Does Obesity Cause Asthma? What We Know

Many of us have struggled with our weight at one time or another, and lot of us have also given up trying to lose weight because exercise made it hard for us to breathe.

A growing body of evidence suggests that our frustration isn’t all in our heads. We have two very real problems: obesity can increase the risk of asthma and asthma can contribute to obesity.

“The idea that obesity and asthma may be linked has become more widely accepted,” says Beth A. Miller, MD, associate professor at the University of Kentucky College of Medicine in Lexington and director of the UK HealthCare Asthma, Allergy, and Sinus Clinic.

That’s because doctors who have long suspected asthma and obesity are connected now have lots of data to back them up.

For starters, obesity rates are higher among people with asthma, according to the U.S. Centers for Disease Control and Prevention (CDC). Here are some numbers that help illustrate the situation:

  • Nearly 39 percent of adults with asthma are obese, compared with 27 percent of adults without asthma.
  • Among all American adults, about 7 percent have asthma, while among overweight adults, almost 8 percent have asthma and among obese adults 11 percent have asthma, according to a recent CDC report. Asthma rates are also rising faster among people who are overweight.

Either Asthma or Obesity in Childhood Appears to Contribute to Development of the Other

The connection between asthma and obesity may start long before adulthood, research suggests.

A study published in December 2018 in the journal Pediatrics found that overweight and obese children had a higher chance of developing asthma. For the more than 500,000 kids in the study, overweight children had an 8 to 17 percent increased risk of developing asthma compared with their peers who maintained a healthy weight. And the obese youth in the study were at a 26 to 38 percent increased risk of asthma. This was based on records of doctor checkups and prescriptions for breathing medication.

The data suggests that 23 to 27 percent of new asthma cases in children with obesity are directly attributable to obesity and that as many as 10 percent of cases of pediatric asthma could be avoided if children were all a healthy weight, the researchers report in the study.

A separate study published in September 2018 in the European Respiratory Journal followed more than 20,000 kids and found obese toddlers with asthma were 66 percent more likely to be obese later in childhood compared with kids who didn’t have the breathing disorder when they were younger.

Toddlers in the study with active asthma — meaning they had a physician diagnosis and wheezing episodes or asthma attacks within the previous year — were twice as likely to be obese by the time they were 8 years old than toddlers without asthma or wheezing, the study also found.

The data suggests that asthma certainly may be contributing to the obesity epidemic, says Frank Gilliland, MD, PhD, a professor of preventive medicine at the Keck School of Medicine at the University of Southern California in Los Angeles, who participated in the study.

“We urgently need to know if prevention and adequate treatment of asthma can reduce the trajectory toward obesity," he adds.

But, when it comes to obesity, it’s clear that it’s a difficult trajectory to turn around. Recent research also suggests that most obese kids will become obese adults.

Obese 2-year-olds have a 75 percent chance of still being obese by age 35, and obese 19-year-olds have an 88 percent risk of being obese by 35, according to a pooled analysis of data on more than 40,000 children and adults in a report published in November 2017 in The New England Journal of Medicine.

Obesity Increases Rates of Severe Asthma, Too

While some kids with asthma may outgrow the condition as they get older and their lungs get stronger, this happens less often with severe asthma, according to the Mayo Clinic. Severe asthma defines cases of the lung condition where symptoms appear more frequently (twice a week or more) and require more medication to control.

Data shows that obese children and adults are more likely to have severe asthma than healthy-weight individuals, according to a report published in April 2018 in the Journal of Allergy and Clinical Immunology.

And when people with asthma are obese, they’re more prone to asthma attacks and have more frequent hospitalizations, according to a study published in May 2016 in the American Journal of Respiratory Cell and Molecular Biology. Obese people with asthma are also less likely to improve with standard medicines prescribed to keep symptoms under control, according to that study.

The Mechanism Driving the Obesity-Asthma Link

Researchers are currently investigating the mechanisms that would explain exactly how asthma might cause obesity — or how obesity might cause asthma. But they do not yet have a completely clear answer.

Excess weight around the chest and abdomen might constrict the lungs and make it harder to breathe, according to the American Lung Association. Fat tissue also produces inflammatory substances that could impair lung function and lead to asthma.

Obesity can also trigger the development of so-called cardiometabolic risk factors, like high cholesterol and diabetes, all of which can also contribute to breathing difficulties. And obesity may also make people more susceptible to many of the strongest risk factors for asthma, like exposure to allergens, chemicals, cigarette smoke, and air pollution.

How obesity contributes to asthma in any one individual is likely dependent on a variety of factors, according to the American Lung Association.

How Losing Weight Can Help You Manage Asthma

Even though researchers do still have some questions about the mechanisms behind how asthma and obesity are related, it’s important to know that in terms of preventing and managing either condition, maintaining a healthy weight can help.

A study published in October 2018 in the Journal of Asthma found that obese patients with asthma who lost weight experienced improved breathing function and quality of life — particularly when they shed more than 5 percent of their weight.

Weight loss would certainly be a recommended part of any asthma treatment plan for someone who is obese, particularly for patients with poorly controlled asthma requiring frequent hospitalizations, notes Dr. Miller. While it’s critical to consider other factors, such as smoking and allergies, which also need to be managed, obesity shouldn't be overlooked in asthma management.

"It's definitely an important component of their disease that needs to be considered," stresses Miller.

Additional reporting by Lisa Rapaport

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