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Obesity and Respiratory Disorders

By Dr Ananya Mandal, MD

Obesity is one of the most important causes of several chronic disorders and health conditions including heart disease, diabetes, liver disease and some cancers. It is defined as a body mass index (BMI) greater than 30 kg/m2.

Estimates suggest that over 1.6 billion adults worldwide are overweight, of which around 300 million are obese. According to the estimates of the World Health Organization, 10% of the global population will be obese by 2015.

In the European countries the numbers of obese individuals has tripled over the past 2 decades and in the United States nearly a third of all individuals are obese or overweight. In the UK obesity contributes to 30,000 deaths a year and £3.5 billion (US $5.4 billion) in health care costs and in the USA the annual health care costs are 36% greater for an obese person compared to a normal weight person.

Why do respiratory problems occur with obesity?

With the rise of weight and BMI the lung volumes decreases. This leads to more restricted air entry. There is lowered:-

  • forced expiratory volume in 1 second (FEV1)
  • forced vital capacity (FVC)
  • functional residual capacity (FRC)
  • expiratory reserve volume (ERV)
  • residual volume (RV)
  • total lung capacity (TLC)

Fat distribution and respiratory problems

Obesity around the abdomen further leads to worsening lung function and respiratory symptoms. Lower body fat deposition is less associated with respiratory symptoms in comparison.

It is hypothesized that deposition of fat tissue in the abdominal wall and around the abdominal organs hampers movement of the diaphragm and reduce the lung expansion during inspiration and reduced lung capacity.

The function of the respiratory muscles also deteriorates in obese patients much like in respiratory diseases like chronic obstructive lung disease (COPD).

Obesity and the respiratory system diseases

Obesity affects the respiratory system health adversely in more ways than one. Some of the health effects of obesity on respiratory system include diseases like:-

  • Exertional dyspnea – This is basically severe breathlessness caused due to minor exertions. This is a common feature among obese individuals.
  • Obstructive sleep apnea syndrome – This condition leads to closing or narrowing of the airways during sleep leading to snoring, repeated waking and lack of adequate and restful sleep.
  • Chronic obstructive pulmonary disease (COPD)
  • Asthma – Obese patients are more at risk of asthma exacerbations. Studies show the prevalence of asthma is higher by 38% in overweight patients and by 92% in obese patients. Obese patients with asthma also get more acute attacks, need more asthma medication, need more frequent visits to the emergency department (ED), and have more hospital admissions than non obese patients with asthma.
  • Obesity hypoventilation syndrome – Obese individuals have low lung reserve and may thus have difficulty in providing enough oxygen for their body. This may lead to hypoxia or low oxygenation of the body.
  • Pulmonary embolism – This is a serious condition where a blood clot gets lodged in the blood vessels of the lungs leading to a life threatening medical emergency. Pulmonary embolism may lead to failure and death.
  • Aspiration pneumonia – Due to the short and narrowed airways there is a possibility of the stomach contents moving into the lungs. This causes severe pneumonia caused by the harmful stomach acids.

Reviewed by , BA Hons (Cantab)

Further Reading

Last Updated: Apr 8, 2013

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