Clinical reviewObesity and obstructive sleep apnea – Clinical significance of weight loss
Introduction
Obesity has become a serious health concern in recent decades, leading to increased morbidity and mortality, in particular from cardiovascular diseases.1, 2 Obesity is also the most important risk factor for obstructive sleep apnea (OSA) and in fact, most OSA patients (at least two out of every three) are obese.*3, 4, *5 The co-existence of obesity and OSA has a complex and far more serious impact on the cardiovascular and metabolic sequelae than either of these conditions on their own. OSA as such, has been found to have an independent association with cardiovascular diseases, type 2 diabetes, metabolic syndrome, deterioration of an individual’s quality of life and working capacity, and increased mortality.*5, 6, 7, 8, 9, 10, 11, 12 The importance and the effectiveness of weight loss in treating OSA have been well-known for more than two decades. The majority of the earlier studies on weight reduction in OSA patients evaluated either the effects of low and very low calorie diet programs in moderately overweight patients or the effects of bariatric surgery upon weight and concurrent OSA in severely obese patients.13, 14, 15, 16, 17, 18, 19 These studies have lead to conclusions that weight loss could reduce the severity of OSA, but that it was not a curative treatment for most patients. However, although weight reduction is recommended in all clinical guidelines, until recently there has been a lack of well-executed randomized intervention studies on the effect of weight reduction upon OSA.20 In the first randomized study to be conducted, we demonstrated that a lifestyle intervention lasting one year including an early weight reduction program represented a feasible and curative treatment for the vast majority of overweight patients with mild OSA.21 These findings have been supported by two other recent randomized studies, one examining obese OSA patients with type 2 diabetes and the other in obese patients with severe OSA, including an observational follow-up phase.*22, *23, *24 Most importantly, although the results of these and earlier studies are encouraging, it is not known, whether these favorable changes can be sustained after the discontinuation of the intervention. The recent post-interventional follow-up of our randomized study demonstrated that a successful weight reduction with lifestyle intervention can maintain the improvements of OSA for at least one year after the actual termination of the intervention.25 In earlier reviews on OSA, virtually no attention has been paid to the weight reduction as a potential key treatment modality not only for OSA but also for related co-morbidities. Recently this topic has finally attracted attention because of well-designed intervention trials, which unequivocally highlight the potential of weight reduction in this condition. It should be noted that weight reduction, more physical activity and adopting a healthy diet may have a marked influence on the well-being and cardiovascular risk of the OSA patients due to their beneficial effects on many cardiovascular and metabolic risk factors, e.g., glucose metabolism.3 The aim of this review is to focus on the new information on the importance of weight loss in the treatment of OSA and its metabolic co-morbidities in overweight patients.
Section snippets
Epidemiology of obesity and OSA
Excess body weight is perhaps the greatest health burden throughout the world, affecting almost every aspect of life and representing a major challenge to medical practice. It has been estimated that globally 1.6 billion adults are overweight [body mass index (BMI) > 25 kg/m2] and 400 million are obese (BMI >30 kg/m2).26 In the U.S.A., one out of every three adults has categorized as being obese.27 In Europe, the trends are in the same direction, for example in Finland one out of every five adults
Pathophysiology and risk factors of OSA
OSA occurs when there are repetitive collapses of the upper airway during sleep causing an obstruction of breathing, reduction in airflow and oxygenation. For patients with OSA, these disturbed nocturnal breathing functions also result in recurrent arousals causing a significant fragmentation of their sleep. The pathophysiology of OSA is complex and most likely multifactorial, consisting of a combination of predisposing anatomical factors and impaired neuromuscular compensatory responses.
Clinical symptoms related to OSA
The recurrent upper airway obstruction and the resulting interruptions in breathing during sleep characterized by OSA, are manifested as loud snoring, pauses in breathing, and sleep fragmentation. Due to the sleep fragmentation, OSA is often accompanied by daytime symptoms; fatigue, lack of concentration, morning headache, impotence, deterioration of an individual’s quality of life and working capacity.8, 11, 31 The breathing pauses can be divided into apneas and hypopneas; there is a total
Obesity related pathophysiology of OSA
The association between obesity and OSA seems to be bi-directional; obesity itself increases the risk for OSA, but, on the other hand, OSA may also predispose the individual to weight gain*3, *5, *33 (Fig. 1). There is current evidence that systemic inflammatory mediators related to obesity and localization of excess adipose tissue, e.g., increased fat tissue in the neck may have additional effects also in pharyngeal neural and mechanical control mechanisms that mediate collapsibility and
Weight reduction in OSA
The importance and the effectiveness of weight loss in treating OSA have been recognized for more than 25 years.15 The majority of the weight reduction and OSA studies have evaluated either the effects of low and very low calorie diet (VLCD) programs in moderately overweight patients with OSA or the effects of bariatric surgery upon weight and concurrent OSA in severely obese patients.13, 14, 15, 16, 17, 18, 19 Overall, the average weight loss and improvement in AHI after dietary interventions
Metabolic syndrome and OSA
Metabolic syndrome is a cluster of risk factors, which alone or in different combinations increase the risk for type 2 diabetes, cardiovascular morbidity and mortality.64 A recent study also suggested that sleep disturbance co-aggregated with other components of the metabolic syndrome and could be the second most important determinant after obesity.65 There are several reports that OSA is also associated with the metabolic syndrome and type 2 diabetes.7, 10, 31, *33, 65, 66, 67 In clinical
Cardiovascular consequences of obesity and OSA
OSA has been frequently been linked with cardiovascular diseases. The exact underlying mechanisms explaining the association between cardiovascular morbidity and OSA are not fully understood, although a multifactorial etiology is most likely.71, 72 Even mild OSA is associated with increased activation of the inflammatory system and a risk for cardiovascular morbidity, although the risk is more frequently associated with more severe degrees of the disease.73, 74 On the other hand, what was
Importance of weight loss – comeback of an abandoned cure
The improvement of OSA is highly associated with weight loss, and treatment results are comparable to those achieved by weight reduction in other obesity related morbidities. Table 3 summarizes the large body of evidence favoring lifestyle modification in the prevention and treatment of all obese related conditions. Weight reduction has been shown to result in a marked improvement in insulin resistance, and in some studies in type 2 diabetics also recovery of normal insulin secretion has been
Conclusion
Based on the current knowledge, weight reduction is a very effective treatment modality in overweight patients with OSA, and therefore, it should always be included in the treatment of OSA when this is linked to excess weight. In addition to improving OSA, weight reduction also improves the other obesity related disturbances of metabolic syndrome, e.g., the increased risk for cardiovascular diseases and type 2 diabetes. The cornerstone of treatment of overweight patients must be weight
Conflict of interest statement
We declare that we have no conflicts of interest.
Acknowledgments
Juho Vainio Foundation, Paavo Nurmi Foundation, Finnish Anti-Tuberculosis Foundation and the Research Foundation of the Pulmonary Diseases have supported the work with grants. The funding sources had no role in interpretation of the literature or writing of the report. The authors had final responsibility to submit the report for publication.
References* (91)
- et al.
Obesity and cardiovascular disease: risk factor, paradox, and impact of weight loss
J Am Coll Cardiol
(2009) - et al.
Prevalence of symptoms and risk of sleep apnea in the US population. Result from the National Sleep Foundation Sleep in America 2005 Poll
Chest
(2006) - et al.
Daytime sleepiness and cardiovascular morbidity at seven-year follow-up in obstructive sleep apnea patients
Chest
(1990) - et al.
Effect of very-low-calorie diets with weight loss on obstructive sleep apnea
Am J Clin Nutr
(1992) - et al.
A cognitive-behavioral weight reduction program in the treatment of obstructive sleep apnea syndrome with or without initial nasal CPAP: a randomized study
Sleep Med
(2004) - et al.
Adult obstructive sleep apnea: pathophysiology and diagnosis
Chest
(2007) - et al.
Are we really active in the prevention of obesity and type 2 diabetes at the community level?
Nutr Metab Cardiovasc Dis
(2011) - et al.
Weight loss as a treatment for obstructive sleep apnoea
Sleep Med Rev
(2000) - et al.
Sustained reduction in the incidence of type 2 diabetes by lifestyle intervention: follow-up of the Finnish Diabetes Prevention Study
Lancet
(2006) - et al.
Effects of surgical weight loss on measures of obstructive sleep apnea: a meta-analysis
Am J Med
(2009)
Obstructive sleep apnea and type 2 diabetes: interacting epidemics
Chest
Role of visceral adipose tissue in aging
Biochem Biophys Acta
Long-term cardiovascular outcomes in men with obstructive sleep apnoea-hypopnoea with or without treatment with continuous positive airway pressure: an observational study
Lancet
Sleep apnea after 1 year domiciliary nasal-continuous positive airway pressure and attempted weight reduction. Potential for weaning from continuous positive airway pressure
Chest
Long-term effects of gastric surgery for treating respiratory insufficiency of obesity
Am J Clin Nutr
Bariatric surgery in morbidly obese sleep-apnea patients: short- and long-term follow-up
Am J Clin Nutr
The effect of weight loss on sleep-disordered breathing and oxygen desaturation in morbidly obese men
Chest
General and abdominal adiposity and risk of death in Europe
N Engl J Med
Obesity, sleep apnea, and hypertension
Hypertension
Risk factors for obstructive sleep apnea in adults
JAMA
Excess weight and sleep-disordered breathing
J Appl Physiol
Prospective study of the association between sleep-disordered breathing and hypertension
N Engl J Med
Obstructive sleep apnoea is independently associated with an increased prevalence of metabolic syndrome
Eur Heart J
Sleep-disordered breathing is related to an increased risk for type 2 diabetes in middle-aged men, but not in women - the FIN D2D-survey
Diabetes Obes Metab
Sleep-disordered breathing and self-reported general health status in the Wisconsin Sleep Cohort Study
Sleep
Sleep-disordered breathing and mortality: a prospective cohort study
PLoS Med
Effects of cognitive-behavioural weight loss programme on overweight obstructive sleep apnoea
Sleep Res
The effects of a very low-calorie diet-induced weight loss on the severity of obstructive sleep apnoea and autonomic nervous function in obese patients with obstructive sleep apnoea syndrome
Clin Physiol
Weight loss in mildly to moderately obese patients with obstructive sleep apnea
Ann Intern Med
Polysomnography before and after weight loss in obese patients with severe sleep apnoea
Int J Obes
Persistence of obstructive sleep apnea after surgical weight loss
J Clin Sleep Med
Medical therapy for obstructive sleep apnoea: a review by medical therapy for obstructive sleep apnea task force of the standards of practice committee of the American Academy of Sleep Medicine
Sleep
Lifestyle intervention with weight reduction-first line treatment in mild obstructive sleep apnea
Am J Respir Crit Care Med
A randomized study on the effect of weight loss on obstructive sleep apnea among obese patients with type 2 diabetes: the Sleep AHEAD study
Arch Intern Med
Effect of a very low energy diet on moderate and severe obstructive sleep apnoea in obese men: a randomised controlled trial
BMJ
Longer term effects of very low energy diet on obstructive sleep apnoea in cohort derived from randomised controlled trial: prospective observational follow-up study
BMJ
Sustained improvement in mild obstructive sleep apnea by diet and physical activity based lifestyle intervention- post-interventional follow-up
Am J Clin Nutr
Prevalence of obesity and trends in the distribution of body mass index among US adults, 1999–2010
JAMA
Individual and aggregate years-of-life-lost associated with overweight and obesity
Obesity
The economic burden of obesity worldwide: a systematic review of the direct costs of obesity
Obes Rev
Epidemiology of obstructive sleep apnea: a population health perspective
Am J Respir Crit Care Med
Obstructive sleep apnea patients use more health resources ten years prior to diagnosis
Sleep Res Online
Abdominal fat and sleep apnea: the chicken or the egg?
Diabetes Care
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2023, AppetiteCitation Excerpt :The association between living with OSA and persons with overweight has been previously reported in the literature (e.g., Carneiro-Barrera et al., 2019; Edwards et al., 2019; Leppänen et al., 2019), with 60–90% of adults with OSA being reported as living with overweight (Leppänen et al., 2019). The co-existence of obesity and OSA can greatly increase an individual's risk of developing several comorbid conditions, such as type 2 diabetes, stroke, cognitive impairment, depression, and cardiovascular disease (Al-Qattan et al., 2021; Tuomilehto et al., 2013). While obesity is considered a risk factor for the development of OSA, there is considerable evidence that OSA also impacts upon weight and it is likely, therefore, that this is a bidirectional relationship.
Cognitive Complaints and Comorbidities in Obstructive Sleep Apnea
2022, Sleep Medicine ClinicsCitation Excerpt :There is strong evidence that excess weight (eg, morbid obesity) is one of the strongest predictive factors in OSA47 in both adults as well as children,48 with obese children recently showing a 46% prevalence of OSA compared with 33% of children seen in a general pediatric clinic.49 Indeed, obesity may be one of the most important risk factors to monitor for OSA because the majority of OSA patients (ie, approximately two-thirds) are obese and there is an overrepresentation of OSA in obese patients as well.50 Although the relationship between weight and OSA is still somewhat unclear, specific areas of fat distribution (eg, neck, waist, and abdominal areas with excessive fat tissue) have been specifically related to OSA.46
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The most important references are denoted by an asterisk.