Obesity and asthma
It is very important that you maintain an ideal weight and good physical fitness if you have asthma. Being overweight may certainly make breathing more difficult, and some people find that their ability to breathe is worsened by the feeling of being full. It is also postulated that being overweight encourages gastro-oesophageal reflux disease (GORD), which can be a trigger for asthma in some people.
While there appears to be much evidence that being obese is a risk factor for developing asthma, there is also some evidence to the contrary.
Results of a Harvard Medical School study, published in the Archives of Internal Medicine in November 1999, showed that obese people (measured by body mass index [BMI]) are more likely to develop asthma than non-obese people. The risk of asthma increased with increasing BMI, being as much as 2.7 times more likely. The study, led by Dr Carlos A. Camargo Jr, involved 85,911 female American registered nurses.
Although the study did not reveal exactly how the risk of asthma is increased by obesity, Dr Camargo speculates that it may be because excess weight compresses the airways, making them smaller and more reactive to cold and other asthma triggers.
Conversely, an Australian study of nearly 2000 adults found that although adults with severe obesity had more wheeze and shortness of breath — which may suggest a diagnosis of asthma — they did not have an increased rate of airway responsiveness, or obstruction, which are measures used in the diagnosis of asthma.
The underweight group in the study had increased symptoms of shortness of breath, increased airway responsiveness and reduced lung function but without an increase in asthma medication use.
In 2003, a broad-ranging review of existing medical literature concerning evidence both for and against an association between obesity and asthma concluded that evidence of a link between the 2 conditions is strong, although it is unlikely that one condition is directly causing the other.
This review proposed 3 possible explanations for the asthma—obesity association that require further investigation to verify:
- that GORD as a result of obesity causes asthma;
- that physical inactivity promotes both obesity and asthma; and
- that the diets of obese people may potentiate asthma.
Food and drink and your asthma
Food and drink are not common asthma triggers and there are no special diets for people with asthma. Asthma attacks triggered by food occur in less than 2 per cent of adults and 11 per cent of children with asthma. Diets for people with asthma are required only when a specific food or additive sensitivity has been found, so you probably won’t have to give up any foods unless you are proven to be allergic to them.
Staying fit and healthy is important for controlling your asthma. You should eat a healthy and balanced diet that includes a variety of nutritious foods from all the food groups. Moderate the amount of fat in your diet and limit the amount of saturated fat, which includes animal fats such as butter and visible fat on meat.
Exercise and your asthma
Exercise and daily physical activity can help you lose weight, maintain good health and fitness and control your asthma. Being active will also help strengthen your lungs, heart and muscles.
You should be able to exercise without the symptoms of asthma appearing if your asthma is well managed. Exercise that includes a lot of stopping and starting or takes place in a warm, moist environment is less likely to cause exercise-induced asthma (EIA). Walking, swimming, tennis, yoga, aerobics and martial arts are recommended for people with asthma, while running and cycling are the most difficult activities for people with EIA.
If you find that you can’t exercise without triggering your asthma, talk to your doctor about tailoring an exercise and medication programme to your needs.
Last Reviewed: 03 November 2003
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