General obesity or abdominal obesity - what should we be focussing upon in children?

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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 2008
• Oxford Obesity Seminars

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What is the time bomb?

• Type 2 diabetes
• Hypertension
• Metabolic Syndrome
• CVD
• Stroke

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Diagnostic Criteria for Metabolic Syndrome in
Children

• 3 or more of the following
• BMI gt98th centile
• TGgt95th centile
• HDL lt5th centile
• SBP /- DBPgt95th centile
• Impaired GTT

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National Child Measurement Programme

• One element of the Governments 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/Healthan
  dsocialcaretopics/Healthyliving/DH_073787

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UK 1990 BMI References
Cole et al. Arch Dis Child (1995) 73 25-29
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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

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• 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
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• 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
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Correlation of BMI with Fat Mass (kg)
16-18 year olds
r2 0.763, Plt0.0001
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Correlation of BMI with Fat Free Mass (kg)
16-18 year olds
r2 0.514, Plt0.0001
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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

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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

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Waist Measurement

• Now a common measure in adults
• Risk for diabetes, hypertension and CVD
• Cut-offs identified
• Where do you take the waist measurement?

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Central body fat accumulation in children

• Intra-abdominal adipose tissue
• Subcutaneous abdominal adipose tissue
• assessed by girth and skinfold measurements

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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

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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)

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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)

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Development of WC centile charts for the UK
children
n, 8355
McCarthy et al. 2001
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Child Growth Foundation
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BMI-WC relationship

• Subject Age BMI WC BMI ile WC ile
  (y) (cm)
• A 7.7 15.2 48 50th lt9th
• B 7.5 15.3 65 50th gt98th
• C 7.1 19.1 53 gt91st 50th
• D 7.1 20.0 67 gt98th gt99.6th

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Has upper body fatness increased in British
children?

• Comparison of data collected 10 and 20 years
  apart
• BSI and NDN surveys

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NDNS boys
NDNS girls
BSI boys
BSI girls
McCarthy et al. 2003. BMJ 326 624
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NDNS girls
NDNS boys
BSI girls BSI boys
McCarthy et al. 2003. BMJ 326 624
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Changes over 10-20 years in mean BMI and waist
circumference in British children aged 11-16
years. Mean SD Score (SD) Mean
increase over time (SE) BSI 1977/87 NDNS
1997 Male 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) (1.3
3) (0.06) (0.06) McCarthy et al. 2003. BMJ
326 624
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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
1997 Male 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
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Are these changes in WC also seen in younger
children?

• The ALSPAC Study

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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

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Results - BMI
BSI BMI BSI BMI BSI BMI BSI BMI CIF BMI CIF BMI CIF BMI CIF BMI
n Age (y) Mean (SD) (kgm2) Median (kgm2) n Age (y) Mean (SD) (kgm2) Median (kgm2) D (kgm2) D
Boys Boys Boys Boys Boys Boys Boys Boys Boys 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 Girls Girls Girls Girls Girls Girls Girls Girls 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.
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Results Waist Circumference
BSI waist circumference BSI waist circumference BSI waist circumference BSI waist circumference BSI waist circumference CIF waist circumference CIF waist circumference CIF waist circumference CIF waist circumference
n Age (y) Mean (SD) (cm) Median (cm) Median (cm) n Age (y) Mean (SD) (cm) Median (cm) D (cm) D
Boys Boys Boys Boys Boys Boys Boys Boys Boys Boys Boys
182 2.5 48.4 (3.0) 48.3 536 536 2.5 50.4 (3.0) 50.3 1.99 4.1
206 3.5 50.9 (3.1) 50.4 575 575 3.5 51.7 (3.0) 51.7 0.76 1.5
195 4.5 51.9 (3.1) 51.6 559 559 4.0 52.5 (3.2) 52.4 0.60 1.2
251 5.5 52.3 (3.2) 52.5 531 531 5.0 53.1 (3.5) 52.8 0.86 1.6
Girls Girls Girls Girls Girls Girls Girls Girls Girls Girls Girls
186 2.5 47.8 (2.8) 47.6 433 433 2.5 50.2 (3.1) 50.2 2.50 5.2
185 3.5 49.8 (3.1) 49.7 467 467 3.5 51.7 (3.6) 51.6 1.88 3.8
210 4.5 51.0 (3.6) 50.6 454 454 4 52.3 (3.6) 52.0 1.34 2.6
406 5.5 51.3 (3.7) 51.2 444 444 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.
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Increase in central fatness in British youths and
pre-school children
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Hackney
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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

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Hackney Children's Obesity Survey
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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)

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Hackney Childrens Obesity Survey Measures of
central fatness across ethnic groups
Caucasian Caucasian Mixed Mixed S. Asian S. Asian Caribbean Caribbean African African African Other Other
M F M F M F M F M M F M F
n 437 394 125 113 224 215 199 176 286 286 291 102 105
Ht SDS 0.12 0.12 0.26 0.26 -0.05 -0.05 0.50 0.50 0.50 0.50 0.50 0.12 0.12
WC SDS 0.68 0.81 0.51 0.32 0.02 0.12 0.57 0.81 0.65 0.98 0.98 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 0.45
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Prevalence of obesity across ethnic groups using
different assessment criteria
Caucasian Caucasian Mixed Mixed S. Asian S. Asian Caribbean Caribbean African African Other 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
gt 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
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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

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Problems with waist measurement

• No universally agreed definition of
  measurement site
• Measure over skin or clothing?
• Difficulty with very obese subjects
• Sensitivity issues

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Waist circumference measurement
Midway between the 10th rib and the iliac crest
WHO standard method
Used by McCarthy et al. 2001 Freedman et al.
1999 Moreno et al. 1999
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Waist circumference measurement continued.
At the level of the umbilicus
Used for the waist circumference percentiles
in Italian children, Zanolli Morgese. 1996
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Dimple Samani-Radia
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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

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Acknowledgements

• Dimple Samani
• Karen Jarrett
• ALSPAC team
• Tanita UK
• NoCLoR
• The Learning Trust
• IHRP
• Tim Cole

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Thank you
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New children's body fat charts