Breathlessness related to excess body weight may not be just a lack of fitness. Obesity and shortness of breath can indicate underlying inflammation and changes to your lung function.

Obesity is an excessive accumulation of body fat that increases your risk for adverse health effects and conditions like diabetes, cardiovascular disease, and hypertension.

One of the many symptoms associated with excess weight is breathlessness, also known as dyspnea. Though dyspnea can have many causes, a 2022 nationally representative Australian survey found obesity accounted for approximately 25% of all breathlessness symptoms.

When shortness of breath from obesity reaches a specific severity, it can be diagnosed as obesity hypoventilation syndrome (OHS).

Obesity can affect your lung function by direct restriction and through indirect physiological processes.

When you gain weight, it falls within two patterns: central obesity and peripheral obesity.

Central obesity is weight accumulation around the chest and abdomen, creating an “apple shape” body type. Peripheral obesity creates a “pear shape” body type because fat is deposited mainly around the hips, thighs, and limbs.

Shortness of breath in obesity is usually associated with central fat gain. Fat stored in your chest and abdomen can restrict your lungs’ ability to expand, even at rest. This can alter how you breathe regularly, creating a persistent shallow breathing pattern.

Also, obesity can cause the narrowing of your airways and, in extreme cases, complete airway closure.

Central obesity also significantly impacts physiological processes in the body linked to breathing challenges. It creates a chronic low-grade inflammation that can contribute to metabolic syndrome, hormone overproduction, and sleep-disordered breathing.

Symptoms of obesity hypoventilation syndrome

Obesity hypoventilation syndrome (OHS), or Pickwickian syndrome, is diagnosed when obesity is present and blood gas levels reach a specific threshold.

OHS is usually indicated if your arterial partial pressure of carbon dioxide (PaCO2) is greater than 45 mmHg.

What are blood gas levels?

Your blood gas levels indicate how well your lungs are functioning. PaCO2 levels that are too high, for example, can indicate your lungs are not expelling enough carbon dioxide.

PaCO2 acceptable ranges are 35mmHg to 45mmHg.

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OHS is diagnosed only when other respiratory, neuromuscular, or metabolic conditions can’t explain symptoms.

Symptoms include:

Not everyone with obesity and shortness of breath has OHS. Obesity can cause breathlessness even if it doesn’t meet OHS diagnostic criteria.

An OHS diagnosis requires specific criteria to be met. Part of that process involves ruling out other conditions that can create dyspnea.

Your doctor will discuss your symptoms with you and perform a physical exam. Your weight, height, body mass index (BMI), and head and waist measurements will be considered.

Lung tests can help indicate your lung function. You may need to have:

In addition to these lung performance assessments, diagnostic imaging can help rule out other conditions known to cause breathlessness.

These procedures include:

To ensure a correct diagnosis, your doctor may suggest further testing, such as:

When no other conditions can be linked to your symptoms, obesity has been confirmed, and your arterial gas levels are at a specific point, OHS can be diagnosed.

OHS and obesity-related dyspnea treatments focus on normalizing ventilation and reducing body weight.

A 2018 review on OHS indicates continuous positive airway pressure (CPAP) is the immediate treatment of choice for stable cases of obesity and shortness of breath. CPAP uses a respiratory mask to deliver consistent pressure into your airways, allowing your body to expel toxins and saturate oxygen levels properly.

CPAP is one of two positive airway pressure (PAP) therapies available. Your doctor may recommend bi-level positive airway pressure (BPAP) instead. BPAP is similar to CPAP but uses two levels of pressure rather than a consistent one.

PAP in either form is done regularly. You’ll be prescribed an at-home machine that may need to be used for hours at a time.

Supplemental oxygen therapy is recommended alongside CPAP treatment when your oxygen levels are severely depleted.

In some cases, if obesity and shortness of breath have progressed to complete airway closure, a tracheostomy may be needed to maintain your airway, particularly while you sleep.

Can losing weight help with shortness of breath?

When shortness of breath is obesity-related, reducing your weight is the primary way to improve your symptoms.

Multiple studies show that weight loss is associated with improving OHS symptoms. As weight is reduced, your carbon dioxide levels decrease and lung function improves.

Though any weight loss is positive, the target baseline loss to treat OHS is 25% to 30% of your body weight.

Consistently following a diet plan and exercise routine long enough to achieve this goal isn’t always sustainable for people. For this reason, bariatric surgery is often recommended. Bariatric surgery involves modifying the stomach or intestines to allow reduced food intake, decrease hunger, and increase the sense of fullness.

If you opt for the diet route, your doctor and a dietician can help you create a plan that reduces weight at a safe rate. Losing weight too quickly can have negative health impacts, even if you’re trying to manage a condition like OHS.

What medications can treat OHS?

No medications have been found to be effective for treating OHS.

Obesity and shortness of breath are closely linked. Excess weight gain can alter your lung function and contribute to a physiological process of inflammation that further hinders breathing.

When dyspnea related to obesity reaches a certain point, it can be diagnosed as obesity hypoventilation syndrome.

PAP therapies are first-line treatments while you start your weight-loss journey. Safe weight loss takes time, and during that time, PAP can help you breathe easier.