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Abstract Introduction The mechanism of weight gain after continuous positive airway pressure (CPAP) treatment for treating obstructive sleep apnea (OSA) has not been fully elucidated. We hypothesized that CPAP treatment could result in positive energy expenditure through lowering basal metabolic rate (BMR) and increasing nutrition intake which the later associated with delayed bedtime and shorter sleep duration. That led to increase in body weight and fat mass. Methods The consecutive patients with untreated moderate-severe OSA assessed with 7-day Actiwatch, 3-day intake dietary, repeated polysomnography, BMR, body composition, and blood check. Participants were randomized to CPAP or usual care and reassessed 12 weeks later. The primary outcome was resting energy expenditure (REE) and respiratory quotien (RQ) while second outcomes were nutrition intake, eating behavior, and fat/fat free mass. Third outcomes were objectively measured mid-sleep time and sleep hour. The APAP effect was assessed with between-group differences in outcome changes. Results From 66 patients recruited, 26 patients each were randomized to CPAP and usual care, which 21 patients and 24 patients completed the study, respectively. Compared to usual care, CPAP treatment was not associated with changes in REE and RQ, total caloric intake, fat mass, mid-sleep time and sleep hour, while it was associated with increase in body mass index (mean difference 0.6 kg/m2, 95% confidence interval, 0.07 to 1.19), fat free mass, and fat intake, and less Cognitive Restraint eating. Conclusion The short-term CPAP treatment had no effect on energy expenditure and sleep pattern though it increased weight, fat free mass, fat intake, and improve eating behavior. Support (if any) NSTC (111-2314-B-002-293), NTU (107L900502, 108L900502, 109L900502), NTHU (109-42, 111-S0298, 111-X0033); MediaTek Inc. (201802034 RIPD)
Lee et al. (Sat,) studied this question.