The relationship between skinfold thickness and body mass index in North European Caucasian and East Asian women with anorexia nervosa: Implications for diagnosis and management

RESEARCH ARTICLE

The Relationship Between Skinfold Thickness and BodyMass Index in North European Caucasian and East AsianWomen With Anorexia Nervosa: Implications ForDiagnosis and Managementy

Nerissa L. Soh1*, Stephen Touyz2,3z, Timothy A. Dobbins4, Simon Clarke5,6, Michael R. Kohn5,6,Ee Lian Lee7, Vincent Leow8x, Ken EK Ung9 & Garry Walter1,10z

1
Child and Adolescent Mental Health Services, Northern Sydney Central Coast Area Health Service, New South Wales, Australia
2School of Psychology, University of Sydney, New South Wales, Australia

3Peter Beumont Centre for Eating Disorders, New South Wales, Australia

4School of Public Health, University of Sydney, New South Wales, Australia

5Department of Adolescent Medicine and Centre for Research Into Adolescent’S Health (CRASH), Westmead Hospital, Westmead, New

South Wales, Australia

6Faculty of Medicine, University of Sydney, New South Wales, Australia

7Department of Behavioural Medicine, Singapore General Hospital, Singapore

8Private Practice, Grosvenor Street, Bondi Junction, New South Wales, Australia

9Adam Road Hospital, Singapore

10Department of Psychological Medicine, University of Sydney, New South Wales, Australia

Abstract

Objective: To investigate the relationship between skinfold thickness and body mass index (BMI) in North European

Caucasian and East Asian young women with and without anorexia nervosa (AN) in two countries.

Method: Height, weight and skinfold thicknesses were assessed in 137 young women with and without AN, in

Australia and Singapore. The relationship between BMI and the sum of triceps, biceps, subscapular and iliac crest

skinfolds was analysed with clinical status, ethnicity, age and country of residence as covariates.

Results: For the same BMI, women with AN had significantly smaller sums of skinfolds than women without AN.

East Asian women both with and without AN had significantly greater skinfold sums than their North European

Caucasian counterparts after adjusting for BMI.

Conclusion: Lower BMI goals may be appropriate whenmanaging AN patients of East Asian ancestry and the weight

for height diagnostic criterion should be reconsidered for this group. Copyright# 2008 JohnWiley & Sons, Ltd and

Eating Disorders Association.

Keywords

skinfolds; body mass index; anorexia nervosa; diagnostic criteria; ethnicity

*Correspondence

Nerissa L. Soh, Coral Tree Family Service, P.O. Box 142, North Ryde, NSW 1670, Australia. Tel: þ61 2 8877 5371. Fax: þ61 2 9887 2941.

Email: [email protected]

Published online 7 August 2008 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/erv.893

yPart of this manuscript was presented at the Dietitians Association of Australia’s 24th Annual Conference in May 2006 and submitted as part

of a doctoral thesis to The University of Sydney.

zProfessor.

xConsultant Psychiatrist.

Eur. Eat. Disorders Rev. 17 (2009) 31–39 � 2008 John Wiley & Sons, Ltd. and Eating Disorders Association. 31

Ethnic Body Composition Differences in AN N. L. Soh et al.

Introduction national Classification of Diseases (ICD-10) (World

Body mass index (BMI) is used as an indicator of

appropriate weight for height for optimum health and

appears to be a respectable indicator of excess fat in

North European Caucasian men and women in Europe

and North America. However, it is unlikely to be as

suitable in other populations (World Health Organiz-

ation, 1995) as the World Health Organization (WHO)

has noted a lack of evidence to support different

populations with the same BMI distribution having

similar profiles of morbidity and mortality, on the basis

of overweight and obesity (de Onis & Habicht, 1996).

There are ethnic differences in the relationship

between level of body fat and BMI (WHO, 2000) and

body composition differences have been observed by

numerous authors (Rush et al., 2004; Sampei, Novo,

Juliano, Colugnati, & Sigulem, 2003). Studies have

demonstrated that most non-North European groups

have greater levels of body fat for the same BMI when

compared to North European Caucasians and new BMI

cut-off values have been proposed to denote overweight

and obesity in Asians (Goh, Tain, Tong, Mok, &Wong,

2004; Misra, 2003; Regional Office for the Eastern

Pacific of the World Health Organization: The

International Association for the Study of Obesity

and the International Obesity Task Force, 2000) and

other ethnic groups (Mirmiran, Esmaillzadeh, & Azizi,

2004; Rush et al., 2004). However, populations of Asian

ancestry are not ethnically homogenous and there are

differences in body composition between Asian groups

(Deurenberg-Yap, Schmidt, van Staveren, & Deuren-

berg, 2000; Shiwaku et al., 2005), albeit with a common

theme of lower average BMI and greater tendency

towards abdominal obesity when compared to non-

Asians (WHO Expert Consultation, 2004).

Although much emphasis has been placed on the

adverse effects of high BMI and excess body fat on

health (WHO, 2000), it should be emphasised that the

‘U-shaped’ relationship between BMI and morbidity or

mortality (Deurenberg & Yap, 1999) also delineates the

increased risk of clinical problems associated with being

underweight (WHO, 2000). Anorexia nervosa (AN) is

characterised by extreme emaciation and the high

mortality rate associated with it is of great concern as it

usually develops in adolescence (Beumont & Touyz,

2003). For a diagnosis of AN, both the Diagnostic and

Statistical Manual of Mental Disorders (DSM-IV)

(American Psychiatric Association, 1994) and Inter-

32 Eur. Eat. Disorders Rev. 17 (200

Health Organization, 1992) include criteria that body

weight be maintained at or below 85% of normal weight

for height and in addition, the ICD-10 provides an

alternative criterion, that BMI be 17.5 or lower. As

patients presenting for AN treatment are becoming

ethnically diverse, it has been suggested that lower BMI

cut-offs should be applied in Asian patients (Lee, 2001;

Ung, 2003).

Ung (2003) reported that the BMI of Asians is on

average lower than that of Caucasians, justifying the use

of a lower BMI. Lee (2001) also commented on the

lower BMI of Chinese women, recommending a BMI of

less than 16 to clinically diagnose AN in Chinese

groups. The relationship between body fatness and BMI

is of interest as the majority of patients with AN are

female and adipose tissue is believed to directly

influence fertility (Frisch, 1990). To date, studies in

body composition and AN have not taken ethnicity into

account (Kerruish et al., 2002; Scalfi et al., 2002). The

present study aims to investigate the relationship

between skinfold thickness—which is closely associated

with total body density and fat (Westrate & Deuren-

berg, 1989)—and BMI in North European Caucasian

and East Asian young women with and without AN in

two countries. We hypothesise that women of East

Asian ancestry will have greater skinfold thicknesses for

the same BMI when compared to North European

Caucasian women and that this relationship will hold in

the presence of AN.

Methods

Participants

This study’s data form a subset from a larger cross-

cultural study into eating disorders. Participants were

137 women aged 14–35 of North European Caucasian

or East Asian ethnicity who were undergoing treatment

for AN (n¼ 38) as diagnosed by a psychiatrist and

classified by DSM-IV criteria (American Psychiatric

Association, 1994), and healthy control women who

had never been diagnosed with an eating disorder

(n¼ 99). Participants in Australia were either born in

Australia or migrated to Australia by the age of 12.

Ethnicity was self-identified and the description ‘East

Asian’ ethnicity includes participants who identified as

having Chinese, Vietnamese or Korean ancestry.

9) 31–39 � 2008 John Wiley & Sons, Ltd. and Eating Disorders Association.

N. L. Soh et al. Ethnic Body Composition Differences in AN

Participants with AN were recruited from four

teaching hospitals in Sydney and two teaching hospitals

in Singapore. Control participants were recruited from

a number of sites: North European and East Asian

Australians through The University of Sydney; East

Asian Singaporeans from the nursing staff of one of the

hospitals in Singapore and North European expatriates

from staff and students of an international school in

Singapore. Exclusion criteria were non-fluency in

spoken or written English, the participant being

pregnant or lactating or the participant having in situ

silicone implants. The study was approved by the

relevant ethics committees in Sydney and Singapore.

Written informed consent was obtained from all

participants. Where participants were deemed minors,

consent was obtained from the participants’ parents.

Measurements

Height, weight and skinfold thicknesses were assessed

with the participant lightly clad using the International

Society for the Advancements of Kinanthropometry

technique (ISAK, 2001) by the first author who has

Level 1 Technician (restricted profile) certification from

ISAK. Stretched height was recorded using a graph

paper wall chart and headboard to the nearest

millimetre and weight was recorded using digital scales

(Tanita 1618) to the nearest 200 g. Skinfold thicknesses

were taken from the right side of the body with

Harpenden callipers at the triceps, subscapular, biceps

and iliac crest (suprailiac) sites (Norton & Olds, 1996)

to the nearest 0.1mm. Measurements were recorded in

duplicate and a third measurement was taken where

height and weight duplicates were more than 2% apart

and where skinfold duplicates were more than 10%

apart. Median heights and weights were used to

calculate the BMI. The sum of four skinfolds was

calculated frommedian triceps, subscapular, biceps and

iliac crest skinfolds. This sum was used as an index of

body fatness as it is implemented in the widely used

Durnin and Womersley equations for estimating body

density (Durnin & Womersley, 1974).

Statistical analyses

Statistical analyses were performed with SPSS version

11.5.0 software. Intra-rater relative technical errors of

measurement (%TEM) were calculated for height,

weight and individual skinfolds, with lower values

Eur. Eat. Disorders Rev. 17 (2009) 31–39 � 2008 John Wiley & Sons, Ltd. and Ea

indicating greater precision (Norton & Olds, 1996).

Intraclass correlation coefficients (ICC) were calculated

as a measure of reliability, with high reliability indicated

by ICC values close to 1 (Norton & Olds, 1996). One-

way analyses of variance with post hoc Scheffe tests were

conducted across the cultural and diagnostic groups for

age, height, weight and the individual skinfolds.

To assess the impact of ethnicity, country of

residence and clinical (AN/control) status on BMI,

multiple linear regression of BMI was undertaken on to

ethnicity, country of residence, clinical status and age.

The interactions between ethnicity and clinical status

and ethnicity and country of residence were tested using

the backwards elimination process. To assess the impact

of ethnicity, country of residence and clinical status on

the association between BMI and body fatness, multiple

linear regression of the sum of four skinfolds was

conducted against BMI, ethnicity, age, country of

residence and clinical status. For this second model, the

interactions between ethnicity and BMI, ethnicity and

clinical status, BMI and age, ethnicity and country of

residence and BMI and country of residence were

tested, also using backwards elimination. Age was

included throughout for face validity. Categorical

variables were coded using dummy variables to

facilitate multiple linear regression analyses.

Results

Table 1 shows mean age, height, weight, skinfold

thicknesses, BMI and sum of four skinfolds. For

skinfold measurements, %TEM values were 3.4–5.7%,

and those for height and weight were 0.2% and 0.07%,

respectively, meeting proposed post-profiling targets

for Level 1 anthropometrist accreditation (Norton &

Olds, 1996). ICC values ranged from 0.98 to 1 for all

measurements. The duration of illness for 29 of the

participants with AN was known, the mean being 3.79

years (SD 2.96).

Descriptive statistics

There were significant differences in age (F6,130¼ 3.54,

p¼ 0.003), height (F6,130¼ 11.93, p< 0.001), weight

(F6,130¼ 13.36, p< 0.001), triceps (F6,130¼ 19.39,

p< 0.001), biceps (F6,130¼ 10.65, p< 0.001), subscap-

ular (F6,130¼ 16.04), p< 0.001) and iliac crest skinfolds

(F6,130¼ 17.23, p< 0.001) across the groups. Detailed

results from post hoc tests are presented below.

ting Disorders Association. 33

Table

1Pa

rtic

ipan

ts’

mea

nag

e,hei

ght,

wei

ght,

body

mas

sin

dex

and

skin

fold

thic

knes

ses

(95%

confiden

cein

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als)

Contr

ol

NEA

�A

Ny

NEA

Contr

ol

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AN

EAAx

Contr

ol

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expat

riat

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Contr

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EAS�

AN

EAS

Tota

l

n32

27

22

212

33

9137

Age

(yea

r)21.5

(20.4

,22.5

)20.7

(19.2

,22.3

)

21.3

(19.8

,22.9

)

16.0

017.3

(13.5

,21.2

)

22.2

(21.1

,23.3

)

20.8

(18.3

,23.4

)

21.0

0

(20.4

,21.6

)

Hei

ght

(cm

)168.0

3

(165.9

1,

170.1

5)

164.9

2

(163.1

5,

166.6

9)

160.9

0

(158.8

1,

162.9

9)

158.3

2166.5

3

(163.2

8,

169.7

8)

159.2

3

(157.5

6,

160.9

0)

158.5

3

(154.4

8,

162.5

8)

163.2

6

(162.2

1,

164.3

0)

Wei

ght

(kg)

60.4

3

(57.6

9,

63.1

7)

45.6

3

(42.7

0,

48.5

7)

57.2

7

(53.2

7,

61.2

8)

36.5

057.1

5

(51.8

8,

62.4

2)

57.4

1

(52.7

9,

62.0

2)

37.4

9

(33.2

1,

41.7

7)

54.1

3

(52.1

7,

56.1

0)

BM

I(k

g/m

2)

21.4

1

(20.5

1,

22.3

1)

16.7

3

(15.8

0,

17.6

6)

22.0

9

(20.7

1,

23.4

6)

14.5

820.6

1

(18.8

3,

22.3

8)

22.5

8

(20.9

6,

24.2

0)

14.9

7

(13.0

6,

16.8

9)

20.2

9

(19.5

9,

20.9

8)

Tric

eps

skin

fold

(mm

)

18.2

3

(16.4

3,

20.0

2)

7.6

1

(5.9

2,

9.3

0)

17.7

2

(15.6

5,

19.7

8)

5.9

016.3

0

(13.3

6,

19.2

4)

18.1

1

(15.9

6,

20.2

5)

7.7

(3.9

4,

11.4

9)

14.9

8

(13.8

3,

16.1

3)

Bic

eps

skin

fold

(mm

)

7.6

6

(6.4

2,

8.9

1)

3.4

6

(2.7

7,

4.1

4)

8.7

6

(7.4

4,

10.0

8)

2.8

07.4

1

(5.2

3,

9.6

0)

8.8

7

(7.3

3,

10.4

1)

3.5

3

(2.3

2,

4.7

3)

6.9

4

(6.2

8,

7.5

9)

Subsc

apula

rsk

info

ld

(mm

)

12.8

4

(11.1

0,

14.5

9)

5.9

9

(5.1

5,

6.8

4)

17.8

5

(14.6

6,

21.0

3)

4.4

210.1

3

(7.4

5,

12.8

2)

18.6

6

(15.5

0,

21.8

2)

6.6

9

(4.4

1,

8.9

7)

12.9

3

(11.6

2,

14.2

5)

Iliac

cres

tsk

info

ld

(mm

)

18.8

0

(15.9

8,

21.6

1)

6.1

7

(4.9

3,

7.4

1)

21.6

1

(18.1

9,

25.0

4)

3.5

516.9

9

(11.6

1,

22.3

7)

17.4

3

(14.9

3,

19.9

4)

6.3

1

(3.1

5,

9.4

7)

15.2

3

(13.7

4,

16.7

3)

Sum

of

four

skin

fold

s

(mm

)

57.5

3

(50.7

0,

64.3

6)

23.2

3

(19.1

8,

27.2

8)

65.9

3

(57.2

6,

74.6

1)

16.6

850.8

4

(38.8

6,

62.8

1)

63.0

7

(54.2

9,

71.8

5)

24.2

4

(14.0

0,

34.4

8)

50.0

9

(45.8

0,

54.3

7)

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34 Eur. Eat. Disorders Rev. 17 (2009) 31–39 � 2008 John Wiley & Sons, Ltd. and Eating Disorders Association
.

Table

2M

ultip

lelin

ear

regre

ssio

nm

odel

sfo

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mas

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and

sum

of

skin

fold

s

Model

Pred

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31

p

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7,

0.1

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(contr

ol¼

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rent)

�4.4

5�

6.0

5,�

2.8

6�

5.5

1<

0.0

01

Ethnic

ity

(Nort

hEu

ropea

nC

auca

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¼re

fere

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1.2

4�

0.1

4,

2.6

21.7

70.0

8

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3

Sum

of

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sBM

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14.2

5,

5.3

617.2

2<

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0<

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Ethnic

ity

(Nort

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6.0

41.8

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�3.1

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7.3

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0.9

9�

1.5

10.1


Age, height and weight

Control East Asian Singaporeans were older than

control expatriates (p¼ 0.02) but there were no other

differences in age (p> 0.07). Control North European

Australians were significantly taller than control East

Asian Australians (p¼ 0.001), control East Asian

Singaporeans (p< 0.001) and AN East Asian Singapor-

eans (p¼ 0.001). Control East Asian Singaporeans were

also shorter than both AN North European Australians

(p¼ 0.007) and control expatriates (p¼ 0.008) while

control expatriates were marginally taller than AN East

Asian Singaporeans (p¼ 0.053). With regard to weight,

control North European Australians were significantly

heavier than AN North European Australians and East

Asian Singaporeans (p< 0.001). Control East Asian

Australians were also heavier than both AN North

European Australians (p¼ 0.007) and East Asian

Singaporeans (p< 0.001), while control East Asian

Singaporeans were heavier than AN North European

Australians (p¼ 0.001) and East Asian Singaporeans

(p< 0.001). Control expatriates were heavier than AN

East Asian Singaporeans (p¼ 0.002) but only margin-

ally heavier than ED North European Australians

(p¼ 0.058). There were no other differences in height

(p> 0.1) or weight (p> 0.06).

Skinfolds

AN North European Australians had significantly

thinner triceps skinfolds than all four control groups

(p� 0.001). AN East Asian Singaporeans also had

thinner triceps skinfolds than control expatriates

(p¼ 0.03) and the other three control groups

(p� 0.001). For the biceps site, AN North European

Australians had thinner skinfolds than control North

European Australians, East Asian Australians and East

Asian Singaporeans (p� 0.001). AN East Asian

Singaporeans had thinner biceps skinfolds than control

East Asian Australians (p¼ 0.02) and East Asian

Singaporeans (p¼ 0.006). For the subscapular skinfold,

AN North European Australians had thinner skinfolds

than both control East Asian Australians and East Asian

Singaporeans (p< 0.001), as well as compared to

control North European Australians (p¼ 0.007). AN

East Asian Singaporeans had thinner subscapular

skinfolds than control East Asian Australians

(p¼ 0.002) and East Asian Singaporeans (p< 0.001).

Among the controls themselves, expatriates had thinner

subscapular skinfolds than East Asian Singaporeans



(p¼ 0.01) and marginally thinner skinfolds than East

Asian Australians (p¼ 0.056), while North European

Australians had thinner subscapular skinfolds than East

Asian Singaporeans (p¼ 0.02). At the iliac crest, AN

North European Australians had thinner skinfolds than

all control groups: North European Australians, East

Asian Australians, East Asian Singaporeans (p< 0.001)

and expatriates (p¼ 0.003). AN East Asian Singapor-

eans also had significantly thinner iliac skinfolds than

control East Asian Singaporeans (p¼ 0.006), both

control North European and East Asian Australians

(p� 0.001), and marginally thinner skinfolds than

expatriates (p¼ 0.052). Among East Asian Australians,

controls had thicker iliac skinfolds than women with

AN (p¼ 0.048). There were no other differences in

skinfold thickness across the groups at the triceps

(p> 0.08), biceps (p> 0.06), subscapular (p> 0.1) or

iliac crest sites (p> 0.1).

The multiple linear regression models for BMI and

sum of skinfolds are presented in turn below. Table 2

shows the partial regression coefficients and their 95%

confidence intervals, test statistics and significance in

the final models. As each participant was coded for

cultural group and for clinical status as two separate

variables, it was decided to retain the AN East Asian

Australian group although there were only two

participants, as they were categorised both as AN

(n¼ 38) and East Asian (n¼ 66).

Body mass index

Of the interactions tested, only the interaction

between clinical status and ethnicity was significant

in the final model (t131¼�2.25, p¼ 0.03). AN

status was significantly associated with lower BMI in

both North European Caucasians (t131¼�5.51,

p< 0.001) and East Asians (t131¼ 6.97, p< 0.001)

after adjusting for age and country of residence, but

there was no difference by ethnicity within the AN

(t131¼�1.45, p¼ 0.2) or control samples (t131¼ 1.77,

p¼ 0.08). Age and country of residence were not

significant.

Sum of four skinfolds against BMI

None of the interactions tested were significant. Higher

BMI, East Asian ethnicity and younger age were each

significantly associated with greater sums of skinfolds


while AN status was associated with lower sums.

Country of residence was not significant.

Discussion

The significantly lower sum of skinfolds in women with

AN compared to controls, in both ethnic groups even

after adjusting for BMI, suggests women with AN have

lower proportions of body fat compared to fat free

mass. This concurs with observations by other authors:

In the starvation that accompanies AN, both lean and

fat mass decrease, with fat mass being preferentially

depleted (Iketani, Kiriike, Nagata, & Yamagami, 1999;

Polito, Cuzzolaro, Raguzzini, Censi, & Ferro-Luzzi,

1998; Scalfi et al., 1997). However, for the same BMI,

women of East Asian ethnicity had significantly greater

sums of skinfolds than women of North European

Caucasian ethnicity, concurring with our hypotheses,

even though East Asian women did not differ from their

North European Caucasian counterparts in BMI after

adjusting for clinical status and age. This is supported

by other studies in East Asians (e.g. Lanham, Stead,

Tsang, & Davies, 2001; Li, Zhang, Yang, Okada, Iwata,

& Harada, 2005; Sampei et al., 2003). The multiple

linear regression model for BMI indicates that in both

North European Caucasians and East Asians, women

with AN have significantly lower BMI values than

controls. However, the mean magnitude of difference

was greater in East Asians (at 7.5 kg/m2) compared to in

North European Caucasians (4.5 kg/m2). As there was

no ethnic difference in control women’s BMI after

adjusting for age and country of residence, the findings

in women with AN suggest the East Asian women with

AN in our study were more emaciated when they were

assessed. Also, skinfold thickness may not correlate with

the total level of body fat during periods of refeeding or

early weight restoration in patients with AN (Rock &

Curran-Celentano, 1994) and the participants in the

present study were at various stages of their treatment.

Thus, a larger study sample and of patients who have

been weight stable for a reasonable duration may be

more informative.

Body composition differences may not be entirely

genetic—that is, not solely attributable to ethnicity—

and environmental factors such as diet, acculturation

and physical activity also influence body composition

(He et al., 2003). The present study did not assess

physical activity levels, but overexercising is common in

AN patients and exerts a nitrogen-sparing effect



(Beumont, Russell, & Touyz, 1993), which may

contribute to the proportionally greater lean body

mass inferred by our findings. Country of residence, a

crude proxy for diet and physical activity in the present

study, was not a significant predictor of BMI, nor was it

significant in the relationship between BMI and the sum

of skinfold thicknesses, suggesting that the differences

observed between ethnic groups were genetic rather

than environmental in nature.

The multiple linear regression model for the sum of

skinfolds indicates that at a BMI of 17.5, North

European Caucasian women in Australia would have

the same sum of skinfolds as East Asian Australian

women with a BMI of 16.2 and East Asian Singaporean

women with a BMI of 16.9. The two values calculated

for East Asian women are not significantly different and

are comparable to Lee’s (2001) proposed BMI cut-off of

16 to clinically diagnose AN in Chinese groups.

Although a number of ethnic-specific reference growth

curves have been produced (e.g. Al-Isa & Thalib, 2006;

Kim, Huang, Woon, Kim, Jo, & Jo, 2005; Leung, Cole,

Tse, & Lau, 1998), previous empirical studies have not

investigated ethnic differences in the relationship

between BMI and body fat levels in underweight

populations and thus have not proposed modifications

to BMI cut-offs to define underweight in specific ethnic

groups. Currently, theWHO still recommends a BMI of

less than 18.5 to classify underweight in Asians (WHO

Expert Consultation, 2004) and while a range of

reference values for percentage body fat have been

published (e.g. Boileau, Lohman, & Slaughter, 1985;

Deurenberg, Yap, & van Staveren, 1998; Lohman,

1995), there is presently no consensus. It would be

premature to derive specific BMI cut-off points to

define underweight in East Asian women from the

present study in view of the relatively small sample size

involved.

In the present study, the sum of skinfolds was not

converted to body density and percentage of body fat,

owing to concerns about the validity of the relevant

regression equations in disease states and in different

ethnic groups (Orphanidou, McCargar, Birmingham,

& Belzberg, 1997). It was also unclear in the present

study whether puberty had been delayed in any of the

participants with AN. However, while the observed

ethnic differences in height were expected (Sampei

et al., 2003), there was no difference in height between

women with and without AN within the one ethnic

group, suggesting that the women with AN in our study


sample were not stunted. The stage of maturity, which

influences body composition, was also not assessed. The

relationship between skinfolds and body density is age-

dependent (Slaughter et al., 1984) and age was

significant and controlled for in the relationship

between BMI and sum of skinfolds. Despite concerns

regarding the use of BMI in adolescents, we found no

difference in BMI by age. Further, removing partici-

pants who were under 18 years old made minimal

differences to the regression models; thus it was decided

to retain the younger participants.

Adipose tissue is believed to directly influence

fertility (Frisch, 1990): It is involved in the metabolism

of sex steroid hormones and the production of

numerous other hormones and cytokines (Fruhbeck,

Gomez-Ambrosi, Muruzabal, & Burrell, 2001). Ame-

norrhoea forms part of the diagnostic criteria for AN

(American Psychiatric Association, 1994; WHO, 1992)

and although its usefulness as a diagnostic criterion has

been questioned (Cachelin &Maher, 1998), its presence

is still of physiological and medical concern (Swenne,

2004). Inadequate levels of body fat contributes to low

oestrogen levels (Støving, Hangaard, & Hagen, 2001)

and ethnic differences in body composition may

therefore influence the BMI required to restore

endocrine normalcy. We were unable to assess the

association between menstrual health and skinfold

thickness in the present study as 18% of our study

sample reported using hormonal contraceptives and in

North European Australians, the proportion was 41%

in controls and 30% in those with AN. It is, however,

worth noting that body fat levels alone do not

determine menstrual health and the impact of

psychological stress on menstrual function has been

highlighted (Swenne, 2004).

Overall, the present study suggests ethnicity should

be taken into account when managing AN patients,

with potentially lower BMI targets required in the

management of AN patients of East Asian ethnicity

compared to North European Caucasian patients. But

before reference values for underweight in East Asians

can be drawn, future empirical studies should be

conducted to assess a greater number of skinfold sites

and implement more direct methods of assessing body

composition. Other factors which affect body compo-

sition, such as physical activity levels, purging

behaviour, stage of refeeding or weight restoration,

and maturity levels, should be taken into account and

the assessment of a larger sample of East Asian women,



and in particular East Asian women with AN, is

recommended. The assessment of patients with AN

who have been weight stable for a reasonable duration is

also advised.

Acknowledgements

We thank the hospital and school staff and all of the

participants. The late Pierre Beumont, Professor of

Psychological Medicine at The University of Sydney,

was an active contributor to this study prior to his

untimely death in October 2003. This study was partly

supported by the Edith Mary Rose Travelling Scholar-

ship and the Faculty of Medicine Postgraduate Scholar-

ship, The University of Sydney.

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The relationship between skinfold thickness and body mass index in North European Caucasian and East Asian women with anorexia nervosa: Implications for diagnosis and management