CPAP effect on energy balance, chronotype, hormone, and body composition: a randomized controlled trial

<bold>Background:</bold> Continuous positive airway pressure (CPAP) therapy for treating obstructive sleep apnea (OSA) has been associated with weight gain. We hypothesized CPAP therapy could reduce energy expenditure, promote intake and result in change in body composition, which was associated with alteration of sleep/wake behavior and hormone. This randomized controlled trial (RCT) aimed to exam the CPAP effect on energy expenditure at rest and on-exertion, objectively measured intake, physical activity (PA) and chronotype, hormone, and body composition. <bold>Method:</bold> Consecutive patients of untreated moderate-severe OSA were enrolled from two centers and randomized to 12-week CPAP or inactive control. The primary outcome was basal metabolic rate (BMR); second outcomes were photographed intake, eating behavior, body composition; third outcomes were PA and chronotype measured by Actiwatch, and hormone. The CPAP effect was assessed with between-group differences in outcome changes. <bold>Result:</bold> 52 participants with median 45.9 years and body mass index (BMI) 28.1 kg/m2 were randomized to CPAP and control which 21 in CPAP and 24 in control completed the trial. CPAP therapy (median usage 5.9 hour/day) was not associated with changes in BMR, caloric intake, fat mass, PA, chronotype, adiponectin, and leptin while it was associated with increase in BMI, fat free mass, fat intake, and Ghrelin; and decrease in Restrain Eating and cortisol. <bold>Conclusion:</bold> Though high-compliance CPAP therapy had no effect on exergy expenditure, caloric intake, and chronotype, it could promote fat intake, hunger hormone, and lower Restrain Eating and stress hormone, which may attribute to increase in BMI and fat free mass.