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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.




Vitamin D, the sunshine vitamin. It has been nicknamed that because the main source of it is sunlight. It’s synthesised in the skin in the response to exposure to UVB rays. It is also found in foods, but on a lesser scale. It is prominent in fatty fish, eggs, cod liver oil, and is also in a lot more items such as milk when the product is fortified.

Vitamin D has been in the news a lot recently. A few recent studies have shown a significant correlation between vitamin D deficiency in Covid-19 mortalities. Some news story headlines I’ve seen;

“Could Vitamin D be the key to beating coronavirus?”

“Covid-19 deaths linked to Vitamin D deficiency”

Headlines that really catch your eye! However, I certainly hope people read more into it, because by reading those headlines, some people may think a vitamin D tablet is the vaccine we all desire. As we have said all along in this crazy situation, please make sure you do your own research and never just trust a headline to give you all the information you need.

Vitamin D is without doubt a vital nutrient for our general health, and the number of people understood to have below recommended vitamin D levels worldwide is staggering. It is estimated that 30-50% of some countries have lower than normal Vitamin D levels. Interestingly, although the sun is a vital source of it, many countries with hotter climates tend to have an even higher deficiency rate. Researchers in Qatar found that 68.8% of children were deficient in Vitamin D despite the hot climate!

The role of vitamin D in keeping us healthy is nothing new. Previous research has shown that sufficient levels play a big role against fighting respiratory tract infections, such as “flu”. In fact, researchers have gone as far to say that it is one of the reasons these types of viral infections are so seasonal. Due to the lack of sunlight in the winter, vitamin D levels are naturally lower, and they have hypothesised that as being one of the reasons the flu is so much more prominent in the winter. Along with other reasons of course.

The mainstream information on vitamin D is around our skeletal system, however. Supplements are commonly marketed as a nutrient that will give you stronger bones, muscles and teeth. Which is of course true, and one of the many reasons we would always tell our clients how important it is to get enough of it. But let’s take a look at the other reasons why we recommend it. Vitamin D deficiencies have been shown time and time again to have a negative impact on the illnesses and conditions that make people more vulnerable to Covid-19.


The Ageing Population:

Vitamin D status has been shown to reduce significantly with age, particularly in the over 70 population. In Italy, women over 70 were shown to have 35% lower Vitamin D levels than women under 70. The most logical reason for this being that the older population tend to avoid direct sunlight as much as possible, whereas the younger population are more likely to spend a significant amount of time in the sun. It has also been found that around 75% of the institutionalised over 70’s are vitamin D deficient.

Obesity & Type II Diabetes:

I have paired these two together as they are so closely related, with an estimated 85% of people with type II diabetes also being overweight or obese. A recent study on hospitalised Covid-19 patients in New York (therefore were treated as severe cases) found that 41.7% of patients admitted were clinically obese. It was shown as one of the strongest predictors in hospitalisation, behind age (65 years+) and hypertension. Of the hospitalised patients, 33.8% also had type II diabetes. So, there is no more hiding from it, more and more evidence is being produced to show the obese population and those with type II diabetes to be more at risk during this pandemic.

Vitamin D status has long been shown to be related to obesity. Many studies over the years have shown a relationship between low vitamin D levels and high body fat levels regardless of age, ethnicity or geographical area.

The role of vitamin D in type II diabetes is also strong. One study showed that people with higher vitamin D levels were less at risk of type II diabetes by 40%, compared to people with below recommended levels.


Let’s start with the main study that has been making the headlines. A study in Indonesia researched the results of 780 laboratory-confirmed Covid-19 cases. The table below shows the results from the study. Column 1 is Covid-19 cases with vitamin D deficiency, column 2 is cases with an insufficiency, and column 3 is cases sufficient in vitamin D.

Of those cases that were deficient in vitamin D, a whole 98.9% died. The cases that were insufficient, 87.8% died. And the cases that had adequate vitamin D levels, just 4.1% died. Quite astounding numbers, you can see why it has hit the headlines.

In another study, they looked at the number of cases and deaths per country. They then compared that number to the average populations vitamin D levels. As you can see from the graph below, there is an obvious relationship between the populations vitamin D levels and both the number of cases and most importantly, the mortality rate. The trend being, the lower the average vitamin D levels, the higher probability of both covid-19 cases and deaths. Of course there are a few outliers, probably based on how they have controlled the situation, such as Germany.

Below is a table from the same study, showing a breakdown of each European countries results, based on average vitamin D levels, and the number of cases and deaths confirmed (as of April 2020). Interestingly, look at the vitamin D levels of the Southern European countries with hotter climates, such as Spain and Italy.

When I first heard there may be a link between low vitamin D levels and death rate, my first thought was, “well surely that’s not the case, as Spain and Italy are the worst hit and their vitamin D levels should be high”. Their levels are among the lowest 25% in Europe! Now the main reason that is believed for this I mentioned earlier with the elderly population. It is more than likely because the hotter the climate is, the more likely the population is to avoid exposure to the sun. Skin pigmentation has also been shown to reduce the capability of the skin to absorb vitamin D from the UV rays. Pair this with their populations being slightly older on average, particularly Italy, and it could explain why their vitamin D levels are much lower than you would expect.


Here is my view on it and why I put in the title to not treat it as a magic pill. I have already seen reports of people taking this information as “all I need to do is take a vitamin D pill a day and I’ll be alright”.

The question I have for everyone is this; do you think it is probable that one vitamin, that potentially half of the world has insufficient levels of, can be the main reason for the 98.9% of deaths in the above study? Possible, maybe, but probable?

I am not downplaying the role that vitamin D has to play on our overall health. There are huge benefits to having sufficient levels of it, and it is one of the few supplements that I feel there is genuinely no reason to not be taking it. I will explain this a little more in our recommendations.

So the chicken or the egg scenario is this; is the increased chance of death due to low vitamin D levels, or is it because of the comorbidities (the ones discussed earlier in the blog) that are associated with low vitamin D levels, that increase the risk?

One of the trends we see with people with low vitamin D levels is a sedentary lifestyle. Two of the reasons given for low vitamin D levels in obese individuals is lower activity levels and less likely to be exposed to sunlight for a significant period. Excess fat storage has also been shown to lower the availability of vitamin D in the body, even when supplementing to increase intake. 

So for me, that individual taking a tablet a day to boost their levels isn’t going to be enough to help protect them. It may help, but more is required. It is our lifestyles that need to change if we are to reduce our risk.


As I said previously, vitamin D supplementation is a great, or even a necessary, option. The UK in the winter as you know can be very bleak, it can be days before we see any sunshine. This means our vitamin D intake is going to be much lower during this time. Therefore, the need for supplementation becomes greater.

UVB rays account for 90% of our vitamin D intake, so if we are not getting out in the sun, then we must ensure we are still getting enough. UK guidelines can vary, but generally it is recommended that our optimal blood levels are around 70-80nmol/l. If that is the case, then currently only 2 European countries are at optimal levels according to the study mentioned above.

It is very hard to tell just how much exposure we are getting to vitamin D through sunlight, which is why I would recommend supplementing anyway. Especially as generally, vitamin D supplements can be pretty cheap. If you can expose yourself to 15-30 minutes of midday sunlight that can boost your levels. However, absorption can vary from person to person based on pigmentation, amount of clothing on, ability of the body to absorb and store the vitamin, sun cream and how strong the UVB rays are. Quite a lot to think about, which is why we are better being safe than sorry by supplementing.

The NHS have recommended supplementing around 400 IU (international units) of vitamin D3, which is around 10 micrograms. Supplements will generally have both IU’s and microgram amounts so keep an eye out for them. 

From a personal point of view, I feel this number is outdated and does not take into account the fact that many of us have insufficient levels, and we do not get much exposure to sunlight. Many supplements out there will provide a minimum of 2,500 IU’s, add to that plenty of sun exposure and getting some through our diet (oily fish, eggs, fortified products) and we are probably at a more effective number.

So please, get yourself out in the sun, take your supplement, eat good quality nutritious food, and keep on smiling and laughing. Yes, I recommend taking a vitamin D3 supplement, but our overall lifestyle has the biggest part to play here.