A heart shaped bowl with fruits and vegetables next to diabetes testing to show how obesity and immunity are connected.

The Connection Between Obesity and Immunity

I know it’s easy to feel helpless in the face of this pandemic. But I don’t believe in feeling helpless—I believe in being empowered. And I believe in focusing on what you CAN do, not what you CAN’T do. 

That’s why I want to share some good news with you: You can take action right now to slash your risk of infection, or lower your odds of getting seriously ill if you do catch this bug.

I know you’re already doing all the right things to avoid this virus: washing your hands, sheltering in place, and wearing a mask in public. But eventually, you’re going to go back out into that big world. When you do, this virus will still be out there—and there’s a good chance that it will sneak up on you sooner or later, even if you keep following safe practices. 

So how can you strengthen your armor so you can fight off this bug if it attacks? Here’s the single biggest step you can take: commit to losing your extra pounds. 

I know this means bucking the trend, because most people are tucked away on the couch loading up on chips and ice cream. But if you need motivation to start getting rid of those extra pounds, you can’t get a better incentive than this: it can help to save your life in this pandemic, especially if you’re obese or heading in that direction. (Better yet, losing just a little can make a big difference—something I’ll talk about shortly.)

Here’s the deal. Being overweight or obese is one of the biggest risk factors for severe COVID-19 infection, especially among younger people. In fact, among people in this age group, obesity can increase the risk of serious symptoms more than six-fold.

That’s scary, I know. But it’s no surprise to me, because the scientific literature shows a powerful link between excess weight and impaired immune function.

What is the link between excess weight and impaired immune function?

  • Both human and animal studies show that obesity can lead to “altered lymphocyte numbers and reduced lymphocyte responsiveness to mitogen stimulation, dysregulated cytokine expression, decreased natural killer cells, macrophage and dendritic cell functions” (translation: A highly impaired immune system, leading to a higher risk of infection or a worse outcome).

  • Obesity increases the risk of hospitalization and death due to the flu. People who are overweight or obese also shed more virus particles and shed them for a longer time, endangering others.

  • Hospitalized patients are also more likely to develop secondary infections—a problem we’re currently seeing with COVID-19— if they are obese.

Why is extra weight dangerous? 

Extra weight causes inflammation.

Your subcutaneous fat (that’s “the inch you can pinch”) is healthy fat. But your visceral fat—the deep-down fat that wraps around your organs—is a witch’s cauldron that’s constantly brewing up inflammatory chemicals and releasing them into your body. 

This is particularly dangerous if COVID-19 strikes, because the biggest offender in this virus is the cytokine storm that can overwhelm your body with inflammatory molecules. If you’re already chronically inflamed, this cytokine storm can hit you even harder.

Leptin resistance can occur with excess weight.

You might already know about leptin from my posts about how it helps to control appetite, but it turns out that it has another important job.

Let’s start with the back story. Leptin, a hormone produced by your fat cells, tells your brain if you’re full or hungry. That’s why I call it your “hunger trigger.”

However, if you’re obese, this trigger doesn’t work right anymore. That’s because your leptin concentration correlates with your percentage of body fat. So more body fat equals more leptin. 

You’d think that would make you less hungry, right? But unfortunately, when your levels of leptin are always high, your brain stops listening to it. This is called leptin resistance, and it means that you’re hungry even when your body has plenty of food.

So… what does this have to do with immunity? It turns out that leptin doesn’t just affect your appetite—it affects your immune system, too. We’re learning that leptin influences an incredible range of immune system responsesboth inflammatory and anti-inflammatory. Leptin resistance throws a monkey wrench into this intricate process, wreaking havoc on your immune function.

Extra weight can lead to diabetes.

Being overweight or obese dramatically increases your risk for type 2 diabetes, and infections are more common and often more serious in diabetics. One reason is that high blood sugar levels cause the body to produce molecules that weaken its infection-fighting defenses

How can I decrease my risk?

Enough bad news—now for the good news!

I know all this bad news is hard to hear if you’re overweight or obese. But here’s the very, very good news: every pound you lose right now will improve your immune function and help to protect you against COVID-19. 

In fact, one exciting study shows that even a small amount of weight loss starts to reverse immune system damage. The authors of this study found that simply losing about 13 pounds was enough to “bring the pro-inflammatory nature of circulating immune cells back to that found in lean people.” This means that you can start healing your immune system fast.

So here’s my challenge: While everyone else is using this pandemic as an excuse to gain weight, use it as your motivation to LOSE weight. And while the people around you are feeling helpless, feel empowered—because this is one COVID-19 threat you can face down and crush.

a tray of fruits and vegetables with a heart shaped sign to help reduce the connection between obesity and immunity.

Every crisis brings an opportunity to be braver than you believe, stronger than you feel, and greater than you think. Make this yours!

Keep Positive and Stay Healthy!

Dr. Kellyann