Obesity and COVID-19:

When Two Pandemics Collide

Scott S. Russo, MD



As of the writing of this article in late fall of 2020, it’s become clear that nearly everyone in the world, either directly or indirectly, has been affected by COVID-19. Many communities worldwide are now in secondary lockdowns due to a spike in overall cases, as well as a sudden increase in COVID-19 infections requiring hospitalization. Originally, this happened only in elderly people whose immune systems were already compromised by conditions that frequently appear in that age group, such as type 2 diabetes mellitus, cardiovascular and pulmonary disease, two conditions I’ll cover in forthcoming articles, detailing how they interact with COVID-19.

In recent months, COVID-19 has begun to ravage populations it originally ignored, such as adults and children with healthy immune systems. However, recently one group that’s seen greater and greater numbers of infections and deaths are people who are overweight, if not obese—a BMI (Body Mass Index) of 30% above a healthy weight for height and build—or super (morbidly) obese, which entails a BMI of 40% or greater. (1)

Why is this?

Obesity, which is defined as a weight with a BMI (Body Mass Index) of 30 or greater, is associated with high amounts of excess fat. This condition by itself, can be an extremely unhealthy state. When a person’s body is stressed by excess weight it might not provide the necessary attention to keeping the immune system working to resist viral invaders. An obese person may not have any secondary conditions such as diabetes, high blood pressure or cardiovascular disease, but, because the person’s system is already in a precarious state, a COVID-19 infection can instigate the development of these conditions, creating an even more fertile environment for the virus’s virulent and destructive nature (in forthcoming articles, why this is will be explained in greater detail—as well as ways this can be avoided). (4)

Even if a person’s immune system is in a pristinely healthy state, when something as harmful as COVID-19 infects someone, it becomes overwhelmed. This is why we’re seeing an increase of cases in healthy adults and children—and an increase in fatalities in those cases. But for someone who is obese, even if they don’t have the secondary conditions that often accompany that state, their system is more easily overwhelmed.

This happens because, as mentioned above, obesity stresses a person’s immune system. We often think of stress as an emotional state linked to overwork or frustrations of some kind. But stress is also physiologic. Stress produces a hormone called “cortisol,” which, in small doses, is fine. But if there’s a continuous flow of it through a person’s body, the body turns away from maintaining optimal health and towards eradicating what’s essentially becoming a poison.

An obese person could be emotionally quite happy, but, because of the stress of excess weight, he or she is unknowingly in a constant state of physiological distress. That means, if they’re exposed to, and become infected with, COVID-19, the compromised immune system is unable to fight the virus with optimal strength. Because stress, whether emotional or physical, weakens a person’s immune system, an infection by COVID-19 can either reveal previously-undetected secondary conditions (like diabetes or cardiovascular disease) that the person already had—or the virus can cause one or more secondary conditions to develop due to the extremely compromised—and now completely overwhelmed—immune system.

An additional problem with COVID-19 is the body over-responds and releases an excess of inflammatory molecules (cytokines) designed to fight the infection. But instead of doing so, the molecules become “confused” and begin damaging the tissues they’re meant to protect. This release of inflammatory cytokines means that COVID-19 is reacting similarly within a young and obese person as it does within an elderly person of a healthy weight. The difference is that becoming elderly and developing common secondary conditions associated with increased age isn’t preventable. Obesity is. This is why aging isn’t considered a pandemic—unlike a disease (Covid-19) that has infected a great number of people on every continent—and obesity are. Obesity, in and of itself, is deadly on its own. When it “collides” with COVID-19, the possibility of death increases enormously. (2)

According to the World Health Organization, the number of obese people worldwide has tripled since 1975. Other facts include:

  • In 2016, more than 1.9 billion adults, 18 years and older, were overweight. Of these over 650 million were obese.
  • 39% of adults aged 18 years and over were overweight in 2016, and 13% were obese.
  • Most of the world's population live in countries where overweight and obesity kills more people than underweight.
  • 38 million children under the age of 5 were overweight or obese in 2019.
  • Over 340 million children and adolescents aged 5-19 were overweight or obese in 2016 (6)

We aren’t exactly sure why, at this time, obesity and COVID-19 mix in such a deadly way. It appears to have something to do with how the virus attacks the person. It seems COVID-19 has a preference for fatty tissue—especially what collects in the abdominal cavity. I’ll go into more detail about this below.

First, an explanation of what a “coronavirus” is. A “coronavirus” is named from the description of how the virus looks under magnification—like a sun with many flares coming from its surface, as shown in the picture below:

The “flares” are surface proteins used by the virus to attach itself to human tissues. The “19” in Coronavirus 19 refers to the year of identification of this coronavirus. You may see the disease referred to as SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2).

Typically, the first cells it tends to attack are the pneumocytes, which are major lung cells. What happens is the cells undergo a massive inflammatory response causing fluid to leak from local blood vessels and filling the lungs (creating the difficulty for breathing). As a result of this edema, the lungs stiffen and resist expanding lessening the transfer of oxygen across the alveoli or small air sacs making it difficult to breathe. As the lung cells die, they no longer perform in the transfer of oxygen into the bloodstream affecting all tissues in the body. (3,9)

So why are COVID-19 and obesity such a deadly combination?

A person, healthy or otherwise, can, of course, have a severe reaction to the flu. It appears that the reason COVID-19 is so destructive and more lethal than a “standard” flu is its ability to latch onto a susceptible cell and cause infectivity in a more aggressive and accelerated manner. Another possibility is the exacerbation of a body’s already inflamed condition brought on by excess fat. Obesity is associated with inflammation which is linked to elevated levels of circulating cytokines. These cytokines are proteins that modulate functions and processes within and between individual cells. They are critical in the defensive response to infections, cancers and other conditions and help to maintain the bodies’ homeostasis and health. (1, 5)

If the body is already in a state of inflammation—such as with obesity—these cytokines, already present, may be prevented from performing their function of creating homeostasis and optimal health. With the introduction of COVID-19, they are further dysregulated, which is not generally seen in “standard” flus. Our knowledge of this cytokine dysregulation is still in its developmental phase. However, it appears that the impact of Covid-19 on a patient depends on the patient’s genetic makeup. And with certain patients the virus stimulates inflammation (inflammatory phenotype) and in others it results in a more targeted immunosuppression. When compared to influenza, those Covid-19 patients exhibiting the immunosuppression phenotype are more likely to suffer acute respiratory failure, require mechanical ventilation and ultimately die. While we know, Covid-19 and influenza patients share similar medical conditions, like kidney disease and dementia, the Covid-19 patients were more commonly obese and suffered from diabetes and hypertension at a higher rate than a person suffering from the flu. (8, 1, 2) 

Where do we go from here?

First, I want you to understand that the information provided in this article is meant to help you understand how and why obesity and COVID create a possibly deadly combination. Outline their separate but interwoven health effects and provide a foundation for a deeper conversation on approaches to manage these serious life-threatening conditions.  In the next article, I will discuss nutritional approaches to the treatment of patients suffering with Covid-19.

Secondly, I want to create understanding that this knowledge isn’t meant to scare you. Rather, it’s our belief at Nutrifuel Nutrition that the more information someone has about a condition, the easier it is to combat it.

Thirdly, this knowledge leads to your developing a greater capacity to create, unique to you a path towards an optimal level of health. Here at Nutrifuel Nutrition, we believe that doing so is even easier by helping you create a support system—a team—that is tailor-made to your specific goals. This makes reaching them even easier.

At Nutrifuel Nutrition we provide a wealth of tools for you to take advantage of, such as supplements and food plans—as well as coaches whose focus is to help you discover the optimal path and products that fit your needs, as well as provide support for personal growth in health and life.



  1. Beshbishy, Amany Magdy, et al. “Factors Associated with Increased Morbidity and Mortality of Obese and Overweight COVID-19 Patients.” Biology, vol. 9, no. 9, 2020, p. 280., doi:10.3390/biology9090280. 
  2. Kalligeros, Markos, et al. “Association of Obesity with Disease Severity Among Patients with Coronavirus Disease 2019.” Obesity, vol. 28, no. 7, 12 June 2020, pp. 1200–1204., https://doi.org/10.1002/oby.22859.
  3. Machhi, Jatin, et al. “The Natural History, Pathobiology, and Clinical Manifestations of SARS-CoV-2 Infections.” Journal of Neuroimmune Pharmacology, vol. 15, no. 3, 2020, pp. 359–386., doi:10.1007/s11481-020-09944-5.
  4. MacMillan, Carrie. “Obesity Emerges as Risk Factor for Severe COVID-19 Illness.” Yale Medicine, 10 Aug. 2020, www.yalemedicine.org/stories/obesity-covid-19/.
  5. Manna, Prasenjit, and Sushil K Jain. “Obesity, Oxidative Stress, Adipose Tissue Dysfunction, and the Associated Health Risks: Causes and Therapeutic Strategies.” Metabolic syndrome and related disorders 13,10 (2015): 423-44. doi:10.1089/met.2015.0095
  6. “Obesity and Overweight.” World Health Organization, World Health Organization, www.who.int/news-room/fact-sheets/detail/obesity-and-overweight.
  7. Petrakis, Demetrios, et al. “Obesity a Risk Factor for Increased COVID19 Prevalence, Severity and Lethality (Review).” Molecular Medicine Reports, vol. 22, no. 1, 2020, pp. 9–19., doi:10.3892/mmr.2020.11127.
  8. Piroth, Lionel, et al. “Comparison of the Characteristics, Morbidity, and Mortality of COVID-19 and Seasonal Influenza: a Nationwide, Population-Based Retrospective Cohort Study.” Lancet Respir Med, 17 Dec. 2020.
  9. Sharma, Atul, et al. “Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2): a Global Pandemic and Treatment Strategies.” International Journal of Antimicrobial Agents2020, vol. 56, 2020, pp. 1–13., https://doi.org/10.1016/j.ijantimicag.2020.106054.
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