How well do waist circumference and body mass index reflect body composition in pre-pubertal children?
OBJECTIVE
To investigate the quantitative relationship between waist circumference (WC) and height (Ht), and subsequently the association between waist circumference index (WCI), body mass index (BMI) and body composition in pre-pubertal children.


METHODS
Cross-sectional sample (n=227; boys=127) of pre-pubertal black children (age range 8.8-11.0 years) from the Bone Health sub-study of the Bt20 birth cohort study set in Soweto-Johannesburg, South Africa. Measures of height, weight and WC by anthropometry, total and truncal fat and lean mass by dual-energy X-ray absorptiometry were used in the analysis. Pearson's correlation coefficients were used to examine the associations between BMI, WC and body composition outcomes.


RESULTS
WC was independent of height when height was raised to a power of approximately 0.8. BMI and WCI (WC/Ht) were significantly associated with total and truncal fat and lean mass in both sexes (all P<0.001). BMI showed consistently and significantly higher correlations with body composition than WCI and this association was significantly greater for fat mass than lean mass.


CONCLUSIONS
BMI, rather than WCI, would be a better screening tool for total and truncal fat mass in both sexes before puberty.
Cameron
N
N
Department of Human Sciences, Centre for Human Development and Ageing, Loughborough University, Loughborough, UK. N.Cameron@lboro.ac.uk
Jones
L L
LL
Griffiths
P L
PL
Norris
S A
SA
Pettifor
J M
JM
D015502:Absorptiometry, Photon; D000273:Adipose Tissue; D050154:Adiposity; D044383:Black People; D001823:Body Composition; D001827:Body Height; D015992:Body Mass Index; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D050177:Overweight / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000208:ethnology; D013019:South Africa; D055105:Waist Circumference