Does Obesity Cause Asthma?
So much evidence links fat (adipose tissue) with asthma that some folks like to call it Fatsma. In fact, I was recently emailed this question: "What are your thoughts on "Fasthma" a.k.a. "Fat Asthma" or obesity related asthma?"
Truthfully, the link between obesity and asthma, and obesity and asthma severity, is so significant, that has lead some researchers to classify it as an asthma subtype called Obese Asthma. This diagnosis is significant because this subtype has unique causes requiring unique treatment options.
I recently wrote a post Can Eating High-Fat Foods Trigger Asthma? I wrote about a 2010 study that determined lung function was worse after eating a high-fat meal. One theory suggests that your asthmatic immune system might recognize saturated fat as an enemy and promptly act to rid it from your system.
This response results in an increase in markers of inflammation such as leukotrienes and hystamine, and these increase inflammation in your respiratory tract. This causes muscles lining your air passages to constrict, and thus an asthma attack is the result.
If you are exposed to something that's triggering the inflammatory response often enough, this inflammation may become permanant, resulting in chronic asthma.
Experts at the Harvard School of Public Health came up with two more theories why obesity may lead to asthma:
Hormones released from fat tissue
Breaths are shallower than normal due to fat tissue making less room for the lungs to expand. Full stomachs also put added pressure on the diaghragm, which further restricts the ability of the lungs to expand.
This shallow breathing increases the probability inflammation will exist in the air passages of the lungs, and this causes the airways to become chronically narrow. This in and of itself may cause shortness of breath. This chronic inflammation also makes the airways oversensitive to asthma triggers.
Inflammation in of air passages is also believed to be caused by hormones, such as leptin, released from fat tissue. Leptin is present in all asthmatics, but it is elevated in the obese.
Likewise, people that are obese are less likely to have a hormone called adiponectin, which is an anti-inflammatory hormone.
On the flipside, inactivity due to asthma may cause obesity. Researchers at Kings College in London also discovered that Th2 cells, those cells responsible for causing airway inflammation, may also trigger the release of a protein called PMCH, which increases appetite.
In another post, Alright Asthmatics! Here's Your Incentive to Get in Shape This Year, I explained several studies that concluded that excissive adipose tissue may cause asthma. So it is possible that asthma may cause obesity.
Consider the following:
- A study completed by the Center for Disease Control and prevention showed that obese adults were 66 percent more likely than normal weight adults to have asthma.
- Experts at the University of South California performed a study showing obese children were 1.5 times more likely to be diagnosed with new onset asthma.
- Results from the National Health and Nutrition Examination Survey (2005-2006) showed that "Obese children were about 26 percent more likely to have allergies than children of normal weight". Allergies may also lead to asthma, and about 75% of asthmatics have allergies.
- Researchers from Kaiser Permanente, Massachusetts General Hospital and Harvard Medical School, learned that obese asthmatics are five times more likely to be hospitalized for asthma, have a lower quality of life, and have worse asthma control as compared to those with asthma at a normal weight.
- According to a study released in 2007 by researchers at Emory Crawford Long Hospital, obese asthmatics are more likely to have persistent or severe asthma.
- This 2005 study by experts at the Harvard School of Public Health notes that 75 percent of emergency room visits are among asthmatics that are obese.
- Researchers also found obesity to make asthma medicines work less well, and in some cases require higher doses than normally recommended.
Recognizing that a person has asthma, and then further recognizing a person has Obese Asthma, can help a physician better monitoir and treat these patients. Treatment may involve a diet and exercise program, it may also involve aggressive treatment with medicine.
Obese asthmatics who develope severe or medicine resistant asthma may require aggressive treatment with alternative treatment options. There are many options, although finding the best ones may be a matter of trial and error, and may take time.
Working with an asthma doctor, and compliance with whatever treatment regime is decided upon, is essential to obtaining good asthma control.
Surely a sedentary life from a lifetime of hardluck asthma may cause obesity. Yet the evidence appears to be overwhelming that obesity may cause asthma too. With the rising obesity rates of late, this is surely something to be concerned about.
Regardless, the link between obesity and asthma is all the more reason to eat a healthy diet and exercise -- especially if you have asthma.