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Effect of a very low energy diet on moderate and severe obstructive sleep apnoea in obese men: a randomised controlled trial

BMJ 2009; 339 doi: (Published 04 December 2009) Cite this as: BMJ 2009;339:b4609
  1. Kari Johansson, PhD student1,
  2. Martin Neovius, postdoctoral research fellow12,
  3. Ylva Trolle Lagerros, physician12,
  4. Richard Harlid, physician3,
  5. Stephan Rössner, professor1,
  6. Fredrik Granath, statistican2,
  7. Erik Hemmingsson, postdoctoral research fellow1
  1. 1Obesity Unit, Department of Medicine, Karolinska Institutet, Stockholm, Sweden
  2. 2Clinical Epidemiology Unit, Department of Medicine, Karolinska Institutet
  3. 3Aleris Fysiologlab, Stockholm
  1. Correspondence to: K Johansson, Obesity Unit, M73, Karolinska Institutet, Department of Medicine, SE-141 86 Stockholm, Sweden kari.johansson{at}
  • Accepted 13 September 2009


Objective To assess the effect of weight loss induced by a very low energy diet on moderate and severe obstructive sleep apnoea in obese men.

Design Single centre, two arm, parallel, randomised, controlled, open label trial. Blocked randomisation procedure used for treatment allocation.

Setting Outpatient obesity clinic in a university hospital in Stockholm, Sweden.

Participants 63 obese men (body mass index 30-40, age 30-65 years) with moderate to severe obstructive sleep apnoea (apnoea-hypopnoea index (AHI) ≥15), treated with continuous positive airway pressure.

Interventions The intervention group received a liquid very low energy diet (2.3 MJ/day) for seven weeks to promote weight loss, followed by two weeks of gradual introduction of normal food, reaching 6.3 MJ/day at week 9. The control group adhered to their usual diet during the nine weeks of follow-up.

Main outcome measure AHI, the major disease severity index for obstructive sleep apnoea. Data from all randomised patients were included in an intention to treat analysis (baseline carried forward for missing data).

Results Of the 63 eligible patients, 30 were randomised to intervention and 33 to control. Two patients in the control group were dissatisfied with allocation and immediately discontinued. All other patients completed the trial. Both groups had a mean AHI of 37 events/h (SD 15) at baseline. At week 9, the intervention group’s mean body weight was 20 kg (95% confidence interval 18 to 21) lower than that of the control group, while its mean AHI was 23 events/h (15 to 30) lower. In the intervention group, five of 30 (17%) were disease free after the energy restricted diet (AHI <5), with 15 of 30 (50%) having mild disease (AHI 5-14.9), whereas the AHI of all patients in the control group except one remained at 15 or higher. In a subgroup analysis of the intervention group, baseline AHI significantly modified the effectiveness of treatment, with a greater improvement in AHI in patients with severe obstructive sleep apnoea (AHI >30) at baseline compared with those with moderate (AHI 15-30) sleep apnoea (AHI −38 v −12, P<0.001), despite similar weight loss (−19.2 v −18.2 kg, P=0.55).

Conclusion Treatment with a low energy diet improved obstructive sleep apnoea in obese men, with the greatest effect in patients with severe disease. Long term treatment studies are needed to validate weight loss as a primary treatment strategy for obstructive sleep apnoea.

Trial registration Current Controlled Trials ISRCTN70090382.


  • We thank the staff at the Obesity Unit, the staff at Aleris Fysiologlab for assistance with the sleep studies, and the participating patients.

  • Contributors: KJ, MN, SR and EH conceived the study hypothesis. YLT and SR met all the patients. RH performed the sleep studies. KJ, MN, and FG did the statistical analyses. KJ and EH wrote the first draft of the manuscript. MN, SR, YLT, and RH provided critical input at all stages and critically reviewed and contributed to the final draft. All authors are guarantors.

  • Funding: This study was partly supported by a grant from Cambridge Manufacturing Company Limited and Novo Nordisk Scandinavia AB. The funders played no part in the analysis or write up of this paper.

  • Competing interests: None declared.

  • Ethical approval: The regional ethics committee in Stockholm, Sweden, approved the study.

  • Data sharing: No additional data available.

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