Researchers at the Karolinska Institutet, a Swedish university that is among the leading medical universities in Europe, recently reported the results of their study on weight loss as a treatment for sleep apnea. The findings, published in the December 2009 issue of British Medical Journal, indicate that weight loss may indeed be a cure for sleep apnea. According to researcher Kari Johansson, “Our findings suggest that weight loss may be an effective treatment strategy for sleep apnea in obese men.”
What Is Sleep Apnea?
Sleep apnea – characterized by the repeated but temporary cessation of breathing during sleep – is a relatively common disorder, particularly among men and people who are overweight or obese. Five or more interruptions in breathing per hour during sleep is considered a disease, and it can have serious consequences. Moderate and severe sleep apnea increase the risk of premature death, and untreated sleep apnea is associated with increased health problems like stroke and heart disease, as well as incidents like traffic accidents. Unfortunately, as sleep apnea is an under-diagnosed disease, many suffers do go untreated.
The Study
The study took place at an outpatient obesity clinic in a university hospital in Stockholm, Sweden. The participants were 63 obese men (Body Mass Index between 30 and 40) who were between 30 and 65 years of age. All participants were diagnosed as having moderate to severe obstructive sleep apnea as measured by the apnea-hypopnea index (AHI), the standard index of severity for the disease. The participants were all receiving treatment for sleep apnea in the form of continuous positive airway pressure (CPAP), which alleviates symptoms of sleep apnea by producing more normal breathing patterns during sleep.
The study was randomized, in this case meaning that participants were randomly assigned to one of two groups. The control group continued their typical diet throughout the nine-week study, while those assigned to the intervention group were placed on a very low calorie diet (VLCD). For the first seven weeks, participants in the control group received a liquid diet of 554 kcal per day; normal food was gradually introduced during the final two weeks of the study, building up to 1,500 kcal per day.
The Results
Participants in the intervention group lost an average of 19 pounds during the nine week study, and the number of apnea events they experienced was cut by more than half. At the end of the study, one in six participants in the intervention group was cured of sleep apnea, half had only mild sleep apnea, and none of the patients were suffering from severe sleep apnea. The participants who began the study with severe sleep apnea showed the greatest benefit from the weight loss program.
Sleep Apnea And Very Low Calorie Diet (VLCD)
In order to achieve such significant weight loss, the intervention group was put on an extremely restrictive liquid diet. As Kari Johansson explains, “We often use VLCD in the form of a low calorie powder as part of the treatment of obese patients with a serious comorbidity, such as sleep apnea. The powder is mixed with water and replaces every meal of the day, which gives a rapid loss of weight. It’s also a good way of boosting the patients’ motivation.” The VLCD used in the study was Cambridge diet, a low-calorie powder marketed by Cambridge Manufacturing Company Limited, which funded a portion of the study (the company did not influence the study or its results). Other VLCD products include Nutrilett, Naturdiet and Allevo.
The VLCD was a success, but the researchers make a point to note that the VLCD is just the first phase of a long-term weight management program. In order to keep the weight off, patients will need to make changes in their diet and exercise habits. To help participants in the study maintain their weight loss, the researchers invited them to take part in a year-long behavioral change program.
Few treatment options are currently available for obstructive sleep apnea, with the most common treatment being the use of CPAP during sleep. Although weight loss is often advocated as a treatment method, until now little high quality scientific evidence was available to support this treatment strategy. This randomized study, looking at patients with moderate and severe forms of sleep apnea, provides important evidence that weight loss may indeed be a promising treatment strategy for moderate to severe sleep apnea.
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