Body shape in American and British adults: Between-country and inter-ethnic comparisons

Abstract

Recent studies indicate differences between British and American white adults, and between income and ethnic groups within the United States, in the population distribution of lifestyle diseases. Differential prevalence of obesity has been suggested as a contributing factor; however, the conventional approach to categorizing obesity, body mass index, is confounded by ethnic variability in physique.
To compare indices of shape between white British and American adults, and between white, African and Hispanic American adults.
Analysis of two large National Sizing Surveys, using identical study design and three-dimensional (3D) body-scanning instrumentation, on adults aged 17+ years from the UK (3907M and 4710F white), and from the USA (1744M and 3329F white, 709M and 1106F African and 639M and 839F Hispanic).
Weight, height, body circumferences.
In the United States, socio-economic status was associated with increasing height and decreasing waist girth in white and Hispanic, but not African Americans. Compared to white British, white Americans had larger weight and girths, especially waist girth in men. Relative to white Americans, African Americans had smaller relative waist girth, but larger thigh girth, whereas Hispanic Americans had larger relative waist girth.
Body shape of white American adults differs from that of their UK counterparts. Within Americans, ethnic differences in body shape closely track reported differences in prevalence of the metabolic syndrome, implicating variability in central abdominal fat as a key contributing factor. 3D photonic scanning offers a novel approach for categorizing risk of the metabolic syndrome and monitoring treatment success.

Full text

ORIGINAL ARTICLE
Body shape in American and British adults:
between-country and inter-ethnic comparisons
JCK Wells
1
, TJ Cole
2
, D Bruner
3
and P Treleaven
4
1
Childhood Nutrition Research Centre, Institute of Child Health, London, UK;
2
Centre for Paediatric Epidemiology &
Biostatistics, Institute of Child Health, London, UK;
3
[TC]
2
, 211 Gregson Dr, Cary, NC, USA and
4
Department of Computer
Science, University College London, New Engineering Building, Malet Place, London, UK
Background: Recent studies indicate differences between British and American white adults, and between income and ethnic
groups within the United States, in the population distribution of lifestyle diseases. Differential prevalence of obesity has been
suggested as a contributing factor; however, the conventional approach to categorizing obesity, body mass index, is
confounded by ethnic variability in physique.
Objective: To compare indices of shape between white British and American adults, and between white, African and Hispanic
American adults.
Design: Analysis of two large National Sizing Surveys, using identical study design and three-dimensional (3D) body-scanning
instrumentation, on adults aged 17 þ years from the UK (3907M and 4710F white), and from the USA (1744M and 3329F
white, 709M and 1106F African and 639M and 839F Hispanic).
Outcome measures: Weight, height, body circumferences.
Results: In the United States, socio-economic status was associated with increasing height and decreasing waist girth in white
and Hispanic, but not African Americans. Compared to white British, white Americans had larger weight and girths, especially
waist girth in men. Relative to white Americans, African Americans had smaller relative waist girth, but larger thigh girth,
whereas Hispanic Americans had larger relative waist girth.
Conclusions: Body shape of white American adults differs from that of their UK counterparts. Within Americans, ethnic
differences in body shape closely track reported differences in prevalence of the metabolic syndrome, implicating variability in
central abdominal fat as a key contributing factor. 3D photonic scanning offers a novel approach for categorizing risk of the
metabolic syndrome and monitoring treatment success.
International Journal of Obesity (2008) 32, 152–159; doi:10.1038/sj.ijo.0803685; published online 31 July 2007
Keywords: ethnicity; body mass index; waist circumference; 3D photonic scanning; body shape
Introduction
White middle-aged Americans have been found to suffer
from greater rates of diabetes, hypertension, heart disease,
stroke and cancer than their UK counterparts.
1
This finding
was supported by similar differences in underlying physio-
logical markers of risk.
1
Within each country, the risk of
disease was strongly inversely associated with socio-economic
status (SES). The between-country difference was greatest in
low SES groups but was evident at all levels of SES. Some risk
factors (for example, smoking) were similarly distributed
between the two populations, whereas others differed
systematically. Americans have substantially higher rates of
obesity categorized by body mass index (BMI), and the
between-population difference in obesity prevalence was
greatest in those of low-income status.
1
Obesity is a
well-established risk factor for the metabolic syndrome,
2,3
cancer
4
and poor lung function.
5
The prevalence of obesity
in the US rose from 15 to 31% between 1980 and 2003,
whereas in the UK it increased from 7 to 23%.
6
Within the United States, additional studies have high-
lighted differences between the three main ethnic groups
(white, African American and Hispanic) in morbidity and
mortality. African Americans have a lower prevalence of the
metabolic syndrome than the other groups,
6
but higher rates
of cardiovascular mortality.
7,8
In contrast, Hispanics have a
higher prevalence of the metabolic syndrome, especially in
women,
6
but lower rates of cardiovascular mortality.
8,9
Physiological studies indicate that the same level of BMI
confers different metabolic risks in the three groups,
10,11
Received 21 February 2007; revised 2 June 2007; accepted 4 June 2007;
published online 31 July 2007
Correspondence: Dr JCK Wells, Childhood Nutrition Research Centre, Institute
of Child Health, 30 Guilford Street, London WC1N 1EH, UK.
E-mail: J.Wells@ich.ucl.ac.uk
International Journal of Obesity (2008) 32, 152–159
&
2008 Nature Publishing Group All rights reserved 0307-0565/08
$
30.00
www.nature.com/ijo

hence it is unclear about the extent to which obesity
categorized in this way can explain ethnic disparities in
health, as opposed to other factors such as SES.
12
Recognition of the limitations of BMI as an obesity index
has led to proposals for ethnic-specific cutoffs,
13
and
incorporation of data on waist girth, again with ethnic-
specific cutoffs.
14
BMI provides a simple estimate of relative
weight, whereas the health impact of obesity is disproportio-
nately because of central abdominal fat. While visceral fat is
strongly associated with markers of disease risk,
15
reflected
by the strong association between risk of mortality and
waist–hip ratio within narrow BMI bands,
16
thigh girth
appears protective.
17–19
Epidemiological studies are therefore
increasingly focusing on body shape as a more sensitive
marker of disease risk.
Conventionally, body shape is categorized on a simple
basis, such as waist girth, or the waist–hip ratio. Such
measurements are simple to make, but may be considered
invasive due to the need for the measurer to touch the body.
3D photonic scanning has recently emerged as a more
sophisticated approach for the measurement of human body
shape.
20,21
Whole-body scans of surface topography can be
captured in a few seconds using a customized photo booth,
after which software automatically extracts digital informa-
tion on a variety of parameters of body shape. During 2001–
2003, two large sizing surveys were conducted in the United
States and United Kingdom. Using identical protocols, these
surveys allow comparison of body shape between and within
populations. Here, we describe (a) differences between
British and American white adults, and (b) differences
between ethnic groups within Americans, taking into
account variability in education and income status.
Methods
The two National Sizing Surveys, SizeUK and SizeUSA, were
conducted using identical instrumentation, study design
and recruitment strategy. Data were collected in the United
Kingdom during 2001–2002, in eight cities (Birmingham,
Cardiff, Edinburgh, Leeds, London, Manchester, Notting-
ham, Southampton). Data were collected in the United States
during 2002–2003, in 12 cities (Cary, NC; Columbia, MO;
Dallas,TX;Miami,FL;NewYork,NY;LosAngeles,CA;San
Francisco, CA; Portland, OR; Chattanooga, TN; Atlanta, GA;
Lawrence, MA; Glendale, CA). In each survey, recruitment was
conducted on the basis of minimum cell sizes for each sex in
specific age bands, stratified further by SES (education and
income criteria) and ethnicity. Cell sizes were calculated to
estimate mean height in each cell with a confidence interval of
1 cm, equivalent to a standard error of 0.5 cm. Participants
signed a consent form allowing use of their anonymized
data in statistical analyses. Ethical approval for analysis of the
data for medical purposes was granted by the Ethics Committee
of Great Ormond Street Hospital NHS Trust and the Institute
of Child Health, London.
For participants in SizeUSA, data were available on
duration of schooling and income. Income was classified
according to the following categories in ascending order:
oUSD25k, USD25–50k, USD50–75k, USD75–100k, 4USD100k.
The duration of schooling was categorized as ‘less high
school’, ‘high school’, or ‘college’. Age was categorized in
both samples into six groups: 18–25.99; 26–35.99; 36–45.99;
46–55.99; 56–65.99; X66 years. Overweight and obesity
were categorized using BMI cutoffs of 25 and 30 kg/m
2
respectively.
Whole body scans were obtained using a [TC]
2
scanner
(Cary, NC, USA; www.tc2.com), with the subject standing
motionless wearing close-fitting underwear. The manufac-
turer’s software automatically extracts key body landmarks
and uses these to determine a variety of girths and distances.
For our analyses, we used the girths of the mid-upper arm,
bust (women only), chest, waist, hips and mid-thigh.
Technical precision of all measurements was within 0.5 cm.
For further details, see our previous report on SizeUK.
20
General linear models were constructed to compare the
mean values of different populations or ethnic groups,
adjusting for confounders as appropriate. Owing to differ-
ences in purchasing power and educational systems between
the United Kingdom and the United States, the comparison
of whites between these populations was not adjusted for
income or education. However, use of the same recruitment
strategy in both populations ensured that the social
composition of the samples was equivalent. Comparisons
between ethnic groups within the United States were
adjusted for education and income. The body shape of white
Americans was assessed using white British as the reference
group. Numbers of non-white adults in SizeUK were too few
within some age groups for effective statistical analysis,
hence only data on white British individuals were considered
here. The body shape of African or Hispanic Americans was
assessed using white Americans as the reference group.
Scheffe’s post hoc test was used to describe the increase or
reduction in each anthropometric variable attributed to the
group under investigation.
Previous studies have often used ratios of girths to describe
body shape in more detail. For example, the waist–hip ratio
is often calculated to adjust the abdominal circumference for
physique. Such ratios offer a convenient approach for
routine clinical application, but may not be optimal for
large-scale statistical analyses. Many ratios are statistically
flawed, since dividing one variable by another does not
necessarily achieve an appropriate adjustment of the
numerator for the denominator, as discussed previously.
22
The approach we adopted was as follows. First, girth data
were log-transformed using natural logarithms. When multi-
plied by 100, the resulting coefficients are equivalent to the
percentage difference between groups.
23
Second, selected
girths were adjusted for a further girth (for example, waist for
hip) in the linear models.
We investigated several indices of body shape using this
general approach. Waist girth was adjusted for hip girth,
Body shape in American and British adults
JCK Wells et al
153
International Journal of Obesity

thigh girth and in women, bust girth. Thigh girth was
adjusted for hip girth and arm girth. Collectively, these
analyses indicate relative distributions of weight across the
torso and limbs.
Results
Raw data for SizeUK and SizeUSA are given in Table 1. Rates
of obesity were significantly greater in African and Hispanic
Americans, especially African-American women, than in
white Americans. Obesity rates were around 10% lower in
white British than in white Americans.
For SizeUSA, Table 2 shows associations between indices of
social status (income and education categories) and either
height or waist girth adjusted for height and hip girth, all
data further adjusted for age category and whichever of
income or education was not the dependent variable. In
white and Hispanic Americans, increasing social status was
directly associated with height. The equivalent associations
were not apparent in African Americans. In white and
African Americans, increasing social status was inversely
associated with waist girth, except for income status in
African-American males. In Hispanic Americans, waist
girth was inversely associated with education level but
not income.
Table 3 presents comparisons of white men and women
from the United Kingdom and the United States. In both
sexes, after adjusting for age and height, Americans had
significantly greater weight, BMI and girths than their UK
counterparts. However, when waist girth was adjusted for
hip or thigh girth, the between-country difference varied by
gender. American white men had larger waist relative to
physique than UK white men, whereas American white
women had smaller waist girth than UK white women.
American white men had larger thigh girth, even after
adjusting for hip girth, whereas in women there was no
difference after adjusting for hip girth. American white men
had larger arm girth, while thigh girth adjusted for arm girth
did not differ between the populations. In contrast,
American white women had smaller thigh relative to arm
girth. These between-country differences are summarized
in Figure 1.
Table 4 presents comparisons of African or Hispanic
Americans against white Americans, adjusting for age,
income, education and (where relevant) height. African
Americans were similar in height to white Americans, but
had greater BMI. African-American women had larger girths
than their white counterparts, however African-American
men had smaller waist girth but greater arm and thigh girth.
Taking into account physique, African-American men had
smaller waist relative to hip or thigh, and larger thigh
relative to arm. African-American women had smaller waist
relative to thigh, but smaller thigh relative to arm. This sex
difference in thigh–arm ratio could be attributed to the
much greater increase in arm girth of African Americans
Table 1 Description of adults in SizeUK and SizeUSA
SizeUK SizeUSA
White White African American Hispanic American
Men Women Men Women Men Women Men Women
NNNNNNNN
Total sample 3907 4710 1746 3329 709 1106 639 839
Income 4$25k 484 692 397 379 409 472
$25k-50k 373 862 164 401 141 232
$50k-75k 332 701 81 160 43 69
$75k-100k 223 469 29 69 14 25
4$100k 283 471 15 52 16 70
Education less high school 64 77 48 42 138 152
High school 333 534 287 254 243 265
College 1346 2716 372 806 250 418
Prev. overweight (%) 38.8 27.3 40.7 27.0 37.2 28.2 40.4 34.3
a
Prev. obesity (%) 13.7
a
13.7
a
23.6 21.3 27.5
a
40.0
a
29.9
a
28.2
a
Mean s.d. Mean s.d. Mean s.d. Mean s.d. Mean s.d. Mean s.d. Mean s.d. Mean s.d.
Weight (kg) 80.3 13.4 66.8 13.2 86.0 16.9 70.2 16.6 86.9 18.9 79.0 20.6 81.2 16.2 68.8 14.6
Height (m) 1.77 0.08 1.63 0.07 1.78 0.08 1.64 0.07 1.77 0.08 1.64 0.07 1.70 0.08 1.58 0.07
BMI (kg/m
2
) 25.7 4.0 25.0 4.8 27.3 5.1 26.2 6.0 27.9 5.9 29.3 7.3 28.0 5.1 27.4 5.8
Arm (cm) 31.1 3.6 28.8 4.2 33.6 4.1 30.5 4.9 34.5 4.6 33.1 5.9 33.0 4.0 30.8 4.5
Chest (cm) 107.1 8.4 95.0 8.8 109.8 9.3 97.7 10.4 109.2 10.0 101.0 12.0 109.0 9.3 99.5 10.2
Waist (cm) 94.9 11.5 87.4 11.6 97.8 13.7 88.4 13.7 95.0 15.1 92.7 16.2 96.5 13.2 90.1 13.0
Hip (cm) 103.2 7.2 104.1 9.9 104.8 9.7 107.4 12.6 104.1 11.7 111.9 14.6 103.1 9.7 106.8 11.4
Thigh (cm) 48.5 4.2 49.2 4.9 50.2 4.6 50.5 5.8 51.7 5.6 55.3 7.2 49.6 4.6 50.1 5.2
Bust (cm) FF99.0 10.3 FF103.0 12.3 FF107.4 14.4 FF105.1 11.9
Abbreviations: BMI, body mass index. Prev. ¼ prevalence; N ¼ number; s.d. ¼ standard deviation.
a
Significant difference compared to white Americans.
Body shape in American and British adults
JCK Wells et al
154
International Journal of Obesity

relative to white Americans in women compared to men.
Hispanic Americans were shorter than white Americans, and
had greater BMI. They had larger girths, except of the thigh.
Taking into account physique, Hispanic Americans had
greater waist relative to hip or thigh, or bust in women. In
Hispanic women, but not men, thigh girth was smaller
relative to the arm. The differences relative to white
Americans are summarized in Figure 2 for males and Figure 3
for females. These figures illustrate that female Hispanics and
African Americans tend to differ from their white counter-
parts in similar directions, but with different magnitudes. In
contrast, male Hispanics and African Americans tend to
differ from their white counterparts in both direction and
magnitude.
Discussion
Our analyses have revealed significant differences in size and
body shape between ethnic groups and social categories
within the US population, and have further demonstrated
significant differences in body shape between US and UK
white adults. These differences may prove to play a key role
in accounting for differences in morbidity and mortality
between these populations and social groups.
A substantial body of evidence now links the increasing
prevalence of obesity in industrialized populations with an
Table 2 Associations between social status and height or waist girth in white, African and Hispanic Americans
White African American Hispanic American
Men Women Men Women Men Women
N HT WG N HT WG N HT WG N HT WG N HT WG N HT WG
Income
1 484 1.74 98.6 692 1.61 91.5 397 1.75 98.0 379 1.64 96.7 409 1.67 97.5 472 1.58 93.1
2 373 1.75 98.4 862 1.62 90.9 164 1.74 97.4 401 1.63 95.2 141 1.69 97.6 232 1.59 92.7
3 332 1.76 97.8 701 1.63 90.4 81 1.75 97.4 160 1.64 95.7 43 1.70 96.3 69 1.60 92.5
4 223 1.76 96.7 469 1.63 90.1 29 1.75 97.0 69 1.62 94.8 14 1.66 98.4 25 1.60 92.3
5 283 1.77 96.9 471 1.63 89.3 15 1.73 96.0 52 1.63 93.1 16 1.70 96.7 17 1.63 90.6
P for trend o0.001 o0.001 o0.001 o0.001 0.9 0.2 0.8 o0.005 o0.005 0.6 o0.005 0.5
Education
1 64 1.73 99.5 77 1.60 91.4 48 1.75 97.2 42 1.62 95.3 138 1.68 99.1 152 1.57 92.3
2 333 1.76 99.4 534 1.62 89.3 287 1.77 96.7 254 1.64 94.8 243 1.70 98.7 265 1.59 91.5
3 1346 1.77 98.5 2716 1.64 88.6 372 1.77 95.7 806 1.64 93.2 250 1.71 97.7 418 1.60 91.0
P for trend o0.001 o0.05 o0.001 o0.001 0.4 0.06 0.8 o0.005 o0.002 o0.005 o0.001 0.09
N ¼ number; HT ¼ height; W ¼ waist girth. All analyses adjusted for age category, and either income or education category as appropriate. Waist girth also adjusted
for height and hip girth. Income classified as 1 ¼ oUSD25k, 2 ¼ USD25-50k, 3 ¼ USD50-75k, 4 ¼ USD75-100k, or 5 ¼ 4USD100k Duration of education categorized
as 1 ¼ less high school, 2 ¼ high school or 3 ¼ college.
Table 3 Differences in shape between white adults from SizeUK and
SizeUSA, expressed as % difference of Americans relative to their UK
counterparts
Outcome US men (n ¼ 1746) P US women (n ¼ 3329) P
Difference s.e. Difference s.e.
BMI 5.8 0.5 o0.0001 3.7 0.4 o0.0001
Waist adj hips 1.0 0.2 o0.0001 2.3 0.1 o0.0001
Waist adj thigh 0.7 0.3 o0.02 1.1 0.2 o0.0001
Waist adj bust FFF 3.1 0.1 o0.0001
Thigh adj hips 2.0 0.2 o0.0001 0.2 0.1 0.10
Thigh adj arm 0.5 0.2 0.11 0.9 0.1 o0.0001
Abbreviation: BMI, body mass index. All outcomes adjusted for age and
(except BMI) height. Waist or thigh further adjusted (adj) for a second girth as
specified. US men and women compared against 3907 UK men and 4710 UK
women.
87
6
54
3
210
Weight
Thigh
Hip
Waist
Bust
Chest
Arm
Height
US White men
US White women
% difference relative to UK whites
**
**
**
**
**
**
*
**
**
**
**
**
**
Figure 1 Percentage difference in height, body girths and weight of white
American men and women relative to white British men and women. All
outcomes (except height) adjusted for height *Po0.01; **Po0.0001.
Body shape in American and British adults
JCK Wells et al
155
International Journal of Obesity

increased burden of disease, especially in relation to the
metabolic syndrome.
2,3
However, what is less clear is the
extent to which variability in the prevalence of obesity can
account for variability in morbidity and mortality in relation
to SES and ethnicity.
A major factor hindering investigation of this issue has
been the use of a crude approach to categorizing obesity.
While standardized cutoffs for obesity facilitate broad
between-population comparisons, BMI provides only a poor
proxy for the central fat mass most strongly associated with
disease risk. BMI has undoubtedly been of value in predicting
morbidity and mortality within populations, and within any
ethnic group, high levels of BMI are associated with poorer
health. However, individuals within and between ethnic
groups differ in their regional distribution of excess weight,
hence BMI is confounded by variability in physique and
remains a relatively crude index of risk. For example, Asians
are now known to have both greater disease risk
24–26
and
greater body fatness
27
than Europeans for any given BMI
level, which has led to proposals for ethnic-specific BMI
cutoffs to identify overweight and obesity.
13
In our own
analyses, population differences in BMI did not match those
in body shape. For example, whereas African-American men
were significantly heavier than their white counterparts,
their waist girth was smaller and their thigh girth larger.
Hispanic men and women had lower rates of obesity
according to BMI compared to African Americans, but had
larger waist and smaller thigh girth.
A large study of data from 52 countries demonstrated
markedly greater sensitivity of the waist–hip ratio compared
to BMI in predicting myocardial infarction.
16
However, these
measurements may themselves not be the most sensitive
indicator of risk. Several recent studies of adults have found
that sagittal diameter is a superior predictor of cardiovascular
risk, risk of the metabolic syndrome and mortality.
28–31
This
may be attributed to the fact that sagittal diameter is likewise
more closely associated with visceral fat than waist circum-
ference.
32,33
Other studies suggest that certain fat depots
may be protective against disease risk. In a case–control
study of ischemic heart disease, the ratio of sagittal diameter
Table 4 Differences between ethnic groups in SizeUSA, expressed as % difference compared to US whites
Outcome African American Hispanic American
Men (n ¼ 709) Women (n ¼ 1106) Men (n ¼ 39) Women (n ¼ 839)
Diff s.e. P Diff s.e. P Diff s.e. P Diff s.e. P
BMI 2.3 0.9 o0.01 11.1 0.8 o0.0001 4.1 0.9 o0.0001 4.4 0.9 o00001
Waist adj hip 2.6 0.3 o0.0001 0.2 0.2 0.4 0.6 0.3 o0.05 1.8 0.3 o0.0001
Waist adj thigh 6.2 0.4 o0.0001 3.4 0.4 o0.0001 1.7 0.5 o0.0005 3.0 0.4 o0.0001
Waist adj bust FF F 0.3 0.2 0.09 FF F 0.5 0.2 o0.05
Thigh adj hips 3.2 0.2 o0.001 4.7 0.2 o0.0001 0.4 0.3 0.15 0.9 0.2 o0.0002
Thigh adj arm 1.1 0.3 o0.0001 -3.1 0.2 o0.0001 0.3 0.3 0.2 1.5 0.3 o0.0001
Abbreviations: BMI, body mass index. Diff ¼ mean difference. All outcomes adjusted for age, income and education categories, and (except BMI) height. Waist or
thigh further adjusted (adj) for a second girth as specified. African and Hispanic Americans compared against 1744 white US men and 3329 white US women.
543210–1–2–3–4
Weight
Thigh
Hip
Waist
Bust
Chest
Arm
Height
African Americans
Hispanic Americans
% difference relative to White Americans
**
*
**
**
*
**
*
**
*
*
Figure 2 Percentage difference in height, body girths and weight of African
and Hispanic American men relative to white American men. All outcomes
adjusted for age, income and education categories and (except height)
height. *Po0.01; **Po0.001.
131197531–1–3
Weight
Thigh
Hip
Waist
Bust
Chest
Arm
Height
African Americans
Hispanic Americans
% difference relative to White Americans
**
**
**
**
**
**
**
**
**
*
**
**
**
**
Figure 3 Percentage difference in height, body girths and weight of African
and Hispanic American women relative to white American women. All
outcomes adjusted for age, income and education categories and (except
height) height. *Po0.05; **Po0.001.
Body shape in American and British adults
JCK Wells et al
156
International Journal of Obesity

to thigh girth was the strongest positive predictor of risk,
while thigh girth was negatively predictive.
17
Other studies
have likewise found sagittal diameter adjusted for thigh girth
to be the strongest predictor of cardiovascular disease,
34
and
confirmed the protective association of thigh adiposity with
cardiovascular risk
18,35
and type 2 diabetes.
19
Within Americans, our analyses showed that increasing
social status, as represented by income or years of education,
was broadly associated with greater height and a
smaller waist girth adjusted for hip girth. However,
African Americans did not show such associations for
height, while Hispanic Americans did not show such
associations for education level and waist girth. The lack of
such associations may be due to insufficient time having
elapsed for improvements in living conditions and opportu-
nities to impact fully on growth. Both short stature and
central adiposity are associated with poor growth patterns in
early life, implying that improved circumstances need to
persist over generations to confer significant benefits on the
current generation. A further factor may have been the small
numbers of African- and Hispanic Americans in high-income
categories, reducing the statistical power for detecting
associations with shape. Nevertheless, the broad presence
of such trends demonstrates the importance of adjusting for
socio-economic variables when comparing body shape
between ethnic groups, and furthermore indicates the
importance of social environmental factors in exposure to
the obesogenic environment. Although studies on this issue
are rare in the United States,
36
a recent analysis demon-
strated increasing disparity in life expectancy between rich
and poor Americans.
37
Our comparison of white adults from the United Kingdom
and United States revealed a sex difference. American
males had greater waist circumference than British men,
whether or not adjusted for hip or thigh girth. In contrast,
American women had smaller waist girth than British
women after adjusting for hip or thigh girth, although
they had greater absolute waist, hip and bust girths,
4% greater BMI and 10% greater prevalence of obesity
categorized by BMI. It is probable therefore that the reduced
hip-adjusted waist girth does not imply reduced cardio-
vascular risk in the US white women, and is rather simply
an artefact of their excess weight being located in hips
and bust as well as waist. Consistent with this assumption,
there was no sex difference in markers of ill-health in the
previous between-country analysis of morbidity (Marmot M,
personal communication).
Our findings in relation to ethnic groups within the
American population show some consistency with the
results of the third National Health and Nutrition Examina-
tion Survey, which found that African Americans had
slightly lower prevalence of the metabolic syndrome
than whites, while Mexican Americans had the highest
prevalence.
38
Underlying these overall trends, however,
individual components of the metabolic syndrome showed
more dramatic differences, with white and Mexican Amer-
icans having significantly higher rates of hypertriglyceride-
mia and low high density lipoprotein concentration,
whereas African Americans had higher rates of hyperten-
sion.
38
More detailed studies have revealed ethnic differ-
ences in the amount of visceral fat present at a given
waist circumference, and in the metabolic activity of
this fat depot. For example, African Americans have been
found to have lower absolute levels of visceral adiposity
39–41
but to be relatively more insulin resistant nonetheless.
11
Despite their apparently healthier shape, especially in males,
African Americans show the highest incidence of cardiovas-
cular disease.
7,8
Ethnic variability in the physiological
impact of abdominal versus peripheral fat depots on
metabolic risk therefore needs to be taken into account,
and our data on body shape match more closely with the
ethnic distribution of the metabolic syndrome than with
that of cardiovascular mortality.
The inter-relationships between ethnicity, body shape and
risk of disease are therefore complex. Collectively, our
findings highlight the potential for 3D body scanning to
contribute to the categorization of risk and the monitoring
of patients, in particular addressing ethnic differences in
physique and physiology. Providing a wealth of information
about body shape at a fraction of the cost of MRI scanning,
3D photonic scans combined with ethnic-specific reference
data have the potential to identify those at high risk of the
metabolic syndrome, and to track the response of such
individuals to treatment.
In summary, analyses of two large surveys of body shape
using 3D photonic scanning have shown significant differ-
ences between nations in a single ethnic group, and
significant differences within a nation between groups
categorized according to social status or ethnicity. The
pattern of variability in body shape closely tracks the pattern
of variability in incidence of the metabolic syndrome,
implicating central abdominal fat as an important contribut-
ing factor to health disparities. Detailed measurement of
body shape, using ethnic-specific reference data, therefore
has the capacity to improve the categorization of risk of the
metabolic syndrome, and could potentially prove equally
valuable for monitoring response to treatment.
Acknowledgements
JW analyzed the data with TC, and wrote the first draft of the
manuscript. PT directed SizeUK, and DB directed SizeUSA. PT
and DB extracted appropriate data and advised on analyses.
All authors contributed to revising the manuscript. PT is the
director of Bodymetrics, a company specializing in 3D
applications for the clothing industry. DB is vice president
of [TC]
2
, a non-profit organization that uses 3D scanning
instrumentation in clothing applications.
This work uses data from Sizing Surveys funded by
Retailers and the UK Department of Trade and Industry.
Body shape in American and British adults
JCK Wells et al
157
International Journal of Obesity

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