COVID-19 is a confusing disease.
In the same newspaper on the same day, you can read that there are over 50,000 American deaths from COVID-19 but also that 2.7 million New Yorkers may have had completely asymptomatic infections.
Why do some people get so sick that they either die or end up on a ventilator for weeks and lots of others have only mild infection or barely any symptoms at all?
It’s legitimately a multi-trillion dollar question. And no one knows for sure, but there are A LOT of different ideas about what might be going on.
Many people are speculating that extra weight may have something to do with the varying outcomes seen in COVID infection.
The suggestion that obesity is associated with increased risk of severe infection comes initially from an analysis of over 4000 COVID-19 cases at NYU, where they tried to figure out what separated the sickest patients from the least sick ones. After a lot of fancy statistical work, they found the biggest risk factors for severe disease were age over 65 and obesity. The obesity-severe COVID link has subsequently been written about all over the place, and everyone seems to have a theory about why this is so.
This is boring. Do you have anything interesting to add to this discussion?
I’m not sure. This topic has certainly been covered ad nauseum. I’ll try.
Obesity is considered a risk factor for all kinds of diseases - heart disease, diabetes, high blood pressure, stroke, even some types of cancers.
But some people with obesity seem to be metabolically healthy - meaning no manifestations of obesity-related medical conditions, at least for a period of time.
Why is this the case? One idea is that it’s the type of fat we carry that dictates how sick it makes us.
There are two major types of fat that we carry on our bodies - subcutaneous fat and visceral fat.
[I’m leaving brown fat out of the discussion for now, as it is essentially only relevant for infants or adults with significant cold weather exposure]
Subcutaneous fat is sort of like an energy silo. It’s fairly inactive biologically and just serves as a storage bin for excess calories. This is the fat that accumulates beneath the skin and tends to show up more in our butts and thighs.
Visceral fat is the nasty kind that is likely responsible for a lot of the metabolic dysfunction that occurs with obesity. Visceral fat accumulates around our internal organs and functions as a hormone producer - unfortunately the signals that it sends are ones that increase inflammation, raise blood sugar, make our blood more likely to clot, and make us retain salt and water (causing swelling and raising blood pressure).
Because visceral fat tends to collect around our internal organs, waist size is sometimes used as a proxy for how much visceral fat we have and how harmful our fat stores are.
Visceral fat accumulation is probably why obesity increases our risk of high blood pressure, diabetes, heart disease, and cancer. While subcutaneous fat is essentially just an aesthetic inconvenience, visceral stuff is the nasty player behind the scenes.
Unfortunately, you can’t pick where your fat accumulates - this is dictated by your own genetics.
There’s a suggestion that the high incidence of diabetes and metabolic syndrome in South Asians of normal body weight is related to a predisposition to accumulate visceral fat compared to subcutaneous fat.
Wait, I thought that was going to be interesting. And I thought it was going to be about COVID
Well, I personally thought it was interesting. We can agree to disagree there.
There’s a lot out there that’s hypothesized to be related to the association with severe COVID disease in obesity.
Obesity often leads to a low grade inflammation that is associated with immune system dysfunction, with this degree of chronic dysfunction can potentially lead to an immune response that gets out of control when confronted with a viral infection. The degree of chronic low grade inflammation seen in obesity seems to be related to the amount of visceral fat accumulation.
There’s also an idea that the compression of the lungs associated with obesity increases likelihood of needing a ventilator, but I tend to be less persuaded about that aspect of the association.
I suspect that the excess risk of severe COVID infection observed in obesity is related to visceral fat accumulation and the hormonal effects it drives in the body.
In other words, it’s not the presence of fat, per se, that drives excess risk, it is where the fat is located. The relative accumulation of visceral versus subcutaneous fat seems to be what determines whether obesity increases risk of disease or is merely a benign accumulation of fat.
So what does this mean for COVID-19?
In my view, this information emphasizes the importance of not letting the stress of our economic collapse and fear of getting sick lead to us not paying attention to the usual things involved in healthy behaviors - exercise, eating vegetables, not having cake for breakfast.
The observation that obesity is associated with an increased risk of severe COVID infection tells me that we should be using our isolation/quarantine as an opportunity to focus on our own health and well being - by taking care of ourselves throughout these socially distanced times, we are doing everything in our power to decrease our COVID risk if we happen to get infected.
Fortunately, visceral fat is lost preferentially relative to subcutaneous fat when someone begins to lose weight. The phenomenon of initial visceral fat loss is why losing only a small amount of weight can have a big impact on health.
So if you’ve made it this far in the newsletter, I would encourage you to feel as though this information gives you an element of control over your health. Maximizing your healthy habits during quarantine - or at least recognizing that dessert as a stress reducer may be counterproductive - puts you in the driver’s seat.
This isn’t going to completely change the trajectory of your COVID course if you happen to get sick, but perhaps it is a small step in the right direction (and probably more beneficial than hydroxychloroquine).