Wright, C. M. , Cole, T. J., Fewtrell, M., Williams, J. E., Eaton, S. and Wells, J. C. (2022) Body composition data show that high body mass index centiles over-diagnose obesity in children under 6 years. American Journal of Clinical Nutrition, 116(1), pp. 122-131. (doi: 10.1093/ajcn/nqab421) (PMID:34967839) (PMCID:PMC9257461)
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Abstract
Background: Most authorities define childhood overweight / obesity as body mass index (BMI) exceeding the same high centile cut-off throughout childhood, but it seems unlikely that true obesity prevalence (excess body fat) is constant though childhood. Objective: We investigated how fat mass and lean mass, adjusted for height, relate to BMI and each other across childhood, using a uniquely large database of body composition measures, estimated using gold standard methods. Design: Cross-sectional and cohort data were collated from representative samples of healthy children aged 6 weeks to 20 years and children attending obesity clinics aged 7-16 years. Body composition was measured by deuterium dilution up to age 4 years, and by either deuterium or the criterion 4-component model from 4-20 years. Fat and lean mass were expressed as fat mass index (FMI; fat mass/height2) and lean mass index (LMI; lean mass/height2). Results: There were 2367 measurements of weight, height, and body composition from 1953 individuals. Before age 6 years, the variability in FMI, LMI and BMI was much less than after, FMI was low (mainly <8 kg/m2) and FMI and LMI were weakly negatively correlated. From mid-childhood, upper limits for both BMI and FMI rose, but FMI in children with BMI < 91st centile still rarely exceeded 8 kg/m2. With increasing age, the correlation of FMI with LMI rose to 0.5-0.7, driven mainly by children with a high FMI also having a high LMI. Conclusions: Raised fat levels are much less common at young compared to older ages, and young children with a high BMI centile have lower FMI than older children with the same BMI centile. Current BMI centile cut-offs thus over-diagnose obesity in younger groups. More stringent cut-offs are required for children under 6 years, matching the World Health Organization recommendation for 0-5 years.
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Wright, Professor Charlotte |
Authors: | Wright, C. M., Cole, T. J., Fewtrell, M., Williams, J. E., Eaton, S., and Wells, J. C. |
College/School: | College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing |
Journal Name: | American Journal of Clinical Nutrition |
Publisher: | Oxford University Press |
ISSN: | 0002-9165 |
ISSN (Online): | 1938-3207 |
Published Online: | 30 December 2021 |
Copyright Holders: | Copyright © 2021 The Authors |
First Published: | First published in American Journal of Clinical Nutrition 116(1): 122-131 |
Publisher Policy: | Reproduced under a Creative Commons License |
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