Obesity and COVID-19

For months now, we have been hearing that some individuals are at higher risk for getting severe cases of COVID-19. The "high-risk populations" named by the Centers for Disease Control and Prevention (CDC) include those who are of older age or are immunocompromised, and who have underlying conditions such as diabetes or hypertension [1]. Though it seems to get far less attention than conditions such as older age and diabetes, obesity is another condition on the CDC's list.

A number of studies support this decision [3, 4], The situation is rapidly changing, but this is what appears to be the case with obesity and COVID-19.

Weight and COVID-19 Outcomes: The Evidence

The CDC categorizes obesity as having the "strongest and most consistent evidence" for "severe illness from COVID-19," defined as "hospitalization, admission to the ICU, intubation or mechanical ventilation, or death."[5] The evidence is so convincing that while the CDC's original list only included severe obesity (BMI over 40 kg/m²), the most recent list includes all obesity (BMI over 30 kg/m²).

Researchers have collected and analyzed data as the novel coronavirus has swept through the U.S. and world. These are a few findings from studies from around the world, including the U.S., France, and China [6].

• "Severe obesity was a risk factor for hospitalization" among patients with COVID-19 in New York.
• "62% of patients with obesity died of COVID-19, compared to only 36% of those without obesity" in Seattle.
• "62% of patients with obesity required mechanical ventilation, compared to 64% of those without the condition" in Seattle.
• "Having obesity was associated with a 142% higher risk of developing severe pneumonia associated with COVID-19" in China.
• "Patients with obesity were more likely to require invasive mechanical ventilation" in France.

British Prime Minister Boris Johnson has stated his intentions to fight obesity after becoming convinced that his own serious bout with COVID-19 was related to his excess weight. He supports incentivizing doctors to send obese patients to weight loss centers [7].

Why Obesity Might Affect COVID-19

Why does obesity seem to be a risk factor for severe cases of COVID-19? Obesity affects the body in many ways. For example, it affects the respiratory system by raising resistance in the airways and reducing lung capacity, which together can increase the risk for infections from respiratory viruses, such as the new coronavirus, to lead to pneumonia as a complication.

Obesity also interferes with immune function. It is linked to chronic inflammation, as well as arterial stiffness and impaired platelet function (related to blood clotting) [8]. Finally, obesity is a risk factor for other conditions that are linked to severe COVID-19 cases. These include heart disease, hypertension, prediabetes, and diabetes.

Taking Data for What It's Worth

As weary as we may be of hearing about the novel coronavirus, it is still quite new in the eyes of scientists. Our knowledge about it grows daily, and what we think we know today can easily change tomorrow. 

There are several shortcomings in the data so far. For example, the number of studies on obesity and COVID-19 is relatively tiny compared to studies on more established topics. These are some other limitations of the evidence so far.

• Many of the studies are small, including only dozens or hundreds of patients.
• Because of the rapidly-changing nature of the situation and the need for information, research papers may be published more quickly and with less critical review than under normal circumstances.
• It is hard to guess whether obesity may be causing some of the poor outcomes, or whether it may simply be linked due to some other factor.

Still, at this point, the evidence does seem to point to a link between obesity and poorer COVID-19 outcomes, and there does not seem to be any counter-evidence that suggests that obesity is not a concern. At this moment, it seems safer to assume that obesity is a risk factor. 

Recommendations for High-Risk Individuals

The CDC has suggestions for people who are at high-risk for severe cases of COVID-19, including those with obesity [9]. They include the same precautions as everyone else, such as washing hands frequently, wearing a face covering in public, and maintaining social distance from people who are not in your household. 

If you are considering going out or seeing other people, these are some tips and considerations.

• Being outdoors is safer than being indoors.
• Smaller gatherings are safer than larger ones.
• If eating together at a socially distanced meal, it is safest for each person (or household) to bring their own dishes and utensils.
• Getting groceries delivered is safer than going to the store yourself.

The CDC also recommends following your healthcare provider's nutrition and physical activity recommendations.