Did you know that...
- Being overweight or obese is a major risk factor for the development of obstructive sleep apnoea.
- Weight loss is an effective means of treating or reducing the severity of sleep apnoea. A 10% weight loss can lead to a 26% reduction in the severity of OSA.
- Lifestyle modification is the cornerstone of weight control, and works best in combination with other therapies tailored to your individual needs.
- Surgery is currently the most effective treatment for severe obesity.
Why obesity is bad for your health and sleep?
Being overweight or obese is an increasingly serious health burden in Australia and worldwide. In the Australian adult population, an estimated 67% of males and 52% of females were classified as overweight or obese in 1999-2000. Excess body weight poses a significant risk of developing chronic illnesses particularly diabetes, high blood pressure, high cholesterol, heart disease and some cancers. As such, those who are overweight or obese may die younger than those of normal body weight.
In a recent update of US data (Framingham study), an average reduction in life expectancy of 5.8 and 7.1 years may be seen in 40 year old non-smoking males and females respectively compared with those of normal body weight of the same age.
Although obstructive sleep apnoea (OSA) may result from a combination of several different causes, obesity remains the dominant risk factor. How then does obesity increase the likelihood of the upper airway collapsing repeatedly during sleep?
- Being overweight or obese changes the nature of the upper airway tissues. Patients with OSA have been shown to have thicker pharyngeal walls, and excess tongue and soft palate tissues. These changes appear to be more pronounced in males compared to females with OSA, and result in a smaller airway due to overcrowding of the airway by these structures.
- Excess body weight reduces lung volume when lying on the back (supine posture). This can result in a decrease in the traction or normal ‘tug’ on the upper airway as the diaphragm and inter-connected structures inside the chest are displaced upward, effectively causing the upper airway to become more floppy.
Thus obesity can result in a more floppy and smaller upper airway. To make matters worse, muscles that work to hold the airway open are also less effective in patients with OSA. The end result is that the upper airway in an obese person tends to collapse more easily in sleep. All these effects can be improved by weight loss.
Will my sleep apnoea improve with weight loss?
There is now very little doubt that losing excess body weight is an effective way of treating or reducing the severity of OSA in most people. In one study, a 10% weight loss predicted a 26% reduction in the severity of OSA. In our experience a loss of weight of this degree may be enough to reduce the need for the use of therapies such as continuous positive airway pressure (CPAP) in some patients.
How is obesity measured?
The most common method of measuring obesity in the clinic is by use of the body mass index (BMI). This is a standardised calculation of your height and weight measured as part of your medical consultation. The BMI is a product of your weight in kilograms divided by your height in metres squared, weight/(height)2. Click here to calculate your BMI.
Weight classification for adults based on BMI (World Health Organisation, 2000)
|Underweight||Less than 18.5|
|Class 1 obesity||30.0-34.9|
|Class 2 obesity||35.0-39.9|
|Class 3 obesity||40 or more|
*BMI ranges may differ for non-caucasian groups
Weight loss management program
There are a range of specialties involved in treating obesity. This will eventually culminate in a multidisciplinary team aimed at providing a holistic weight loss service. Your general practitioner should continue to have a key role in your care.
The fundamental aim of a weight control program involves determining:
- How much weight to lose.
- How to lose weight.
How much weight to lose?
The simplest answer to this question is the more the better, to a normal weight range (see BMI above). Studies have shown that even a modest weight loss of 5–10% of body weight can produce significant health benefits with cardiovascular risk reduction and control of diabetes, not to mention improvements in control of OSA. As such, an initial goal to reduce 10% of body weight over 6 months would be reasonable for most patients. This goal may change over time depending on your progress. A realistic expectation and regular review of progress are key aspects of the treatment process.
How to lose weight?
Lifestyle factors underlie the vast majority of cases of obesity in our society with rarer contribution from genetic and medical causes. Therefore, a successful weight control program needs to focus on lifestyle modification in combination with other interventions tailored to an individual patient’s needs. Current options for weight loss are diet, exercise, medications and surgery.
Diet and exercise
This is usually the starting point in the treatment program. It makes sense that for weight loss to occur, a decrease in caloric consumption would work best when coordinated with an increase in the energy expenditure. A lifestyle modification program needs to be tailored, taking into account the motivational level and specific health problems of each patient. This may involve:
- Expert dietary advice to help restructure your diet.
- An increase in physical activity either by way of incidental activity (daily activities such as walking and climbing stairs), and/or specific exercise program.
- Attending support groups such as Weight Watchers.
Regular reviews are required to ensure that strategies are implemented and that necessary alterations to the plan are accommodated. Our team is also considering instituting psychological intervention for more structured behavioural techniques in selected cases.
Weight loss (bariatric) surgery
There has been considerable interest in this area as surgery is currently the most effective treatment for severe obesity. The surgical techniques usually result in some form of gastric restriction to limit food intake. In motivated and morbidly obese patients, surgical procedures can result in weight loss in the order of 16-43% (varying between 22 and 63 kilograms) over 1 to 2 years. The weight loss needs to be maintained with a closely supervised weight management plan thereafter. Laparoscopic banding (a form of ‘key-hole’ surgery) is now the most commonly used procedure in Australia, although other techniques (such as gastric bypass) are also available.
Who should go for weight loss surgery?
Surgery is currently indicated for those patients with a BMI greater than 40, or with a BMI greater than 35 and serious medical problems including OSA. These patients would usually have been unsuccessful in achieving weight loss by diet and exercise. Should surgery be considered, it is crucial that other health problems such as diabetes, blood pressure, heart disease and OSA are well controlled prior to the procedure to limit complications. There are very few of these surgical procedures being performed in the public health system and access to these operations is improved if you have private health cover.
Prevention is better than cure
The major challenge in weight loss treatment is achieving sustained weight control. It also makes perfect sense to prevent obesity than to treat it. This will require individuals, the community, health care professionals and the government to put in a concerted effort to effect changes in our lifestyle and environment for a healthier living.