Is There a Relationship Between Asthma and Obesity?

Question: Is There a Relationship Between Asthma and Obesity?

Answer: Over the past few decades, asthma and obesity have both become more common. In fact, at least half of the United States population is overweight or obese, while asthma affects nearly 8% of the U.S. population. Being overweight, especially obese (a body mass index, or BMI, greater than or equal to 30), is a risk factor for developing asthma. In addition, asthmatics that are obese are likely to have more severe asthma than those who are not obese.

Studies have also shown that obese asthmatics can have significant improvement of their asthma with weight loss. Asthmatics that are severely overweight that lose weight, either through diet or surgical methods (such as bariatric surgery) improve their asthma symptoms, with less medication needs, less hospitalizations and better lung function.

There are various reasons why obesity worsens asthma. First, obese asthmatics have smaller lung capacity, which causes the muscles around the lung airways to contract more, resulting in more asthma symptoms. Second, the small airways in obese asthmatics are more likely to stay closed during normal breathing, causing less oxygen exchange in these airways and placing the person at risk for pulmonary hypertension. Obesity also appears to cause chronic inflammation in the body, which in asthmatics resulting in worsening asthma symptoms. Lastly, obesity places a person at increased risk for gastroesophageal reflux disease and sleep apnea, both of which can worsen asthma.

_Sources:

Litonjua AA, Gold DR. Asthma and Obesity: Common Early-life Influences in the Inception of Disease. J Allergy Clin Immunol. 2008; 121:1075-84.

Shore SA. Obesity and Asthma: Possible Mechanisms. J Allergy Clin Immunol. 2008; 121:1087-93.

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