Understanding sleep apnoea and obesity | ResMed UK

Like many things in life, the relationship between obesity and sleep apnoea is not completely straightforward. In fact, you could say they have a two-way relationship. What do we mean? Well, while there’s evidence that suggests losing weight can reduce the severity of sleep apnoea1, some studies also suggest that treating sleep apnoea can help with weight management2. What’s more, it’s perfectly possible to have sleep apnoea without being overweight – in fact, people of all shapes and sizes can have the condition.
Feeling confused? We’re here to help clarify things. Let’s start by looking at the numbers…

Statistics on obesity and sleep apnoea

Obesity is commonly defined via the body mass index (BMI). An adult’s BMI is calculated by dividing their weight in kilograms by their height in metres squared. The resulting figure can then be put into the following categories:

  • Underweight: 18.5 and below
  • Healthy weight: between 18.5 and 24.9
  • Overweight: between 25 and 29.9
  • Obesity: between 30 and 39.9
  • Severe (also known as morbid) obesity: 40 or more

Do remember that body mass index is just one measure of health – for example if you have a lot of muscle (which weighs more than fat) you may fall into the overweight category despite not having much body fat. BMI ranges can also vary slightly for people of different ethnic backgrounds and are measured differently in children, so it’s a good idea to speak to your doctor if you’re concerned about your weight. They may use other measurements, such as waist circumference, to help determine whether you need to lose weight.


How common is obesity or being overweight?

Throughout the world, almost 10% of adults are living with obesity – that’s almost one in 103 of the general population. And when it comes to the overweight category, the figures are even higher, with nearly one out of three3 adults having a body mass index between 25 and 29.9. So if you are carrying more weight than you’d like, you’re certainly not alone.


How common is sleep apnoea in people who are overweight?

The occurrence of sleep apnoea in the general population is thought to be around 25%4 – however, it’s estimated that more than 80% of sleep apnoea cases worldwide are yet to be diagnosed5, so it’s hard to pinpoint exact figures!

What we do know is that around 40% of people who are in the overweight category have sleep apnoea6. While this figure seems high, it’s worth bearing in mind that suggests 60% of overweight people don’t have sleep apnoea! In people with severe obesity, the percentage affected by sleep apnoea rises to 776. To understand why a higher body weight seems to be a risk factor for sleep apnoea, it helps to know the causes of the condition…

What causes sleep aponea?

The most common form of sleep apnoea is obstructive sleep apnoea (OSA)7. The word obstructive is key, as this type of sleep disorder occurs when the upper airways (in your nose and throat) get obstructed, or blocked, while you sleep, often creating a loud snoring sound. When this happens your breathing may stop for periods of 10 seconds or longer, which are called apnoeas. These apnoeas cause you to wake up briefly to gasp for air, before going back to sleep. This can happen hundreds of times a night, although you might not realise it… What you probably will notice are symptoms such as feeling tired in the morning, and having excessive daytime sleepiness even after a full night in bed.

Other common symptoms of OSA include:

  • Memory problems
  • Morning headaches
  • Feeling depressed or low in mood8
  • Night sweats9
  • Decreased libido10
  • Needing to wee frequently at night11
  • and finally… weight gain12


Does sleep apnoea cause weight gain?

As hinted above, weight gain can be one of the symptoms of OSA. This may be for a couple of reasons. Firstly, if you’re feeling exhausted due to a shorter sleep duration than you’d like it’s unlikely you’re going to have much energy or desire for exercise. Lack of good quality sleep can also disrupt levels of certain hormones in the body – including those that control appetite – so going without enough rest could make you want to eat more. And, of course, when we’re tired or feeling low we’re more likely to reach for sugary snacks and comfort food to give us a boost.

How does obesity affect sleep apnoea?

With obstructive sleep apnoea it’s all connected to what is blocking the airways. In most cases it’s the muscles and soft tissues of the throat, which relax during sleep. If someone has nasal congestion, a naturally more narrow airway or other physical characteristics13, such as a big tongue or large tonsils, the airway is likely to get blocked more easily. It’s not hard to see how being overweight or obesity could exacerbate this further: when people gain weight, they gain it all over – including visceral or ‘hidden’ fat deposits within the throat area. This additional body fat can narrow the airways, particularly if you’re lying down. People who are overweight are also more likely to have a bigger neck circumference13, which is another risk factor for OSA.

Weight can also affect the severity of OSA, which is split into three categories:

  • Mild: 5 to 14 apnoeas per hour
  • Moderate: 15 to 30 apnoeas per hour
  • Severe: more than 30 apnoeas per hour

As a general rule, the higher your BMI the more severe the sleep apnoea. If you have a BMI below 30, OSA is usually less severe – however these people still need attention, as they are four times more likely to develop high blood pressure than people in the obese category who don’t have OSA (see below for more on high blood pressure and OSA)14.


Mixed or central sleep apnoea and obesity

It’s worth noting that while obstructive sleep apnoea makes up 84% of sleep apnoea cases15, there are other forms that are less common:

  • Central sleep apnoea: this occurs when the brain stops sending signals to the muscles that control breathing during sleep, so breathing stops for short periods. It doesn’t have anything to do with the airways being blocked – they remain open during sleep.
  • Mixed sleep apnoea: as the name suggests, this is a combination of central and obstructive sleep apnoea.

Both these conditions are primarily caused by medical conditions affecting the brain, so aren’t associated with obesity.

Is obesity the only risk factor for sleep apnoea?

While we’ve seen that obesity is a risk factor for OSA, it’s certainly not the only one – which may help explain why people who are not overweight can also have the condition. Other risk factors include:

  • Being male16
  • Having a family history of sleep apnoea17
  • Advancing age (particularly over 55 years)18
  • Taking certain sedatives19
  • Drinking alcohol20 (particularly before bed)
  • Smoking21


Women and sleep apnoea

Although being male is a risk factor for sleep apnoea, some studies suggest that as many as half of women aged between 20 and 70 may have the condition22. And just as with men, weight can play a part – in fact, weight gain is one of the sleep apnoea symptoms that seems to be more common in women than men23. In addition OSA is seen more often in post-menopausal women, which may be because after menopause women have a tendency to gain weight.

See our article for more on sleep apnoea in women.


Childhood obesity and sleep apnoea

OSA is not common in children, with the condition affecting only around 2% of the general population24. However, when it comes to children and adolescents who are classed as obese, it’s thought the proportion with OSA could be as high as 60%25. According to the World Health Organization, in 2016 more than 340 million children and adolescents aged five to 19 were overweight or living with obesity26.

See our article for more on childhood sleep apnoea.

Sleep apnoea and severe or ‘morbid’ obesity

As well as having a higher risk of developing OSA, people living with obesity and severe obesity are at risk of other breathing disorders too…


Obesity hypoventilation syndrome (OHS)

This condition is usually only seen in people with obesity or severe obesity. The risk of OHS rises with body mass index: almost half of people with a BMI of 50 or more have the condition27 (for context, it’s projected that by 2030 nearly one in four people in the United States will have a BMI of more than 5028).

OHS shares some of the same symptoms as OSA, such as daytime sleepiness and headaches, but can also cause difficulty breathing. Around 90% of OHS patients also have obstructive sleep apnoea3,29, and often have other conditions at the same time, such as cardiovascular disease, with up to 88% having hypertension3,30.

While OHS is a serious condition, there is treatment available, so if you think you may be at risk take a look at our obesity hypoventilation syndrome page and speak to your doctor.

What happens if sleep apnoea goes untreated?

If a person has OSA and doesn’t get diagnosed or treated, then the symptoms discussed above will continue to negatively impact their quality of life. But reducing symptoms is not the only benefit of treating sleep apnoea (although it’s a pretty welcome one!).

It’s also been shown that people with untreated OSA have a higher risk of health conditions such as:

  • Hypertension (high blood pressure)31
  • Cardiovascular disease, such as coronary heart disease or stroke32-34
  • Type II diabetes35

These also happen to be conditions that people living with obesity are more likely to experience, showing again how obesity and sleep apnoea are interrelated…


The connection between sleep apnoea, obesity and hypertension

Let’s take high blood pressure as an example. When someone has sleep apnoea, the repeated pauses in breathing and subsequent drops in oxygen supply they experience each night can place a strain on the body, which raises blood pressure. In addition, if a person is carrying excess weight, this can put a strain on the heart, causing it to work harder to get blood pumping, which again can lead to high blood pressure. This matters because persistent high blood pressure can increase the risk of serious conditions, such as cardiovascular disease – and so we’re back to the risks we mention above!

Treatment options for people living with obesity and sleep apnoea

Now we’ve looked at the negatives of sleep apnoea, here are some positives! There is lots that can be done help people with the conditions live happier, healthier lives. A treatment plan for someone with obesity and OSA might include a combination of the following:

  • Lifestyle changes, including weight management (which could also be aided by medication)
  • Continuous positive airway pressure (CPAP) therapy. This is considered the ‘gold standard’ treatment for OSA – more on this below!
  • A mandibular advancement device (a small oral appliance, like a gumshield, worn in the mouth overnight)
  • Surgery – in rare cases this may be considered if other treatments prove ineffective. It could take the form of either an operation to clear the airway of a physical blockage, or bariatric surgery (such as a gastric band or bypass) to aid weight loss.

Weight loss as a solution for sleep apnoea

Since OSA and obesity seem so closely linked, you might think the easiest solution to sleep apnoea is to lose weight. But it’s not quite as simple as that…


Is sleep apnoea reversible with weight loss?

From the evidence we have so far, it seems that while losing weight can help make sleep apnoea less severe, it rarely gets rid of it entirely – in fact there is no ‘cure’ for OSA, just ways of treating and managing the condition.


What happened to OSA patients who had bariatric surgery

The effect of weight loss on sleep apnoea was investigated in a review that followed up people with both obesity and OSA who had bariatric surgery to help them lose weight. The results showed that while the severity of sleep apnoea had decreased for many of the patients after bariatric surgery, only 65% of patients saw a remission of their OSA36. What’s more, most of the people who’d lost weight via bariatric surgery continued to have at least moderate OSA37.

Having said this, anything that makes OSA less severe is a good thing, particularly if you’re also having CPAP therapy (which you probably will be). That’s because of the way CPAP therapy works, which we’ll explain below…

What is CPAP therapy?

CPAP therapy is a common and effective treatment for OSA. CPAP stands for continuous positive airway pressure, this is because a CPAP machine produces a steady flow of pressurised air that a person breathes in via a mask while they sleep. This pressured air helps to keep the airways open, preventing apnoeas and hopefully leading to a more refreshing night’s sleep.

The amount of air pressure required to keep your airways open is somewhat dependent on how many apnoeas you have in a night (ie the severity of your OSA). Lower levels of pressure are easier to get accustomed to and more comfortable, so anything that helps reduce the severity of your OSA at the same time as having CPAP (like weight loss) is a good thing.

The benefits of treating OSA with CPAP therapy

Treating your OSA with CPAP therapy has benefits that are related to the reduction in sleep apnoea symptoms, such as a more positive mood38, more energy during the day39 (so you’re more likely to feel like exercising and keeping fit!), a clear mind38 and even a lower risk of road accidents40,41.

On top of this there are also benefits for your health – and in particular your cardiovascular health:

  • 64% reduction in risk of cardiovascular disease42 (compared to those who are not treated for OSA)
  • Lower blood pressure during the day and night43

Perhaps most striking of all, a recent analysis revealed that all-cause mortality (the total number of deaths in a group, regardless of what caused the deaths) was reduced in OSA patients who stuck to their therapy44.

Taking a combined approach to sleep disorders and obesity

You may be tempted to think that if you lost enough weight, you might be able to stop CPAP therapy altogether. However, while weight loss can help reduce the severity of OSA, it is unlikely to stop it completely (remember the results in people who’d had bariatric surgery?). So if you feel like your OSA symptoms have improved, it’s likely due to your weight loss in combination with the CPAP therapy – the two things are closely intertwined and it can be hard to tell what’s causing the other. For this reason, you should always speak to your doctor before stopping CPAP treatment. It’s likely they will encourage you to continue with a combined approach that benefits your whole health, rather than just your OSA.


Seeking help for obesity and OSA

Because of the connection between OSA and obesity, it’s recommended that people with a high BMI are tested for sleep apnoea. And as anyone can have the condition, no matter what their weight – if you’re experiencing any of the symptoms discussed in this article a good place to start is to take our free sleep assessment – this may help frame your conversation with your doctor. Good luck!



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  1. Hudgel DW, Patel SR, Ahasic AM, et al. The Role of Weight Management in the Treatment of Adult Obstructive Sleep Apnea. An Official American Thoracic Society Clinical Practice Guideline. Am J Respir Crit Care Med. 2018;198(6):e70-e87. doi:1164/rccm.201807-1326ST.
  2. Harsch, I A et al. Leptin and ghrelin levels in patients with obstructive sleep apnoea: effect of CPAP treatment. The European respiratory journal vol. 22,2 (2003): 251-7. doi:1183/09031936.03.00010103.
  3. Masa, Juan F et al. Obesity hypoventilation syndrome. European respiratory review : an official journal of the European Respiratory Society vol. 28,151 180097. 14 Mar. 2019, doi:1183/16000617.0097-2018.
  4. Young, T et al. The occurrence of sleep-disordered breathing among middle-aged adults. The New England journal of medicine vol. 328,17 (1993): 1230-5. doi:1056/NEJM199304293281704.
  1. Young, T et al. Estimation of the clinically diagnosed proportion of sleep apnea syndrome in middle-aged men and women. Sleep vol. 20,9 (1997): 705-6. doi:1093/sleep/20.9.705.
  2. Barness, Lewis A et al. Obesity: genetic, molecular, and environmental aspects. American journal of medical genetics. Part A vol. 143A,24 (2007): 3016-34. doi:1002/ajmg.a.32035.
  3. Muza, Rexford T. Central sleep apnoea-a clinical review. Journal of thoracic disease vol. 7,5 (2015): 930-7. doi:3978/j.issn.2072-1439.2015.04.45.
  4. Osman, Amal M et al. Obstructive sleep apnea: current perspectives. Nature and science of sleep vol. 10 21-34. 23 Jan. 2018, doi:2147/NSS.S124657.
  5. Arnardottir, Erna Sif et al. Nocturnal sweating–a common symptom of obstructive sleep apnoea: the Icelandic sleep apnoea cohort. BMJ open vol. 3,5 e002795. 14 May. 2013, doi:1136/bmjopen-2013-002795.
  6. Cho, Jae Wook, and Jeanne F Duffy. Sleep, Sleep Disorders, and Sexual Dysfunction. The world journal of men’s health vol. 37,3 (2019): 261-275. doi:5534/wjmh.180045.
  7. Ben Mansour, Amani, et al. Prevalence of nocturia in obstructive sleep apnea syndrome. European Respiratory Journal, 2015 46: PA2380; DOI: 1183/13993003.congress-2015.PA2380.
  8. Lyytikäinen, P et al. Sleep problems and major weight gain: a follow-up study. International journal of obesity (2005) vol. 35,1 (2011): 109-14. doi:1038/ijo.2010.113.
  9. Spicuzza, Lucia et al. Obstructive sleep apnoea syndrome and its management. Therapeutic advances in chronic disease vol. 6,5 (2015): 273-85. doi:1177/2040622315590318.
  10. Bixler, E O et al. Association of hypertension and sleep-disordered breathing. Archives of internal medicine vol. 160,15 (2000): 2289-95. doi:1001/archinte.160.15.2289.
  11. Morgenthaler, Timothy I et al. Complex sleep apnea syndrome: is it a unique clinical syndrome?. Sleep vol. 29,9 (2006): 1203-9. doi:1093/sleep/29.9.1203.
  12. Appleton, Sarah et al. Influence of Gender on Associations of Obstructive Sleep Apnea Symptoms with Chronic Conditions and Quality of Life. International journal of environmental research and public health vol. 15,5 930. 7 May. 2018, doi:3390/ijerph15050930.
  13. Casale, M et al. Obstructive sleep apnea syndrome: from phenotype to genetic basis. Current genomics vol. 10,2 (2009): 119-26. doi:2174/138920209787846998.
  14. Thompson, Cynthia et al. A portrait of obstructive sleep apnea risk factors in 27,210 middle-aged and older adults in the Canadian Longitudinal Study on Aging. Scientific reports vol. 12,1 5127. 24 Mar. 2022, doi:1038/s41598-022-08164-6.
  15. Deacon, Naomi L et al. Treatment of Obstructive Sleep Apnea. Prospects for Personalized Combined Modality Therapy. Annals of the American Thoracic Society vol. 13,1 (2016): 101-8. doi:1513/AnnalsATS.201508-537FR.
  16. Scanlan, M F et al.“Effect of moderate alcohol upon obstructive sleep apnoea. The European respiratory journal vol. 16,5 (2000): 909-13. doi:1183/09031936.00.16590900.
  17. Wetter, D W, and T B Young. The relation between cigarette smoking and sleep disturbance. Preventive medicine vol. 23,3 (1994): 328-34. doi:1006/pmed.1994.1046.