Research: Effect of a very low energy diet on moderate and severe obstructive sleep apnoea in obese men: A randomized controlled trial
Weight loss reduces obstructive sleep apnoea in obese men, with the greatest effect seen in patients with severe disease, according to new research published on bmj.com today.
Obstructive sleep apnoea is a common sleep disorder characterised by pauses in breathing during sleep. Each episode (apnoea) lasts for at least 10 seconds and is caused by the collapse of the upper airways during sleep.
Moderate and severe obstructive sleep apnoea (defined as 15 or more apnoeas per hour) carries an excess risk of motor vehicle crashes, heart disease and death. Yet only one study has examined the effects of weight loss on obstructive sleep apnoea.
So researchers at the Karolinska Institute in Sweden set out to evaluate whether treatment with a low energy diet reduces moderate and severe obstructive sleep apnoea in obese men.
The study involved 63 obese men (BMI 30-40) aged 30-65 years with moderate to severe obstructive sleep apnoea who were being treated with continuous positive airway pressure (a mask designed to help breathing during sleep).
Thirty men received a liquid very low energy diet for seven weeks to promote weight loss, followed by two weeks of gradual introduction of normal food. The remaining men acted as a control group by adhering to their usual diet over the nine weeks.
Both groups attended regular clinical examinations throughout the study to measure weight, waist circumference, and body fat, and to test dietary compliance. For the diet group, each visit also included a one hour group session to build group support and provide motivation.
At the start of the study, both groups had a mean apnoea hypopnoea index (AHI) of 37 apnoeas per hour. At week nine, the diet group had a mean AHI of 12 events per hour compared with 35 events per hour in the control group.