The Swedish study involved 63 obese men with an average weight of 248 pounds. Their average age was 49 years. Sleep apnea was measured using a home sleep test.
All of the men had moderate to severe OSA and were being treated with CPAP therapy. They had an average apnea-hypopnea index of 37 breathing pauses per hour of sleep. An AHI of more than 30 is considered “severe” OSA.
Thirty men were assigned to the treatment group. The other 33 men acted as a control group.
The men in the treatment group were put on the Cambridge Diet for seven weeks. This is a very low-energy, liquid diet. It uses a powder that is mixed with water to replace every meal of the day.
After the seven-week diet normal foods were gradually introduced for two weeks. Treatment also involved group sessions for support and motivation.
Results show that men in the treatment group lost an average of 41 pounds. Twenty-two of the 30 men were no longer obese.
This weight loss produced an improvement in sleep apnea severity. The mean AHI of the treatment group dropped from 37 to 12.
Seventeen percent of the men no longer had sleep apnea. Fifty percent had mild sleep apnea with an AHI of less than 15. Men who initially had severe OSA showed the greatest improvement in AHI.
In a press release the authors noted that a very low-energy diet is not a general solution to weight problems. Typically it is used in the first phase of a long-term treatment program.
They also wrote that the main limitation of the study was its short duration. Weight regain is common after weight loss. Evaluating the long-term effectiveness of weight loss would require at least one year.
The study was funded in part by Cambridge Manufacturing Company Limited, which markets the Cambridge Diet.
The AASM recommends dietary weight loss as one treatment strategy for people who are obese and have sleep apnea. But weight loss should be combined with another treatment such as CPAP or an oral appliance.
In October the Sleep Education Blog reported on another study involving a low-energy diet and OSA. Read more about weight loss and sleep apnea.
Image by Becky Lai