The Interesting Link Between Weight and the Flu

Although the new coronavirus may be grabbing all the headlines lately, a more likely danger for most people is influenza, also known as the flu, which is raging in the U.S. right now. The Centers for Disease Control (CDC) have reported that nearly 19 million people in the country have been sickened with the flu since the season began in November, and about 180,000 have been hospitalized with it.

For those carrying extra weight, the flu can be even more challenging, both for them and those around them. Here are three big reasons why:

During the 2009 flu season, a particularly active year for the virus, health officials began to notice people who were overweight, and especially people who were obese, seemed to be hospitalized for the flu more often. That led the CDC to investigate, and they determined that obesity did, in fact, raise the risk of serious flu-related complications.

That’s likely because the virus seems to spread deeper into the lungs for those who are obese, according to Stacey Schultz-Cherry, PhD, an infectious disease specialist at St. Jude Children’s Research Hospital.

Not only does that increase the risk of more severe flu symptoms, but she says it creates a “perfect storm” that can lead to additional viral and bacteria growth — which means a secondary infection can occur more easily.

For those who already have other health conditions, like diabetes or other metabolic disorders, this can make the flu a very serious health situation, says Schultz-Cherry. The immune system, already working hard to deal with a chronic condition, would have to go into overdrive to handle the flu — and then if a secondary infection develops on top of that, it would be a major concern.

Compounding the problem is the fact studies indicate the flu shot doesn’t work as well for those who are obese. Recent research suggests those with obesity may be twice as likely to get the flu even if they’ve had a vaccination, compared to those of lower weight.

In terms of why, researcher Melinda Beck, PhD, of the University of North Carolina Gillings School of Public Health, says the immune function of people who are obese may be less efficient, especially their T-cells, which help modulate the body’s immune responses. These are the cells that “remember” a virus, so when it’s encountered again, the immune system can respond much faster.

Impaired T-cell function, paired with possible other immune system challenges, could make a flu shot less effective.

Not only are people who are overweight and obese more susceptible to the flu and more serious complications, but they may also be “shedding” the virus for a longer time, which means potentially spreading the infection to others.

A recent study found obese adults with influenza and who had flu symptoms shed the virus for 42% longer than adults who had the flu and were not obese. Among those who had only mild symptoms or none at all, but still tested positive for the flu, the difference was even greater — they shed the flu for 104% longer than non-obese adults with the flu.

“All of this research is highlighting the fact that excess weight isn’t just a risk factor for diseases like diabetes, cardiovascular issues and certain cancers, it can also be a risk factor for communicable diseases like influenza,” says Schultz-Cherry.

Whether or not you’re carrying extra weight, it can be helpful to get more serious about immune-strengthening strategies right now, as cold and flu season still rages on.

Consider sure-fire tactics like staying hydrated, washing your hands much more often, eating more fruits and vegetables, limiting your interaction with sick people, getting more activity, not touching your face and working to decrease stress.

Here’s a great first step toward implementing those good habits: Get enough sleep. Several studies have associated sleep deficiency with poor lifestyle habits like overeating, sedentary behavior and eating highly caloric food.

“The connection between good sleep and good immunity is very strong,” says Dr. W. Christopher Winter, president of Charlottesville Neurology and Sleep Medicine. “Before summer comes, this is a good time to set solid habits that will carry you through cold and flu season. That pertains to sleep, but also to other healthy lifestyle changes, too.”