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Energy expenditure at rest and during sleep in children with Prader-Willi syndrome is explained by body composition
E A van Mil1, K R Westerterp, W J Gerver
1Departments of Human Biology, Pediatrics, Clinical Genetics, and Methodology and Statistics, Maastricht University, Maastricht, Netherlands. g.vanmil@hb.unimaas.nl
Insights
Young Prader-Willi syndrome (PWS) patients have lower basal metabolic rate (BMR) and sleeping metabolic rate (SMR) due to reduced fat-free mass, not differences in metabolic rate itself.
Area of Science:
- Endocrinology
- Metabolism
- Genetics
Background:
- Obesity in Prader-Willi syndrome (PWS) is linked to a low basal metabolic rate (BMR).
- Abnormal sleep patterns in PWS may also impact sleeping metabolic rate (SMR).
Purpose of the Study:
- To evaluate BMR and SMR, adjusted for fat-free mass, in young PWS patients.
- To compare metabolic rates between PWS patients and matched obese controls.
Main Methods:
- 17 PWS patients and 17 matched obese controls (aged 7.5-19.8 years) participated.
- Body composition was assessed using deuterium dilution.
- BMR and SMR were measured using ventilated-hood and respiratory chamber systems, respectively.
Main Results:
- PWS patients exhibited significantly lower BMR and SMR than controls.
- After adjusting for fat-free mass, no significant differences in BMR or SMR were observed between groups.
- PWS patients had lower absolute and height-adjusted fat-free mass.
Conclusions:
- The lower BMR and SMR in young PWS patients are primarily attributed to their reduced fat-free mass.
- Metabolic rates per unit of fat-free mass do not differ significantly between PWS patients and controls.
Background:
Obesity in Prader-Willi syndrome (PWS) seems to be related to a low basal metabolic rate (BMR). In addition, abnormal sleep patterns reported in PWS might affect sleeping metabolic rate (SMR).
Objective:
Our objective was to assess BMR and SMR adjusted for fat-free mass in young PWS patients.
Design:
Subjects were 17 PWS patients (10 females and 7 males aged 7.5-19.8 y) and 17 obese control subjects matched for sex and bone age. SMR was measured in a respiratory chamber, BMR with a ventilated-hood system, and body composition by deuterium dilution.
Results:
BMR and SMR were significantly lower in the PWS group than in the control group (5.36 +/- 1.18 and 4.62 +/- 1.08 MJ/d compared with 6.38 +/- 1.55 and 5.60 +/- 1.52 MJ/d, respectively; P < 0.05). When fat-free mass was included in the analysis, multiple regression showed no differences in BMR and SMR between groups. When weight was included in the analysis instead of fat-free mass, SMR was lower in the PWS group. Fat-free mass was lower in the PWS group both as an absolute value and when adjusted for height.
Conclusion:
BMR and SMR are low in young patients with PWS because of a low fat-free mass.