DAILY ENERGY-EXPENDITURE IN FREE-LIVING CONDITIONS IN OBESE AND NONOBESE CHILDREN - COMPARISON OF DOUBLY LABELED WATER ((H2O)-H-2-O-18) METHOD AND HEART-RATE MONITORING

OBJECTIVE: To compare the heart-rate monitoring with the doubly labell ed water ((H2O)-H-2-O-18) method to estimate total daily energy expend iture in obese and non-obese children. DESIGN: Cross sectional study o f obese and normal weight children. SUBJECTS: 13 prepubertal children: six obese (4M, 2F, 9.1 +/- 1.5 years, 47.3 +/- 9.7 kg) and seven non- obese (3M, 4F, 9.3 +/- 0.6 years, 31.8 +/- 3.2 kg). MEASUREMENTS: Tota l daily energy expenditure was assessed by means of the doubly labelle d water method (TEE(DLW)) and of heart-rate monitoring (TEE(HR)). RESU LTS: TEE(HR) was significantly (P < 0.05) higher than TEE(DLW) in obes e children (9.47 +/- 0.84 MJ/d vs 8.99 +/- 0.63 MJ/d) whereas it was n ot different in non-obese children (8.43 +/- 2.02 MJ/d vs 8.42 +/- 2.3 0 MJ/d, P = NS). The difference of TEE assessed by HR monitoring in th e obese group averaged 6.2 +/- 4.7%. At the individual level, the degr ee of agreement (difference between TEE(HR) and TEE(DLW) +/- 2s.d.) wa s low both in obese (-0.36, 1.32 MJ/d) and in nonobese children (-1.30 , 1.34 MJ/d). At the group level, the agreement between the two method s was good in non-obese children (95% c.i. for the bias:-0.59, 0.63 MJ /d) but not in obese children (0.04, 0.92 MJ/d). Duration of sleep and energy expenditure during resting and physical activity were not sign ificantly different in the two groups. Patterns of heart-rate (or deri ved energy expenditure) during the day-time were similar in obese and non-obese children. CONCLUSION: The HR monitoring technique provides a n estimation of TEE close to that assessed by the DLW method in nan-ob ese prepubertal children. In comparison with DLW, the HR monitoring me thod yields a greater TEE value in obese children.