Weight loss induced by a very low energy liquid diet reduces moderate and severe obstructive sleep apnea (OSA) in obese men, according to a Swedish research team.

By the end of their study, the apnea-hypopnea index (AHI) was reduced by 67% in the calorie-restricted group but not at all in the control group, note Kari Johansson at Karolinska Institutet in Stockholm and colleagues in the British Medical Journal, published online on December 4.

Their randomized trial involved 63 men, ages 30-65, with BMI between 30 and 40. At baseline, the AHI averaged 37 events/hour in both groups. The active intervention involved a 2.3 megajoules (MJ) (about 550 calories) per day liquid diet for 7 weeks, followed by 2 weeks of a gradual return to normal food, scheduled to reach 6.3 MJ/d (about 1,500 calories) by week 9.

At week 9, men in the intervention group had lost a mean of 18.7 kg, while the control group had a mean gain of 1.1 kg. Twenty-two of 30 intervention patients were no longer obese.

Also, the authors report, the mean AHI had declined to 12 events/hour in the intervention group, compared with 35 events/hour in the control group.

The authors saw a dose-response relationship between weight loss and change in AHI. However, those with severe OSA benefited most from the intervention.

Similar findings were reported in the Archives of Internal Medicine this past September 28 (see Reuters Health report, September 30, 2009). In that trial, 264 patients with diabetes with a mean BMI of 36.7 and a mean AHI of 23 events/hour were randomized to either a behavioral weight loss program tailored to obese diabetics or to a diabetes support program.

One year later, weight loss in the tailored program was significantly greater, mean AHI was lower, and 14% of patients had complete remission of their OSA.

BMJ 2009.