Asthma and Obesity
Obesity is on the rise in the United States. It is well known that obesity can cause diabetes and heart disease and that part of this is from chronic inflammation triggered by obesity. So, if asthma symptoms are caused by inflammation in the lungs, are there links between asthma and obesity as well?
Obesity is defined as having a Body Mass Index (BMI) of 30 or greater. More Michiganders are obese than were 10 years ago- who is obese?
- 31% of adults
- 13% of 2- to 4-year-olds from low-income families
- 15% of 10- to 17-year-olds
- 13% of high school students
In Michigan, 13% of obese adults say they have asthma, and 10% of non-obese adults say they have asthma. The association between asthma and obesity has been shown in many studies, but asthma is a complex disease and there may be many reasons for the link. We often think of asthma being associated with allergic triggers and atopy (have allergy symptoms like runny nose and eczema), but obesity does not appear increase the severity or incidence of allergies.
Asthma control assessments are based on how often symptoms, such as shortness of breath and inability to take part in physical activity, happen, and how severe the symptoms are. Obesity itself can cause many of these symptoms due to the mechanical changes caused by having more abdominal fat on the lungs. Many of the reasons why obese asthmatics feel that their asthma is under poor control may not be from an increase in airway inflammation or lung function. In fact, some studies have shown that there is little difference between the lungs of obese and slim patients, but obese patients overuse their rescue inhalers (e.g. albuterol). This shows that they think differently about their asthma control although their lungs are working in the same way.
Although obesity may not cause asthma in many cases, there is clear evidence that obesity changes how people respond to chronic and acute asthma treatments. Obese asthmatics need more intensive treatments when they are hospitalized. Inhaled steroids are less effective in controlling obese asthmatics than non-obese asthmatics.
Clinicians caring for obese asthmatics need to be aware that there are different types of asthma, and treatment is not "one size fits all." We now understand that there are many asthma phenotypes (the results of genes and the environment). Studies have found unique subgroups of asthmatics that may be more directly related to their obesity. These patients tend to be older, female, may not be respond as well to steroids, and have asthma less related to allergies.
By sharing and accepting the challenge of losing weight, and using objective data (like pulmonary function testing) to guide care, clinicians can help improve their asthmatic patients' quality of life. Obese asthmatic patients need help understanding what is causing their shortness of breath and the best ways to feel better (using their rescue inhaler may not be it). We are all obesity caregivers whether we realize it or not, and can all help improve their lives.
Learn More about Obesity and Weight Management