Why Are People with Obesity More Vulnerable to COVID?

poorer outcomes from infectious diseases, including COVID-19.

Researchers are still working out the mechanisms by which this inflammation occurs. One hypothesis is that when fat cells become overloaded with nutrients, the resulting intercellular stress can trigger an “inflammatory cascade.”

“One way to think about it is: with obesity, people store a lot of substances in the fat cells, but they also begin to release more than normal as they grow,” says Andrew Greenberg, director of the obesity laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University. “These circulate into the blood and bind to immune cells in the liver and muscle. And this leads to the release of inflammatory factors.”

Another possibility is that when fat tissue builds up, it become hypoxic, or lacking in oxygen. This, too, can activate inflammatory pathways.

A third pathway concerns the infiltration of immune cells called macrophages in adipose tissue. In addition, Walsh says, when engorged fat cells begin to die, “the body has trouble ridding itself of this tissue. This contributes to a lot of toxicity and sets off a cascade where all sorts of bad things happen.”

Poor diet can also play a role in increasing inflammation. According to a 2019 paper in the journal Nutrients, the Western diet, which is high in sugar and bad fats and low in complex carbohydrates, fiber and healthy micronutrients, is in itself a risk factor for “metaflammation,” or chronic metabolic inflammation, particularly in people who are overweight. Among the probable mechanisms is that poor diet alters the composition of the intestinal microbiome, encouraging the production of microbial toxins, including lipopolysaccharide (LPS). Obesity can increase the gut’s permeability to those toxins, also known as gut leakiness, allowing them to be released into the bloodstream. When the body senses extra LPS, it induces an inflammatory response from immune cells.

While diet can be harmful and inflammatory, good nutrition can help reduce some of the damage caused by obesity-related issues. Some nutrients, including omega-3 fatty acids, can work to diminish inflammation. One eating plan thought to combat chronic disease is the Mediterranean diet, which is rich in fruits and vegetables, nuts, fish and healthy fats. This diet is thought to provide people with a host of protective compounds, including omega-3s and polyphenols, plant-based compounds with antioxidant properties.

Greenberg says more research is needed to determine whether supplements, including fish oil, fiber, prebiotics and probiotics, can work to reduce inflammation, boost immunity and reverse chronic conditions associated with obesity, such as diabetes. The most tried-and-true approach, though not an easy one, is weight loss, he says. And a small amount can make a difference. “They don’t have to be at their ideal body weight,” Greenberg says. “Even losing 5 to 10 percent of a person’s weight really helps improve their metabolic profile.”

Exercise, even in modest amounts, can also help reduce inflammation. According to a 2017 study published in Brain, Behavior, and Immunity, a 20-minute session of treadmill walking can stimulate an anti-inflammatory response.

Impaired immune function is just one reason obesity raises the risks of COVID-19. Type 2 diabetes, which so often accompanies obesity, also complicates COVID, as does restricted breathing (another consequence of a high BMI). A healthy diet, weight management and exercise help fortify the body in the best of times, and they are even more critical during a pandemic.

This article is part of an editorially independent Springer Nature collection that was produced with financial support from Lonza.