How Excess Body Fat and Inflammation Increase the Risk for Serious Complications from COVID-19

The Centers for Disease Control and Prevention (CDC) lists obesity as a health condition that puts individuals at an increased risk of severe COVID-19 illness. Now, however, the CDC is also warning that adults of any age who are simply overweight might also be at an increased risk. Part of the reason is that being overweight can cause chronic inflammation and impair immunity, conditions that can make an individual more susceptible to severe complications from COVID-19.¹ 

Obesity worsens outcomes from COVID-19

At the time of this writing, COVID-19 hospitalizations across the United States are skyrocketing, although we are fortunately on the brink of distributing a vaccine nationwide. 

Since the beginning of the pandemic, the world's scientific community has rushed to learn about this virus that has claimed many lives around the globe. As our understanding has evolved and trends have emerged, it has now become clear that overweight and obese individuals are more at risk of developing severe complications from COVID-19.^2,3

An international research team recently collected data from peer-reviewed papers that included 399,000 COVID-19 patients. They found that an obese individual who contracted COVID-19 was 113-percent more likely to be hospitalized than a person at a healthy weight. In addition, an obese patient was 74-percent more likely to be admitted to an intensive care unit and 48-percent more likely to die.³ 

In another report, researchers analyzed the records of 3,615 symptomatic patients who tested positive for COVID-19 between March and April 2020. Patients younger than age 60 with a body mass index (BMI) between 30 and 34 were 1.8-times more likely to receive critical care and be hospitalized in an intensive care unit compared to individuals with a BMI lower than 30.⁴ 

BMI measures your weight in relation to your height, providing a score that categorizes your weight. BMI most often correlates with total body fat, which means that as a BMI score increases, so does a person’s total body fat. Healthcare professionals are now using BMI to assess a person’s risk for developing various diseases and health conditions.

The Connection between body fat, inflammation, and the immune system 

Being obese is associated with several adverse health conditions that increase the risk and severity of COVID-19, including high blood pressure, heart disease, diabetes, chronic kidney or liver disease, and cancer.^1,2

In addition, being overweight can cause chronic, low-grade inflammation.⁵ In turn, chronic inflammation can intensify severe complications from COVID-19.^1,2,3

Inflammation is a part of the body's normal response to infection or injury. When the immune system detects an invading virus or injury, it releases chemical messengers called cytokines. These cytokines provide instructions to the cells on how to respond to the illness or injury. One of the immune responses that cytokines can trigger is inflammation. It’s the reason that skin surrounding a cut becomes red or swollen, and why your head gets stuffy when you have a cold.

Fat cells also secrete cytokines that can cause inflammation. And cytokines themselves can stimulate the liver to produce other inflammatory proteins.^5-7 Although cytokines help your body fight off and kill infections, too many cytokines can have a negative effect by overwhelming the body and resulting in a damaging scenario referred to as a "cytokine storm."^2,7

A COVID-19 "cytokine storm" is dangerous for overweight individuals

A cytokine storm is an uncontrolled and overwhelming immune response that leads to reduced oxygen in the blood, fluid build-up in the lungs, difficulty breathing, organ damage, and many other serious complications. Complications from a cytokine storm are thought to be a major factor in the death of COVID-19 patients.^2,3,7

A cytokine storm can occur when too many viruses, bacteria, or other pathogens enter the body at the same time. Because nearly every organ has cytokine receptors, almost every part of the body is susceptible to the negative effects of a cytokine storm.^2,3,7

Overweight patients – who already have higher levels of cytokines and chronic inflammation – have a harder time weathering a COVID-19 cytokine storm. The body simply becomes overwhelmed and experiences multi-system failures.^2,3,7

How to reduce inflammation and boost your immunity 

The pandemic is occurring at a time when the prevalence of being overweight and obese is increasing around the world. According to the CDC, three-fourths of adults older than age 20 in the United States are either overweight or obese.⁸

While weight loss takes time, there are ways to decrease inflammation and improve immunity that you can do right now. One is to become more physically active. Many studies show that exercise protects against viral infections, including influenza and the rhinovirus, a cause of the common cold. In addition, exercising at moderate to vigorous intensity improves immune responses to vaccinations.^9-11

To learn more about how physical activity can reduce inflammation and increase your immunity, read: A Mayo Clinic Doctor’s Advice – Boost Your Immunity with Physical Activity.

In addition, ample evidence shows that eating the right food can reduce inflammation in the body and strengthen immunity.¹² To learn more, read: A Mayo Clinic Doctor’s Advice – Foods that Boost Immunity.

COVID‐19 is an unparalleled event in modern human history. It has changed human lives and societies entirely. Maintaining a healthy weight, eating well, and remaining fit can help keep you healthy – during and beyond the pandemic.

References

1. The Centers for Disease and Control. Coronavirus Disease 2019 (COVID 19). https://www.cdc.gov/coronavirus/2019-ncov/need-extra-precautions/people-with-medical-conditions.html#obesity. [Accessed December 2, 2020.]
2. Sanchis-Gomar F, Lavie C, Mehra M, et al. Obesity and outcomes in COVID-19: When an epidemic and pandemic collide. Mayo Clin Proc 2020;95(7):1445-1453.
3. Popkin B, Du S, Green W, et al. Individuals with obesity and COVID‐19: A global perspective on the epidemiology and biological relationships. Obes Rev 2020;21(11):e13128.
4. Lighter J, Phillips M, Hochman S, et al. Obesity in patients younger than 60 years is a risk factor for COVID-19 hospital admission. Clin Infect Dis 2020;71(15):896-897. 
5. Wisse B. The inflammatory syndrome: The role of adipose tissue cytokines in metabolic disorders linked to obesity. J Am Soc Nephrol 2004;15(11):2792-2800.
6. Makki K, Froguel P, Wolowczuk I. Adipose tissue in obesity-related inflammation and insulin resistance: cells, cytokines, and chemokines. ISRN Inflamm 2013;:139239. 
7. Sinha P, Matthay M, Calfee C. Is a “cytokine storm” relevant to COVID-19? JAMA Intern Med 2020;180(9):1152-1154. 
8. The Centers for Disease and Control. Obesity and Overweight. https://www.cdc.gov/nchs/fastats/obesity-overweight.htm. [Accessed December 2, 2020.]
9. Simpson R, Kunz H, Agha N, Graff R. Exercise and the regulation of immune functions. Prog Mol Biol Sci 2015;135:355-380. 
10. Martin S, Pence B, Woods J. Exercise and respiratory tract viral infections. Exerc Sport Sci Rev 2009;37:157-164.
11. Jones A, Davison G. Exercise, immunity, and illness. Musc Exer Physiol 2019;317‐344. 
12. Minihane A, Vinroy S, Russell W, et al. Low-grade inflammation, diet composition and health: current research evidence and its translation. Br J Nutr 2015;114:999-1012.