How Obesity Affects Asthma and Sleep Apneaby Sue Mittenthal
Excess weight makes breathing more difficult for most people, and that may be especially true if you have asthma or sleep apnea.
Ample evidence suggests a connection between packing on pounds and asthma risk as well as asthma control. Too much weight can also blunt the effects of certain asthma medications. In addition, obesity is a major risk factor for obstructive sleep apnea, a disorder that can lead to serious health problems.
To make matters worse, the United States has been in the midst of an obesity epidemic for the past three decades, and it doesn’t show signs of abating. More than a third of American adults are obese, including 40 percent of women and 35 percent of men, according to a 2016 analysis based on a large national health survey published in the Journal of the American Medical Association.
It’s not surprising then that the number of people with asthma or sleep apnea has increased as well. Fortunately, a growing body of evidence suggests that losing weight can help ease breathing problems in people with those disorders.
Impact of obesity on asthma
Studies show that obesity is a risk factor for developing asthma and that the more extra weight a person carries, the greater the risk.
In a 2016 report from the U.S. National Center for Health Statistics, the link between weight gain and asthma was particularly strong among women and people age 60 or older. For instance, about twice as many women who were obese suffered from asthma compared with normal-weight women, the report found.
Evidence also indicates that obese people with asthma have worse symptoms, more limitations in daily activities, greater use of rescue medication, and a poorer response to some asthma control medications.
A 2016 study of more than 4,000 children showed that despite having normal measures of airflow, obese children were more likely to have large lungs and thus have relatively low airflow rates for lung size. This “size-flow” mismatch was associated with increased likelihood of severe asthma flares, use of steroids, and worse outcomes in these obese children over time. The research was published in the American Journal of Respiratory and Critical Care Medicine.
Similarly, in adults, more than 50 percent of adults with severe or difficult-to-treat asthma are obese, according to a 2014 study in the Journal of Allergy and Clinical Immunology. Poorly controlled asthma can lead to serious asthma attacks. Excess weight is associated with that risk as well.
In a 2015 study, published in the Journal of Allergy and Clinical Immunology, researchers analyzed the medical records of more than 10,000 people with persistent asthma who were enrolled in a large managed-care organization in California. Patients who were overweight or obese were 40 percent more likely than their normal-weight counterparts to have an asthma attack that resulted in an emergency room visit or hospital stay.
Obesity and sleep apnea
Obesity is the most important risk factor for obstructive sleep apnea; in fact, at least two out of three sleep apnea patients are obese. Researchers believe this is at least partly due to excess fat stored around the neck in overweight people. The extra fat narrows the airway, making it more likely to close repeatedly during sleep.
But abdominal obesity in particular appears to be a key player in sleep apnea, especially for men, who are more likely than women to have the sleep disorder.
Researchers in Japan explored the relationship between excess belly fat and sleep apnea in men and women in a 2014 study published in Annals of the American Thoracic Society. They found a strong link between sleep apnea and excessive belly fat in men, but not in women. Men also had a larger amount of abdominal fat and more severe sleep apnea than women, despite similar body mass index (BMI).
Excess belly fat may worsen lung function by pushing on the diaphragm and chest wall, making it harder for the lungs to expand and fill with air. Compared with men, women store more fat below the waist, in the hips and thighs.
Sleep apnea itself can promote weight gain, which in turn worsens the sleep disorder, creating a vicious cycle. People with sleep apnea don’t sleep well and may be too tired during the day to exercise. That decreases the number of calories they burn. At the same time, poor sleep can disturb the balance of hormones that control appetite, resulting in hunger and overeating.
Losing weight helps
Research shows that if you are overweight or obese and have asthma or sleep apnea, weight loss can improve your lung function and reduce your symptoms. Plus, losing extra pounds has many other health benefits and is strongly recommended in professional treatment guidelines for asthma and sleep apnea. Here’s what the evidence shows for each condition.
In a small 2015 study of obese adults with asthma, published in the journal Chest, researchers in Canada compared 16 participants who followed a low-calorie diet and increased their physical activity with six control subjects. The group that dieted achieved an average weight loss of 14 percent that led to significant improvements in asthma severity (measured by airway sensitivity), asthma control, lung function, and quality of life. The control group, in contrast, showed no such improvement. Note that this study involved only 16 people; further research is required to confirm these results.
Another 2015 study, published in Annals of the American Thoracic Society, randomly assigned 330 obese adults with uncontrolled asthma to a diet and exercise program or a control group. A weight loss of 10 percent or more was associated with meaningful improvement in asthma control.
Other research has shown that bariatric surgery, which is an option only for obese individuals (BMI of 40 or more or a BMI of 35 or more with obesity-related medical problems), leads to improvements in asthma as well.
• Obstructive sleep apnea
Evidence indicates that a moderate reduction in weight can prevent sleep apnea from getting worse or even cure it, particularly in early stages of the disease.
In a 2014 study published in the journal Sleep Medicine, Finnish researchers tracked 57 obese people with mild sleep apnea who either underwent a supervised program of diet and exercise or were given general information about those topics. The participants were followed for five years.
Those who sustained a weight loss of 5 percent or more—considered the successful group—saw significant long-term improvements in sleep apnea, including an 80 percent reduced risk of progression of their condition. What’s more, the mild sleep apnea was cured in 50 percent of the successful participants.
Other studies show that bariatric surgery can result in major weight loss and significantly reduce the severity of sleep apnea, or cure it, in a small number of patients.
• Weight-loss tips
Weight-loss strategies for people with lung disease are generally the same as for everyone: Burn more calories than you consume. A reasonable and safe approach is to try to lose 1 to 2 pounds per week.
To achieve that, you’ll need to reduce your food intake by 500 to 1,000 calories a day. If you need help making healthy choices, ask your doctor to refer you to a registered dietitian, who can prepare a personalized food plan.
One of the best ways to keep weight off is to burn off some of those excess calories with regular physical activity. But that can be a challenge, since both asthma and obesity can increase breathlessness.
Walking is often a good way for people with lung disease to get moving, and it puts minimal stress on the joints, an important consideration for obese people. But talk to your doctor before you start any exercise program.