Given that obesity is the only major modifiable risk factor for obstructive sleep apnoea, it may seem superfluous to perform a randomised controlled trial of an intervention to reduce weight.1 Indeed, a recent Cochrane review looking at weight loss in this disorder found no relevant randomised controlled trials.2

This has been a major gap in the evidence based treatment of sleep apnoea. In the linked randomised controlled trial (doi:10.1136/bmj.b4609), Johansson and colleagues assess whether weight loss due to a very low energy diet reduces moderate and severe obstructive sleep apnoea in obese men who were all using continuous positive airway pressure.3

Research has emphasised mechanical interventions for obstructive sleep apnoea, such as nasal continuous positive airway pressure or mandibular advancement splints. Mechanical treatments may be efficacious in that they limit the condition when used, but they are less effective over the medium to long term,4 possibly because of difficulties with adherence.5 …