Obesity and shortness of breath: why you get out of breath, and how weight loss helps

Can obesity cause shortness of breath? The short answer

Yes. Carrying a lot of extra weight, especially around your middle, changes how your lungs and chest wall move, so breathing takes more effort and you run out of air sooner when you walk, climb stairs or carry shopping.

The American Lung Association lists obesity among the everyday reasons why breathing can feel hard, alongside heavy exercise, very hot or cold air and high altitude. In other words, getting puffed on the stairs is a common, expected effect of a heavier body. It is not a sign of weakness.

The good news is that this kind of breathlessness often improves. As your fitness grows and your weight comes down, the same stairs and the same walk can start to feel lighter over the weeks and months.

There is one important exception. Breathlessness can also come from the heart, the lungs, the blood or anxiety, and some of those causes need treatment. So if your breathing has changed, feels worse than you would expect, or comes with other symptoms, get it checked before you assume it is only your weight.

Why do you get out of breath so easily when walking or climbing stairs?

You get out of breath quickly because several things add up at once: your lungs have less room, your breathing muscles work harder, and your body needs more oxygen to move a heavier frame.

Less room for the lungs

Fat stored inside the belly and around the chest pushes up against the diaphragm, the dome-shaped muscle under your lungs, and stiffens the chest wall. A review by Dixon and Peters explains that this lowers the amount of air left in your lungs after a normal breath out.

That resting lung volume fell by up to about 10% in people who were overweight, 22% in mild obesity and 33% in severe obesity. With less air in reserve, small airways close more easily and breathing feels tight sooner.

The same review notes that lung function is linked more closely to waist size than to BMI. Fat around the middle matters most, which is one more reason to look at belly fat and not only at the scale.

More work for every breath

Because the chest and belly are heavier, your breathing muscles have to lift more with every breath. Researchers who study breathlessness in obesity point to a higher oxygen cost of breathing: part of the oxygen you take in is used just to keep the breathing going.

Lying flat can make this worse, because the belly then presses even harder on the diaphragm. Many people sleep better propped up for that reason, but needing to sit up to breathe at night is something to mention to your doctor.

Lower fitness and a busy heart

Walking with a heavier body simply takes more energy, so your heart and lungs reach their limit earlier. If you have not been active for a while, your muscles also use oxygen less efficiently, and that makes you breathe harder at a lower pace.

This part responds well to training. Regular walking makes your heart and muscles more efficient, so you breathe less hard at the same speed, even before your weight changes much.

Normal breathlessness during exercise vs warning signs

Breathing faster and deeper while you walk, climb or carry something is normal, as long as it settles within a few minutes of slowing down or resting. Breathlessness that comes on suddenly, happens at rest or comes with other symptoms is not normal and needs medical help.

The American Lung Association advises treating shortness of breath with chest pain or pressure, fainting or nausea as a medical emergency. It also lists dizziness, turning blue, trouble breathing when lying down or sleeping, and swelling in the feet and ankles, together with breathlessness, as signs that need immediate medical care.

Call your local emergency number straight away if you are short of breath with chest pain, pressure or tightness, if your lips or face turn blue or grey, if you faint or nearly faint, if breathlessness comes on suddenly and does not settle with rest, or if you cannot speak in full sentences.

If you have asthma and your reliever inhaler is not helping, or you find it hard to walk or talk, follow your asthma action plan and call for an ambulance.

The American Lung Association also says not to accept breathlessness without knowing why. If you are unsure, it is always fine to ask. Our doctor visit checklist helps you prepare questions, such as when it started, what brings it on and what makes it better.

Anxiety and panic can cause a feeling of air hunger as well, and being breathless can in turn make you anxious. Our page on sleep, stress and mental health covers that side; just do not assume anxiety is the cause until a doctor has checked.

Obesity hypoventilation syndrome (OHS): what it is and who gets it

Obesity hypoventilation syndrome means that a person living with obesity does not breathe deeply or often enough, so too little oxygen gets in and too much carbon dioxide stays in the blood, not only at night but also while awake. It is also called Pickwickian syndrome, after a sleepy character in a Charles Dickens novel.

The American Thoracic Society (ATS) defines OHS as the combination of three things: a BMI of 30 or more, a sleep-related breathing problem, and a raised carbon dioxide level in the blood during the day, once other causes have been ruled out. Doctors look for an awake carbon dioxide pressure of 45 mmHg or more in a blood sample.

Symptoms of OHS

The ATS patient information lists sleepiness, lack of energy, breathlessness, headache and low mood during the day. At night, there may be loud, frequent snoring and pauses in breathing that a bed partner notices.

Many of these symptoms overlap with ordinary tiredness, which is one reason OHS is often missed. Over time, too little oxygen can put a strain on the heart, so breathlessness together with swollen ankles always deserves a check.

Who gets OHS?

Severe obesity is the main risk factor. How common OHS is in the general population is unknown, but studies found it in about 8% to 20% of people with obesity who were sent to a sleep clinic for possible sleep-related breathing problems.

OHS matters because, left untreated, it raises the risk of heart failure, high blood pressure in the lungs, hospital stays and early death, according to the ATS guideline. The encouraging part is that it can be treated, and treatment often makes people feel far more awake.

How OHS differs from obstructive sleep apnea

About 90% of people with OHS also have obstructive sleep apnea, and roughly 70% have a severe form, so the two often travel together.

But they are not the same: sleep apnea is about the throat closing during sleep, while OHS means carbon dioxide stays too high even in the daytime. Everything about sleep apnea itself, including snoring, sleep tests, CPAP and how weight loss helps, is on our page about sleep apnea and weight loss.

How OHS is diagnosed and treated

OHS is diagnosed with blood tests that show your carbon dioxide level, together with a sleep study that shows what your breathing does at night. Treatment usually combines a breathing machine during sleep with a long-term plan to lose weight.

Tests your doctor may use

• A simple blood test for bicarbonate. When the chance of OHS seems low to moderate, the ATS suggests using this ordinary blood test first: a level below 27 mmol/L makes OHS very unlikely.
• An arterial blood gas. If OHS is strongly suspected or bicarbonate is raised, a small blood sample is taken from an artery, usually at the wrist, to measure carbon dioxide and oxygen.
• A finger oximeter. This clip estimates oxygen, but not carbon dioxide, so it cannot diagnose OHS on its own.
• A sleep study. It shows whether sleep apnea is present and how severe it is, and is used to set the right treatment pressure.
• Other checks. A chest X-ray and lung function tests may be done to rule out other causes of breathing difficulty.

Treatment options

For stable people with OHS, the ATS guideline suggests positive airway pressure (PAP) during sleep. This is a machine that blows air through a mask while you sleep or nap.

There are two main types. CPAP gives one steady pressure; non-invasive ventilation (NIV), usually a bilevel device, gives more pressure as you breathe in than as you breathe out.

For most people who also have severe sleep apnea, the ATS suggests starting with CPAP. For someone leaving hospital after a breathing crisis, the ATS suggests going home with NIV until further tests are done.

According to the ATS patient information, no medicines are currently recommended to treat OHS itself. Weight loss is the other main pillar of treatment, and the next section looks at how much it takes. Your specialist decides which device and settings fit you; we do not recommend any make or model.

How much weight loss helps OHS? What the studies show

The ATS guideline suggests that people with OHS aim for a sustained weight loss of 25% to 30% of their body weight, because that is the amount most likely to make OHS go away. For someone weighing 140 kg, that is about 35 to 42 kg.

That target sounds large, and it is. You can work out your own numbers with our weight loss percentage calculator. The panel itself called this a conditional recommendation based on very low-quality evidence, because only a handful of small studies exist.

The systematic review behind the guideline, by Kakazu and colleagues, found six studies with 16 to 63 people each. Lifestyle programmes with counselling, diet and exercise led to 6% to 7% weight loss, which on its own did not clearly change OHS compared with usual care.

Bariatric surgery led to much larger weight loss (15% to about 65%, depending on the operation), less severe sleep apnea, lower carbon dioxide levels and, in many people, OHS going away. About one in five people had side effects after surgery, though serious ones were very rare.

What does this mean for you? Lifestyle change is still the base: it lowers weight, improves fitness and helps with blood pressure, blood sugar and mood. But with OHS, keep using your breathing machine while you lose weight, and let your specialist decide when anything changes.

Surgery and medicines are options to discuss with your own doctor or specialist; see our pages on bariatric surgery and obesity medication for neutral information. Whether medication is right for you is something to discuss with your doctor. Obesity Foundation does not recommend or promote weight-loss medication; our focus is good food, appropriate exercise and walking.

Obesity and asthma: can extra weight cause or worsen asthma?

Extra weight raises the chance of developing asthma and tends to make existing asthma harder to control. Losing weight can improve asthma, especially when the loss reaches about 10% of body weight.

Can obesity cause asthma?

A meta-analysis of 16 cohort studies with more than a million adults found that every 5-point rise in BMI went with about a 32% higher risk of developing asthma. Each extra 10 cm around the waist went with about a 26% higher risk, and gaining 10 kg with about a 33% higher risk.

This shows a link, not proof that weight is the only cause. A review by Peters, Dixon and Forno describes obesity as both a major risk factor and a disease modifier for asthma, with mechanical, inflammatory and metabolic effects all playing a part.

Some people with obesity have asthma that started in childhood and is linked to allergies. Others develop it as adults, often with little allergy, and their symptoms seem to be driven more by the weight itself. In one study, a sensitive-airway measure improved after weight loss only in this second group.

Why asthma is often harder to control with extra weight

According to the same review, adults with obesity and asthma tend to have more symptoms, more frequent flare-ups and a lower quality of life. Their risk of being admitted to hospital for asthma was four to six times higher than in lean adults, and some asthma medicines work less well for them.

The squeezed lungs described above can also cause wheeze and breathlessness that feel like asthma. That is why a proper diagnosis with lung function tests matters, so you get treatment for the problem you really have.

Does weight loss improve asthma?

An older Cochrane review found only four small trials and could not draw firm conclusions. Newer reviews are clearer. A meta-analysis of 12 randomised trials with 1,052 people found that weight loss improved asthma control scores and lung function.

A second meta-analysis, of six trials with 522 adults, found that 12 to 24 weeks of weight loss improved asthma control, quality of life and lung function. People who lost 10% or more of their weight had the biggest gains.

At the one-year check, the pooled benefit was no longer clear, which suggests that keeping the weight off matters as much as losing it.

The Peters review adds that a loss of at least 5% seemed to be needed before asthma control improved in adults. For someone weighing 120 kg, 5% is 6 kg and 10% is 12 kg.

Keep using your asthma medicines exactly as prescribed while you lose weight, and carry your reliever inhaler on every walk. Never stop or cut down an asthma treatment on your own; your doctor or asthma nurse can review it as your breathing improves.

Does weight loss improve breathing? What changes and how fast

For many people, yes: losing weight and moving more can make everyday breathing easier, and some notice it on the stairs within the first months. Better fitness may help even before the scale shows a big change.

In a small study by Bernhardt and Babb, 29 women with obesity followed a 12-week programme of diet and strength exercise and lost about 7 to 8 kg on average. Among the women who were breathless during exercise at the start, breathlessness scores dropped clearly, from about 4.7 to 3.1 on a 10-point scale.

Interestingly, the drop was not explained by any single measured change, such as lung volumes or the oxygen cost of breathing. The programme used diet and resistance exercise, without aerobic training. Because the study was small, it shows what is possible rather than what everyone will experience.

The review by Dixon and Peters describes how weight loss can increase lung volumes and improve airflow, especially the reserve of air you had lost.

Sleep can improve too, as night-time breathing problems ease, and better sleep makes it easier to stay active. If you use a breathing machine at night, keep using it until your doctor says otherwise.

Aim for steady, safe loss rather than a crash diet; our page on safe weight loss explains a sensible pace.

How to start walking when you get out of breath quickly

Start with short, slow walks that you can repeat, rest whenever you need to, and build up by a minute or two at a time. Breathlessness that settles quickly with rest is usually fine; your body is adapting.

Talk to your doctor first, especially if you have heart or lung problems, OHS, asthma or swollen legs. Then use these practical ideas as a starting point:

• Pick a pace you can talk at. You should be able to say a full sentence. Our talk test explains how to judge your effort without a watch.
• Split your walking. Two or three short walks a day are easier on your breathing than one long one. If even five minutes is a lot, our guide for when you can only walk a few minutes shows how to begin.
• Plan your rests. Stopping on a bench or leaning on a wall is part of the plan, not a failure. Slow down before you are gasping, not after.
• Try pursed-lip breathing. The American Lung Association teaches this to people with lung conditions: breathe in gently through your nose, then breathe out slowly through lips shaped as if blowing out a candle, taking about twice as long to breathe out. It slows your breathing and can calm you down.
• Take it easy on hills and stairs. Go one step at a time, pause on a landing, and breathe out on the effort.
• Keep your reliever with you if you have asthma, and avoid very cold air or traffic fumes if they set off your symptoms.

Our walking guide has more on shoes, chafing and breathlessness, and our page on adapting low impact cardio shows how to move at home when walking outside is still too much. Exercise in a warm pool, where the water supports your body, is another option; see swimming for weight loss.

If dancing appeals to you more, our page on dancing for weight loss shows gentle ways to start. Whatever you choose, the rule is the same: start small, stay at a talking pace and add a little each week.

An 8-week plan to breathe easier

This plan combines short walks, one small food change each week and a simple breathing check-in. Talk to your doctor first before you start, and adjust the minutes to your own body: repeat a week as often as you need.

Write your check-in results in a notebook or app. Seeing that you climb more stairs or rest less often is a powerful reason to keep going, even in a week when the scale does not move.

If the plan feels too easy, add a few minutes more or try the Start level of our free workouts. If it feels too hard, go back a week; there is no prize for speed. Stop and get help if you notice any of the warning signs listed above.

For the bigger picture of how weight affects your body, read about the health risks of obesity or start with what obesity is.

Free help to lose weight and breathe easier

We help people lose weight and get healthier with good food, suitable exercise and walking. All of it is free, and it is meant to sit next to the care you get from your own doctor, never to replace it.

• A free eating plan: filling meals that help you eat a little less without feeling hungry, so the kilos come off at a steady pace. Ask for your free eating plan.
• Free workout videos: 150 videos in three levels, starting with gentle, chair-based Start sessions you can do at your own breathing pace. Get the free videos.
• A free video meeting (in English): go through your first steps with a volunteer and prepare questions about your breathing for your doctor. Book your free video meeting.
• The free Obesity Foundation Club: log your walks, stairs and workouts and watch your progress grow. Join the Club.

Our volunteers are not doctors. Questions about blood tests, sleep studies, breathing machines or inhalers belong with your own doctor, nurse or specialist.

Getting out of breath on the stairs is a very common reason to want to change. With short walks, steady food changes and the right medical checks, breathing usually gets easier, one flight of stairs at a time.