BMI is a misleading proxy for adiposity in longitudinal studies with adolescent males: The Australian LOOK study

Richard D. Telford, Rohan M. Telford, Marijke Welvaert

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Objectives: Despite evidence suggesting caution, employment of body mass index (BMI, kg m−2) as a proxy for percentage of body fat (PFat) in longitudinal studies of children and adolescents remains commonplace. Our objective was to test the validity of change in BMI as a proxy for change in PFat measured by dual-energy X-ray absorptiometry (DXA) during adolescence. Design: Longitudinal study. Methods: Healthy, predominantly Australian youth of mainly Caucasian background (131 females and 115 males) underwent repeated measures at 12.0 (SD 0.3) and 16.0 (SD 0.3) years for height, weight and PFat (DXA). Results: There was no significant difference in the percentage changes in BMI and PFat for the females (β = 2.45, standard error (SE) = 1.39, 95% confidence interval (CI) = [−0.27; 5.17]) with their mean BMI increasing 15% as their mean PFat increased 18%. However, for the males, while their mean BMI also increased 15%, their mean PFat was reduced 25%; this change being highly significant (β = −42.25, SE = 2.23, 95% CI = [−46.22, −38.27]). Conclusions: While change in BMI is likely to be a rough proxy for change in PFat measured by DXA in longitudinal studies of adolescent females, this is not the case for adolescent males, where increased BMI is likely to correspond with decreased PFat. Consequently, inferences from longitudinal studies of adolescents which have assumed that an increase in BMI (or BMI Z-scores or percentiles) represents an increase in adiposity require reconsideration.

LanguageEnglish
Pages307-310
Number of pages4
JournalJournal of Science and Medicine in Sport
Volume22
Issue number3
DOIs
Publication statusPublished - Mar 2019

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Adiposity
Proxy
Longitudinal Studies
Adipose Tissue
Photon Absorptiometry
Confidence Intervals
Body Mass Index
Weights and Measures

Cite this

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title = "BMI is a misleading proxy for adiposity in longitudinal studies with adolescent males: The Australian LOOK study",
abstract = "Objectives: Despite evidence suggesting caution, employment of body mass index (BMI, kg m−2) as a proxy for percentage of body fat (PFat) in longitudinal studies of children and adolescents remains commonplace. Our objective was to test the validity of change in BMI as a proxy for change in PFat measured by dual-energy X-ray absorptiometry (DXA) during adolescence. Design: Longitudinal study. Methods: Healthy, predominantly Australian youth of mainly Caucasian background (131 females and 115 males) underwent repeated measures at 12.0 (SD 0.3) and 16.0 (SD 0.3) years for height, weight and PFat (DXA). Results: There was no significant difference in the percentage changes in BMI and PFat for the females (β = 2.45, standard error (SE) = 1.39, 95{\%} confidence interval (CI) = [−0.27; 5.17]) with their mean BMI increasing 15{\%} as their mean PFat increased 18{\%}. However, for the males, while their mean BMI also increased 15{\%}, their mean PFat was reduced 25{\%}; this change being highly significant (β = −42.25, SE = 2.23, 95{\%} CI = [−46.22, −38.27]). Conclusions: While change in BMI is likely to be a rough proxy for change in PFat measured by DXA in longitudinal studies of adolescent females, this is not the case for adolescent males, where increased BMI is likely to correspond with decreased PFat. Consequently, inferences from longitudinal studies of adolescents which have assumed that an increase in BMI (or BMI Z-scores or percentiles) represents an increase in adiposity require reconsideration.",
keywords = "Adiposity, Adolescents, Body composition, Longitudinal, Weight status",
author = "Telford, {Richard D.} and Telford, {Rohan M.} and Marijke Welvaert",
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doi = "10.1016/j.jsams.2018.08.002",
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BMI is a misleading proxy for adiposity in longitudinal studies with adolescent males : The Australian LOOK study. / Telford, Richard D.; Telford, Rohan M.; Welvaert, Marijke.

In: Journal of Science and Medicine in Sport, Vol. 22, No. 3, 03.2019, p. 307-310.

Research output: Contribution to journalArticle

TY - JOUR

T1 - BMI is a misleading proxy for adiposity in longitudinal studies with adolescent males

T2 - Australian Journal of Science and Medicine in Sport

AU - Telford, Richard D.

AU - Telford, Rohan M.

AU - Welvaert, Marijke

PY - 2019/3

Y1 - 2019/3

N2 - Objectives: Despite evidence suggesting caution, employment of body mass index (BMI, kg m−2) as a proxy for percentage of body fat (PFat) in longitudinal studies of children and adolescents remains commonplace. Our objective was to test the validity of change in BMI as a proxy for change in PFat measured by dual-energy X-ray absorptiometry (DXA) during adolescence. Design: Longitudinal study. Methods: Healthy, predominantly Australian youth of mainly Caucasian background (131 females and 115 males) underwent repeated measures at 12.0 (SD 0.3) and 16.0 (SD 0.3) years for height, weight and PFat (DXA). Results: There was no significant difference in the percentage changes in BMI and PFat for the females (β = 2.45, standard error (SE) = 1.39, 95% confidence interval (CI) = [−0.27; 5.17]) with their mean BMI increasing 15% as their mean PFat increased 18%. However, for the males, while their mean BMI also increased 15%, their mean PFat was reduced 25%; this change being highly significant (β = −42.25, SE = 2.23, 95% CI = [−46.22, −38.27]). Conclusions: While change in BMI is likely to be a rough proxy for change in PFat measured by DXA in longitudinal studies of adolescent females, this is not the case for adolescent males, where increased BMI is likely to correspond with decreased PFat. Consequently, inferences from longitudinal studies of adolescents which have assumed that an increase in BMI (or BMI Z-scores or percentiles) represents an increase in adiposity require reconsideration.

AB - Objectives: Despite evidence suggesting caution, employment of body mass index (BMI, kg m−2) as a proxy for percentage of body fat (PFat) in longitudinal studies of children and adolescents remains commonplace. Our objective was to test the validity of change in BMI as a proxy for change in PFat measured by dual-energy X-ray absorptiometry (DXA) during adolescence. Design: Longitudinal study. Methods: Healthy, predominantly Australian youth of mainly Caucasian background (131 females and 115 males) underwent repeated measures at 12.0 (SD 0.3) and 16.0 (SD 0.3) years for height, weight and PFat (DXA). Results: There was no significant difference in the percentage changes in BMI and PFat for the females (β = 2.45, standard error (SE) = 1.39, 95% confidence interval (CI) = [−0.27; 5.17]) with their mean BMI increasing 15% as their mean PFat increased 18%. However, for the males, while their mean BMI also increased 15%, their mean PFat was reduced 25%; this change being highly significant (β = −42.25, SE = 2.23, 95% CI = [−46.22, −38.27]). Conclusions: While change in BMI is likely to be a rough proxy for change in PFat measured by DXA in longitudinal studies of adolescent females, this is not the case for adolescent males, where increased BMI is likely to correspond with decreased PFat. Consequently, inferences from longitudinal studies of adolescents which have assumed that an increase in BMI (or BMI Z-scores or percentiles) represents an increase in adiposity require reconsideration.

KW - Adiposity

KW - Adolescents

KW - Body composition

KW - Longitudinal

KW - Weight status

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DO - 10.1016/j.jsams.2018.08.002

M3 - Article

VL - 22

SP - 307

EP - 310

JO - Australian Journal of Science and Medicine in Sport

JF - Australian Journal of Science and Medicine in Sport

SN - 1440-2440

IS - 3

ER -