that with the fact that people have consumed more processed foods during the lockdown too, and it makes a very difficult scenario to just simply snap out of it when restrictions are lifted. Many people have lost jobs and even more have had their earnings reduced. Unfortunately, this lower income is associated with a lower quality of food supply. Partly because these ultra-processed alternatives are cheaper and have a longer shelf life.

The other knock-on effect of obesity is the potential for the Covid-19 vaccines to be less effective. In influenza vaccines this is certainly the case, but hopefully Covid-19 vaccines can still be effective. The main mechanism for why they may not be as effective in obese individuals is because T cell production in response to infection is the key to the vaccines being effective. Unfortunately, T cell responses have been shown to be impaired in obese individuals.


Again, what’s the point in writing this if we didn’t want to try and help in some way. What can we do right now to help this situation, protect our own health, our family’s health and of course our NHS?

Other than the obvious “we need to lose weight”, there are things we can start doing. But it all starts with taking responsibility for our own health.


I would love to see more research done on this side of things, but there a few studies out there. One study showed that in men who were of normal BMI, those that had a low level of CRF had a 163% higher mortality risk than men who were fit.

Other evidence points at CRF improving the inflammatory response of our immune system to Covid-19 infection, even in obese individuals. Exercise and CRF have a positive effect on lung function for starters and help to lower risk of respiratory infections. Exercise can lower chronic inflammation, and also elicit an anti-inflammatory response in the body that combats the usual pro-inflammatory markers you see with infections and viruses.

Therefore, just increasing our fitness levels can help to put our body and immune system in a better state to fight infections and viruses.


We discussed this in a blog right at the start of the pandemic. There is some really promising evidence showing that higher levels of vitamin D in our bodies are associated with a greater protection against Covid-19. Having insufficient levels increased the risk of hospitalisation and mortality greatly. Why we are not doing more to encourage vitamin D intake off the back of this is beyond me. Especially with the evidence of vitamin D improving immune system function in general, but that’s another subject entirely. If you are interested in learning more about this, have a read of our previous vitamin D blog.

One thing is for sure, having sufficient levels of vitamin D along with living an active lifestyle and a good diet will put you in a far better position to fight off the majority of illnesses and viruses. Our digestive system and gut are closely linked to both our brain and immune system. The better we take care of our nutrition, the better our nutrition takes care of our brain and immune system.


This may be slightly controversial to discuss. We touched on it in the introduction but trying to mask this comorbidity is a very dangerous thing to do. We need to be completely open and honest about the people that are risk and encourage them to do something about it. Otherwise, this issue will only worsen.

Mainstream media are partly the culprits here, too. We often see stories of younger adults suffering in hospital with Covid-19, and the headlines will be that the patient has no comorbidities. Unfortunately, when you see the photo of the individual, more often than not that person is obese or at least overweight. This isn’t helping anyone and in fact feeds the problem further.

However, encouragement is what is needed here, not just being blunt and telling people they are at risk. Helping each other to understand that it is more than just how they look, it’s the unbearable pressure it is putting on their body and organs. Despite it being tough to lose a significant amount of weight, it is very possible when people have the right support, and truly want to do something about it.


Now for what we as a health and fitness industry can do. I’m sure this probably isn’t what you’re expecting to hear. We can shout from the rooftops about how gyms help to keep people healthy, both physically and mentally. That is absolutely true, and we are the biggest advocates of that, so please bear with me why I think we need to do more.

There are roughly 10 million people in the UK using gyms, which is around 15% of the population. 63% of the population are either overweight or obese currently, which is about 42 million people. The gym industry has boomed over the last 30 years, yet obesity levels have also soared in that time.

The easiest thing for gyms to do is to get young and fit people to attend. The emergence of budget gyms has made getting fit more affordable for everyone. However, the only ones benefitting from this gym model are generally already healthy and not overweight, they also have an idea of what to do when it comes to exercise and nutrition.

Gyms will always market their product to look cool and modern, to attract that demographic. The people that need gyms the most aren’t even in their thoughts. This is why beginners and overweight individuals feel too intimidated to even start. They feel like they don’t belong there and won’t get any support whatsoever.

Overweight or obese individuals are the ones that need to be coached through the whole process to make positive long-term changes to their health. Budget gyms and health clubs do not do that.

This is just creating a larger gulf between unhealthy, obese individuals and the regular gym-goers.

For this reason, I truly believe our industry is doing the general public a disservice. This could possibly be a reason why the government have dismissed us as part of the solution to this pandemic. All of the data is there to show why staying fit, healthy and not overweight can help to fight Covid-19 and save the NHS billions of pounds per year.

Even before the pandemic, the fitness industry has never been an integral part of a government scheme to promote keeping fit and healthy. There is a lack of trust there that is deeply ingrained.

In order to really make a difference, our industry needs to change for the better. There absolutely is a place for these types of gyms to give people cheap access to great facilities. But are they the right service for the 42 million or so people who are overweight or obese and most likely don’t like going to the gym?

Quality coaching is the answer. Supportive coaches that educate rather than just make clients sweat for an hour. Coaches that help people that don’t necessary like training, or don’t know where to start.

Health and fitness is about living the lifestyle, not about being the strongest or the fastest. It is our job to help people make these positive lifestyle changes, that they can then pass onto their children and improve the next generations health as well as their own.

We also need to make a welcoming environment to all walks of life. Something I am most proud of at GWD Performance is creating that environment to help people to excel, no matter how inexperienced, unfit or struggling mentally. Everyone is running their own race with their own obstacles.

The people that need the fitness industry the most, are the ones least likely to use gyms. We need to do everything we can to make it a positive experience for them. 

We are on a mission to help those that need it most. It is the health and fitness industry after all, it’s about time we stepped up the health side of it and made a difference.