Asthma and obesity have both been on the rise in the U.S. over the last decade. More than one in three Americans is now obese and more than half are overweight. About 7% of American adults have asthma, which translates to about 15 million people living with symptoms of asthma. Past research has indicated that the rise of the two might be linked to each other and new research out this week has gone further to see if obesity might be contributing directly to a person’s asthma symptoms.
What is asthma?
Asthma is a disease of the airways that convey air to the lungs. These airways are covered in muscle that can relax or contract depending on the body’s needs. In most people, this contraction and relaxation happens in a way that helps with normal breathing. People with asthma have airways that are overreactive. The muscles of these airways can get set off when a person does exercise, when they breathe cold air or when a chemical irritant hits their lungs. They respond by heavily contracting these muscles, which closes down the airways and makes it tough for air to get through.
The reaction also triggers widespread inflammation of the lining of these airways. They become inflamed and swollen and start pumping out mucus to try and protect against the offending irritants, which further clogs the airway. When these symptoms are severe enough, they’re called an asthma attack. Without medications to shut down this process, an asthmatic’s airways can close completely and they can die.
What is the relationship between asthma and obesity?
Groups of researchers in the past had noticed that places with high levels of obesity also tended to have high rates of asthma both in children and in adults. They wondered if the two conditions might be linked given that they seemed to show up in the same people. This early research revealed that people who were obese were on average about 50% more likely than someone with normal weight to have asthma, which is a big jump in risk. On top of that, risk goes with BMI. Risk for asthma increases by about one third for every three BMI points. For every one BMI point increase, a person’s airway also becomes more reactive, a key symptom that can lead to asthma.
While this relationship appeared clear, researchers didn’t know which direction the relationship went. Was it that being an asthmatic led to obesity, perhaps because asthmatics have truoble exercising, or was it that being obese was somehow leading to asthma? This study hoped to understand which was causing which in hopes that treating one could treat the other.
What did the researchers do and what did they find?
The team recruited 22 obese adults with asthma and split them into two groups. The experimental group was put on a diet for three months and went to weekly sessions with health professionals to learn about how to manage their weight effectively. The other group didn’t do anything during the same three months to try and lose weight. The researchers tested how reactive the airway of each participant was before and after the study as a measure of their asthma symptoms. They also tested how well their lungs functioned, how often they had to use their asthma medications and asked them about their overall quality of life during the study.
The team found that losing weight led to direct improvements in how well the participants’ lungs functioned and translated into less need for asthma medications and better quality of life. Of note, those in the weight loss group also started exercising more and the researchers think that this increase in exercise may have contributed to the improvement in asthma symptoms.
How does this apply to me?
Being obese is a risk factor for asthma, which means that many Americans are at risk and probably have hyperactive airways even if they don’t have outright asthma. The good news here is that dropping weight also drops your risk. If you already have asthma, this study shows that starting an exercise regime and losing weight will help improve your asthma symptoms.