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General obesity or abdominal obesity - what should we be focussing
upon in children? Dr. David McCarthy RNutr
Institute for Health Research & Policy
London Metropolitan University
13th February 2008Oxford Obesity Seminars
What is the time bomb?
• Type 2 diabetes• Hypertension• Metabolic Syndrome• CVD• Stroke
Diagnostic Criteria for Metabolic Syndrome in Children
• 3 or more of the following:
– BMI >98th centile– TG>95th centile– HDL <5th centile– SBP +/- DBP>95th centile– Impaired GTT
National Child Measurement Programme• One element of the Government’s work programme
on childhood obesity
• Inform local planning and delivery of services for children; gather population-level surveillance data to allow analysis of trends in growth patterns and obesity.
• http://www.dh.gov.uk/en/Policyandguidance/Healthandsocialcaretopics/Healthyliving/DH_073787
UK 1990 BMI References
Cole et al. Arch Dis Child (1995) 73: 25-29
Some drawbacks of BMI in children
• Age-dependent• Correlates with both
fat mass and fat-free mass
• Low sensitivity• no indication of
body fat distribution
• ‘Although body mass index is simple to measure and has been a valuable tool in monitoring trends in obesity, it also has numerous disadvantages. Principally it does not distinguish between increased mass in the form of fat, lean tissue or bone, and hence can lead to significant misclassification.’McCarthy et al. 2006
• ‘The fact that body mass index represents only a crude proxy for body fat and may produce a significant level of misclassification is universally accepted but widely ignored. This is because, in the absence of alternative measures, the advantages of body mass index have outweighed its disadvantages.’McCarthy et al. 2006
Correlation of BMI with Fat Mass (kg)
r2 = 0.763, P<0.0001
16-18 year olds
Correlation of BMI with Fat Free Mass (kg)
r2 = 0.514, P<0.0001
16-18 year olds
Misclassification by BMI
• Overweight/obese children can be classified as normal
• At least 6.5% overfat/obese children misclassified by BMI*
• *McCarthy et al. unpublished observations
Abdominal fat in adults
• Visceral fat, intra-abdominal fat
• Strongly linked to morbidity
• insulin resistance and hyperinsulinaemia
• Waist circumference – a measure of abdominal, intra-abdominal and visceral fat
Waist Measurement
• Now a common measure in adults
• Risk for diabetes, hypertension and CVD
• Cut-offs identified• Where do you take the
waist measurement?
Central body fat accumulation in children
• Intra-abdominal adipose tissue
• Subcutaneous abdominal adipose tissue
• assessed by girth and skinfold measurements
Intra-abdominal fat and morbidity in children
• Brambilla et al. 1994
• Caprio et al. 1995, 1996
• Owens et al. 1998
• Adverse changes in blood lipids, insulin and blood pressure
Is waist circumference in children linked to risk?
Adverse lipoprotein profile in 12-14 year olds (Flodmark et al. 1994)
Adverse insulin levels in 5-17 year olds Freedman et al. 1999)
Raised systolic blood pressure in 4-5 year olds (Jarrett, McCarthy et al, 2002, unpublished)
WC percentile charts for children
• Cuban (Martinez et al. 1994)
• Italian (Zannolli & Morgese 1996)
• Spanish (Moreno et al. 1999)
• UK (McCarthy et al. 2001)
• Canadian (Katzmarzyk et al. 2004)
• US (Fernandez et al. 2004)
• Australian (Eisenmann et al. 2005)
4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
Age (years)
40
50
60
70
80
Wai
st c
ircu
mfe
ren
ce (
cm)
Boys
Girls
Waist in children
n, 8355McCarthy et al. 2001
Development of WC centile charts for the UK children
Child Growth Foundation
BMI-WC relationship
Subject Age BMI WC BMI %ile WC %ile (y) (cm)
A 7.7 15.2 48 ~50th <9th
B 7.5 15.3 65 ~50th >98th
C 7.1 19.1 53 >91st ~50th
D 7.1 20.0 67 >98th >99.6th
Has upper body fatness increased in British children?
Comparison of data collected 10 and 20 years apart
BSI and NDN surveys
McCarthy et al. 2003. BMJ 326: 624
NDNS boys
NDNS girls BSI boys
BSI girls
McCarthy et al. 2003. BMJ 326: 624
NDNS girls
NDNS boys
BSI girlsBSI boys
Changes over 10-20 years in mean BMI and waist circumference in British children aged 11-16 years.
Mean SD Score (SD) Mean increaseover time (SE)
BSI 1977/87 NDNS 1997Male Female Male Female Male Female
BMI -0.05 -0.15 0.42 0.38 0.47 0.53(1.02) (0.99) (1.13) (1.09) (0.06) (0.06)
WC 0.00 0.00 0.84 1.02 0.84 1.02(0.99) (1.00) (1.02) (1.33) (0.06) (0.06)
McCarthy et al. 2003. BMJ 326: 624
Changes over 10-20 years in overweight and obesity based on BMI and waist circumference in British children aged 11-16 years. Values are % exceeding 91st centile (98th centile)
% prevalence of overweight % change (obesity) over time
BSI 1977/87 NDNS 1997Male Female Male Female Male Female
BMI 7.7 5.9 20.6 17.3 12.9 11.4(3.3) (1.6) (10.0) (8.3) (6.8) (6.6)
WC 8.7 8.8 28.5 38.1 19.8 29.3(3.3) (3.1) (13.8) (17.1) (10.7) (14.5)
McCarthy et al. 2003. BMJ 326: 624
Are these changes in WC also seen in younger children?
The ALSPAC Study
Avon Longitudinal Study of Parents And Children
• ALSPAC comprises 14,000 children born in the Avon region during 1991 and 1992 (Golding et al. 2001).
• Children in Focus (CIF) is a subset of this cohort (approx. 1000 children)
• For this study, BMI and WC from the CIF cohort were compared with equivalent BSI data between 2.5 and 5 years
BSI BMI CIF BMI
n Age(y)
Mean (SD)(kgm2)
Median(kgm2)
n Age(y)
Mean (SD)(kgm2)
Median(kgm2)
D(kgm2)
% D
Boys
182 2.5 16.4 (1.3) 16.3 528 2.5 16.7* (1.3) 16.6 0.29 1.8
205 3.5 16.3 (1.4) 16.1 580 3.5 16.5* (1.2) 16.4 0.22 1.4
195 4.5 16.0 (1.3) 15.8 563 4 16.2* (1.3) 16.1 0.26 1.6
251 5.5 15.9 (1.2) 15.7 534 5 16.0 (1.4) 15.9 0.09 0.6
Girls
186 2.5 16.3 (1.3) 16.1 429 2.5 16.5* (1.3) 16.4 0.27 1.7
185 3.5 16.0 (1.4) 15.9 467 3.5 16.5* (1.5) 16.3 0.42 2.6
210 4.5 16.0 (1.4) 15.9 454 4 16.2* (1.5) 16.1 0.26 1.6
406 5.5 15.5 (1.6) 15.2 445 5 16.1* (1.6) 15.9 0.63 4.1
McCarthy HD et al. (2005). Increasing waist circumferences in young British children - a comparative study. Int J Obesity 29: 157-162.
Results - BMI
BSI waist circumference CIF waist circumference
n Age (y)
Mean (SD) (cm)
Median (cm)
n Age (y)
Mean (SD) (cm)
Median (cm)
D (cm)
%D
Boys
182 2.5 48.4 (3.0) 48.3 536 2.5 50.4* (3.0) 50.3 1.99 4.1
206 3.5 50.9+ (3.1) 50.4 575 3.5 51.7* (3.0) 51.7 0.76 1.5
195 4.5 51.9+ (3.1) 51.6 559 4.0 52.5* (3.2) 52.4 0.60 1.2
251 5.5 52.3+ (3.2) 52.5 531 5.0 53.1* (3.5) 52.8 0.86 1.6
Girls
186 2.5 47.8 (2.8) 47.6 433 2.5 50.2* (3.1) 50.2 2.50 5.2
185 3.5 49.8 (3.1) 49.7 467 3.5 51.7* (3.6) 51.6 1.88 3.8
210 4.5 51.0 (3.6) 50.6 454 4 52.3* (3.6) 52.0 1.34 2.6
406 5.5 51.3 (3.7) 51.2 444 5 52.9* (4.2) 52.3 1.53 2.9
McCarthy HD et al. (2005). Increasing waist circumferences in young British children - a comparative study. Int J Obesity 29: 157-162.
Results – Waist Circumference
Increase in central fatness in British youths and pre-
school children
Hackney
Hackney Demography• Relatively young
population• 50% from black and
minority ethnic groups• High rates of social
and economic deprivation
• CVD death rate twice national average
• High prevalence of type 2 diabetes
Hackney Children's Obesity Survey
Ethnicity-related variation in upper body fatness in East London schoolchildren. By DIMPLE SAMANI1, LIZ PROSSER2, COLIN ALSTON2, and H. DAVID McCARTHY1, 1Institute for Health Research & Policy, London Metropolitan University, Holloway Rd, London N7 8DB, 2The Learning Trust, 1 Reading Lane, London, E8 1GQ.
Proceedings of the Nutrition Society (2007, in press)
Caucasian Mixed S. Asian Caribbean African Other
M F M F M F M F M F M F
n 437 394 125 113 224 215 199 176 286 291 102 105
Ht SDS
0.12 0.26 -0.05 0.50 0.50 0.12
WC
SDS
0.68 0.81 0.51 0.32 0.02 0.12 0.57 0.81 0.65 0.98 0.58 0.52
WHtR 0.45 0.45 0.45 0.44 0.44 0.44 0.44 0.45 0.45 0.45 0.45 0.45
Hackney Children’s Obesity Survey Measures of central fatness across ethnic groups
Caucasian
Mixed S. Asian Caribbean
African Other
M F M F M F M F M F M F
Overwt %
WC
27.2 25.8 24.0 20.4 17.9 19.5 23.6 33.0 29.7 38.6 28.4 28.6
Obese %
WC
14.4 13.5 9.6 8.8 8.5 8.4 12.1 18.8 12.9 21.6 11.8 9.5
Overwt %
BMI
21.7 19.5 17.6 18.7 14.1 15.7 23.0 27.0 27.0 28.0 11.5 15.9
Obese %
BMI
10.4 9.9 5.6 6.9 5.8 6.0 13.5 16.5 13.3 17.8 6.8 6.5
%>
WHtR
0.50
17.6 17.0 12.7 8.7 10.0 11.2 12.1 16.5 11.5 17.9 13.7 15.2
Prevalence of obesity across ethnic groups using different assessment criteria
Key Findings• Within a socially homogenous group of
children, variation in upper body fatness is evident
• Ethnic variation was striking• Prevalence of upper body obesity based solely
upon WC in South Asian was not as great as in other ethnic groups
• When height is accounted for, ethnicity-related variation is less obvious
• Caution should be exercised when interpreting WC measures between children from different ethnic groups
Problems with waist measurement
• No universally agreed definition of measurement site
• Measure over skin or clothing?
• Difficulty with very obese subjects
• Sensitivity issues
Waist circumference measurement
Midway between the 10th riband the iliac crest
WHO standard method
Used by :
McCarthy et al. 2001Freedman et al. 1999Moreno et al. 1999
Waist circumference measurementcontinued.
At the level of the umbilicus
Used for the waist circumference percentiles in Italian children, Zanolli & Morgese. 1996
Dimple Samani-Radia
Conclusions• BMI can fail to identify all
children at risk of obesity-related morbidity
• Abdominal fatness strongly linked to morbidity
• Waist girth measurement is a useful adjunct to BMI
• Upper body fatness has increased in young children and in youths
• Greater attention should be paid to central obesity in children
Acknowledgements
• Dimple Samani
• Karen Jarrett
• ALSPAC team
• Tanita UK
• NoCLoR
• The Learning Trust
• IHRP
• Tim Cole
Thank you
New children's body fat charts
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