Journal of Public Health | Vol. 30, No. 2, pp. 139 –144 | doi:10.1093/pubmed/fdn013 | Advance Access Publication 3 March 2008
Trends in overweight and obesity among 5 –7-year-old White
and South Asian children born between 1991 and 1999
Ravikumar Balakrishnan1, Premila Webster1, Don Sinclair2
1
Department of Public Health, University of Oxford, Old Road, Headington, Oxford OX3 7LF, UK
Berkshire East Primary Care Trust, Beech House, Upton Hospital, Albert Street, Slough SL1 2BJ, UK
Address correspondence to Premila Webster, E-mail: [email protected]
2
A B S T R AC T
Objective To determine the trends in overweight and obesity among White and South Asian children aged 5–7 years born between 1991 and
1999 and included in the East Berkshire Child Health System.
Methods Children were grouped into nine cohorts based on their year of birth. The UK National BMI percentile classification was used to classify
the children as overweight and obese and to examine the prevalence and trends by year of birth, sex and ethnicity.
Results Overall, more boys (10.1%; 9.7–10.6%) than girls (9.1%; 8.7–9.6%) were obese (P , 0.003). South Asian boys were more likely to be
overweight (OR 1.92; 95% CI 1.62–2.28; P , 0.01) and obese (OR 1.53; 95% CI 1.28– 1.89; P , 0.01) than South Asian girls. Overweight (1.77;
1.56–2.00; P , 0.05) and obesity (1.76; 1.50– 2.06; P , 0.05) were significantly higher among South Asian boys compared with their White
counterparts (baseline). After adjusting for sex, ethnicity and year of birth, South Asian children were 27% more overweight (P , 0.01) and 45%
more obese (P , 0.01) compared with White children, and boys were 6% more overweight (P ¼ 0.04) and 12% more obese (P ¼ 0.003)
compared with girls. There was an increasing trend in overweight among boys (P ¼ 0.01) and girls (P ¼ 0.003); and in obesity among boys
(P , 0.001) and girls (P ¼ 0.008) in children born from 1991 to 1999.
Conclusion There is a significant rise in childhood obesity among 5– 7-year-old children. Overweight and obesity among South Asian boys are
significantly higher than that among South Asian girls. This group may be at greater risk of morbidity and mortality related to obesity and may
need to be targeted appropriately for interventions to reduce obesity.
Keywords childhood obesity, South Asian, trends
Introduction
Childhood obesity has reached epidemic levels in developed
countries. Between 1984 and 1998, prevalence of overweight
between 7 – 11-year olds in the UK rose from 8 to 20%.1
Between 1995 and 2003, the prevalence of obesity among
children aged 2 –10 in the UK rose from 9.9 to 13.7%.2
A rise in childhood obesity is of particular concern as childhood and adolescent obesity predisposes to obesity in adulthood.3,4 There appears to be a variation in obesity by ethnic
groups. In the United States, a large variation in childhood
obesity by ethnic groups was shown.5 Over a 30-year
period, the prevalence of overweight increased 3-fold
(4–13%) among 6–11-year-old White children, but 5-fold (4–
20%) among Black children. In most gender-age groups,
Mexican-American children experienced increases in overweight
that were between those experienced by Blacks and Whites.
Differences between ethnic groups were less marked among
2 –5-year olds, and in this age group, White children experienced the largest increase in overweight (from 4 to 9%).6
Between 1999 and 2002, the prevalence of extreme obesity,
BMI levels (99th percentile) reached 6 –7% among Black
girls and Mexican-American boys.6 Ethnic differences in the
prevalence of overweight and obesity among children at
school entry have been reported in the UK.7 – 9 However,
there were no reports assessing the trend. British South
Asian children were reported to have higher cardiovascular
risk compared with White children.10 An understanding of
Ravikumar Balakrishnan, Specialist Registrar
Premila Webster, Hon. Senior Lecturer
Don Sinclair, Director of Public Health
# The Author 2008, Published by Oxford University Press on behalf of Faculty of Public Health. All rights reserved
139
140
J O U RN A L O F P U B L I C H E A LTH
the trend and prevalence of obesity and overweight in
children in this age group is important to develop effective
public health interventions.
Table 1 Demographic characteristics of study population (N ¼ 51 565)a
Height and Weight data
Method
Participants
There were 51 565 children born between January 1991 to
December 1999 in East Berkshire and included in the Child
Health Information System. Among them, 29 641 children
with height and weight data measured by school nurses in
year 1 (5 –7 years old) were included in this study.
Total
Height and weight were measured at school, by school
nurses (trained in collecting height and weight) for all children at school entry (year 1) every year. Children’s height
was measured in centimeters (to the nearest half centimeter)
without shoes using stadiometers. Children’s weight was
measured in kilograms, to the nearest 100 g unit (0.1 kg)
with normal indoor clothing without shoes using mechanical
scales (calibrated annually).
Children were grouped into nine cohorts based on their
year of birth. The UK National BMI percentile classification11 was used to classify the children as overweight and
obese, and we examined for trends by year of birth, sex and
ethnicity. Actual date of birth was used to calculate the age
of the children at the time of measurement of height and
weight. BMI was calculated from the height and weight data
using the formula BMI 5 weight (kg)/height (m2).
Statistical analysis
STATA (version 10) package was used for statistical analysis.
The outcome measures were overweight (.85th percentile)
and obesity (.95th percentile) BMI percentile cut-offs of
the UK reference data.11 Pearson’s x2-test was used to test
the statistical significance of differences in proportions.
Mantel-Haenszel’s x2-test for linear association was used to
investigate trends in the prevalence rates over the study
period. Prevalence odds ratio (POR) was calculated as
obesity is a chronic condition and its risk factors like ethnicity and sex are long-lasting. Multiple logistic regression
models for overweight and obesity with sex, ethnicity and
birth year as explanatory variables were used. P-values (twosided) of ,0.05 were considered statistically significant.
Missing
Number % (95% CI)
Number % (95% CI)
29 641
21 924
57.5
42.5
Gender
Boys
15 163
51.2 (50.6 –51.7) 11 200
51.1 (50.4 –51.7)
Girls
14 478
48.8 (48.3 –49.4) 10 724
48.9 (48.3 –49.6)
Ethnicity
White
South Asian
Afro-Caribbean
Measuring obesity in children
Available
13 116
80.2 (79.5 –80.8)
6431
79.4 (78.5 –80.2)
3025
18.5 (17.9 –19.1)
1542
19.1 (18.3 –20.0)
223
1.4 (1.2– 1.6)
120
1.5 (1.2 –1.8)
a
Total number of children born between 1991 and 1999, recorded in the
East Berkshire Child Health System.
Results
Height and weight data were available for 29 641 (57.5%) of
the 51 565 children born between January 1991 and
December 1999 in East Berkshire and registered in Child
Health Information System. Table 1 shows that the nonresponders (i.e. children without height and weight data) did
not differ significantly from those who have, either by sex
(P ¼ 0.88) or ethnicity (P ¼ 0.40).
Prevalence of overweight and obesity by sex
and ethnicity
Table 2 shows the prevalence of overweight and obesity
among 5 –7-year-old children born between 1991 and 1999
by sex and ethnicity. Overall, boys were significantly more
obese than girls (10.1 versus 9.1%; P , 0.003). Table 3
shows the unadjusted POR for factors affecting prevalence
of overweight and obesity by sex and ethnicity. Initially girls
were taken as the baseline category and POR was calculated
overall and for each ethnic category. South Asian boys were
more likely to be overweight (OR 1.92; 95% CI 1.62 –2.28;
P , 0.01) and obese (OR 1.53; 95% CI 1.28 –1.89;
P , 0.01) than South Asian girls. There were no significant
differences in obesity and overweight between boys and girls
either in White or Afro-Caribbean ethnic groups. Then POR
was calculated for South Asian and Afro-Caribbean children
with White children as the baseline category. Overweight
(1.77; 1.56 –2.00; P , 0.05) and obesity (1.76; 1.50 –2.06;
P , 0.05) were significantly higher among South Asian boys
compared with those among their White counterparts.
141
TR EN D S I N CH IL D H O O D O BE SI TY
Table 2 Prevalence of overweight and obesity among 5 –7-year-old
children born between 1991 and 1999 by gender and ethnicity
Gender Ethnicity
% (95% CI)
Overweight
factors including sex, ethnicity and year of birth. After
adjusting for other factors in the table, overweight and
obesity were significantly higher among boys and South
Asian children.
Obese
including obese
Total
White (n ¼ 13 116)
20.7 (20.0 – 21.4)
9.7 (9.2 –10.2)
South Asian (n ¼ 3025)
25.0 (23.5 – 26.6)
13.6 (12.4 – 14.8)
Afro-Caribbean (n ¼ 223) 24.7 (19.2 – 30.9)
Girls
Boys
10.8 (7.0 –15.6)
Unrecorded (n ¼ 13 277)
19.1 (18.4 – 19.8)
8.7 (8.2 –9.1)
Total (n ¼ 29 641)
20.4 (20.0 – 20.9)
9.6 (9.3 –10.0)
White (n ¼ 6460)
21.3 (20.3 – 22.3)
9.7 (9.0 –10.5)
South Asian (n ¼ 1484)
18.9 (16.9 – 21.0)
11.1 (9.5 –12.8)
Afro-Caribbean (n ¼ 108) 24.1 (16.4 – 33.3)
10.2 (5.2 –17.5)
Unrecorded (n ¼ 6426)
18.8 (17.9 – 19.8)
Total (n ¼ 14 478)
20.0 (19.3 – 20.6)
9.1 (8.7 –9.6)
White (n ¼ 6656)
20.1 (19.2 – 21.1)
9.7 (9.0 –10.5)
South Asian (n ¼ 1541)
30.9 (28.6 – 33.3)
16.0 (14.2 – 17.9)
Afro-Caribbean (n ¼ 115) 25.2 (17.6 – 34.2)
8.1 (7.4 –8.8)
11.3 (6.2 –18.6)
Unrecorded(n ¼ 6851)
19.3 (18.4 – 20.3)
9.2 (8.5 –9.9)
Total (n ¼ 15 163)
20.9 (20.3 – 21.6)
10.1 (9.7 –10.6)
However, overweight among South Asian girls (0.86; 0.75–0.99;
P , 0.05) was significantly lower than that among their
White counterparts. Table 4 shows the adjusted prevalence
odds ratio (aPOR) for multiple logistic regression models of
Trends in overweight and obesity by sex
and ethnicity
Proportion of overweight children increased significantly
among boys (x2 linear trend ¼ 6.39, P ¼ 0.01) and girls
(x2 linear trend ¼ 8.55, P ¼ 0.003) for those who were
born in 1991 –99. A similar increase in trend was also
shown for obesity in boys (x2 linear trend ¼ 12.77, P ,
0.001) and girls (x2 linear trend ¼ 7.02, P ¼ 0.008)
(Fig. 1).
Among the 29 641 children, ethnicity details were
recorded for 16 364 (55%). The proportion of boys (51.2%,
95% CI 50.6 –51.7) and girls (48.8%, 95% CI 48.3 –49.4)
with ethnicity recorded was similar to the proportion (boys
51.1%, 95% CI 50.4 – 51.7) and girls (48.9%, 95% CI 48.3 –
49.6) with ethnicity unrecorded.
Owing to small number of children with ethnicity
recorded in 1991, data for that year was omitted in the
trend analysis by ethnicity. Overweight and obesity appear to
increase over the years in both White and South Asian
groups but more steeply in the latter though the trends are
not statistically significant (Fig. 2).
Table 3 Unadjusted POR for factors affecting prevalence of overweight and obesity among 5– 7-year-old children in East Berkshire by sex and ethnicity
Unadjusted PORa (95% CI)
Overweight (including obese)
Girls
Boys
1
0.94 (0.89 –1.00)
White (n ¼ 13 116)
1
South Asian (n ¼ 3025)
1
Afro-Caribbean (n ¼ 223)
Unrecorded (n ¼ 13 277)
Obese
Girls
Boys
0.44
1
0.89 (0.82 – 0.96)
0.93 (0.86 –1.02)
0.12
1
1.00 (0.89 – 1.13)
0.95
1.92 (1.62 –2.28)
,0.01
1
1.53 (1.23 – 1.90)
,0.01
1
1.06 (0.55 –2.05)
0.84
1
1.12 (0.45 – 2.85)
0.78
1
0.97 (0.89 –1.06)
0.48
1
0.87 (0.77 – 0.99)
0.026
White (n ¼ 13 116)
1
1
1
1
South Asian (n ¼ 3025)
0.86 (0.75-0.99)a
1.77 (1.56 –2.00)a
1.16 (0.96 –1.39)
1.76 (1.50 – 2.06)a
Afro-Caribbean (n ¼ 223)
1.17 (0.75-1.83)
1.34 (0.87 –2.04)
1.05 (0.56 –1.98)
1.18 (0.66 – 2.12)
Unrecorded (n ¼ 13 277)
0.86 (0.79-0.94)a
0.95 (0.87 –1.03)
0.82 (0.73 –0.93)a
0.94 (0.83 – 1.05)
Totalb (n ¼ 29 641)
P-value
P-value
0.004
Ethnicityb
Ethnicityc
a
POR: prevalence odds ratio.
b
c
Girls as reference category.
White children as reference category; a ¼ p , 0.05.
142
J O U RN A L O F P U B L I C H E A LTH
Table 4 aPOR for multiple logistic regression model of factors affecting prevalence of overweight and obesity among 5– 7-year-old children in East
Berkshire
Overweight (including obese)
Adjusted PORa (95% CI)
Obese
P-value
Adjusted POR (95% CI)
P-value
Sex
Girlsa
1
Boys
1.06 (1.002 – 1.123)
1
0.04
1.12 (1.04 –1.21)
0.003
Ethnicityb
Whitea (n ¼ 13 116)
1
South Asian (n ¼ 3025)
1.27 (1.16 –1.39)
,0.01
1.45 (1.28 –1.63)
,0.001
Afro-Caribbean (n ¼ 223)
1.24 (0.91 –1.68)
0.18
1.10 (0.72 –1.69)
0.66
Unrecorded (n ¼ 13 277)
0.93 (0.87 –0.99)
0.03
0.90 (0.82 –0.99)
0.03
1
Birth year
1991a
1
1992
0.94 (0.81 –1.09)
0.41
0.94 (0.76 –1.15)
0.54
1993
0.95 (0.82 –1.09)
0.45
0.88 (0.72 –1.07)
0.21
1994
1.10 (0.97 –1.25)
0.14
1.11 (0.93 –1.33)
0.23
1995
1.12 (0.99 –1.27)
0.06
1.11 (0.93 –1.32)
0.23
1996
1.14 (1.01 –1.29)
0.03
1.12 (0.94 –1.32)
0.21
1997
1.14 (1.01 –1.28)
0.04
1.20 (1.01 –1.41)
0.035
1998
1.12 (0.99 –1.27)
0.06
1.10 (0.93 –1.31)
0.25
1999
1.03 (0.91 –1.17)
0.68
1.06 (0.89 –1.27)
0.48
1
a
Reference category, baseline group for adjusted POR for categorical variables.
Discussion
Main finding of this study
The study shows a significant increase in childhood overweight and obesity among 5 –7-year olds, with the prevalence being higher in boys than girls. Among South Asian
children, boys are almost twice as likely to be overweight
and 1.5 times to be obese than girls.
What is already known on this topic
Overweight in children is a serious public health problem in
Britain.1,2 The incidence of childhood obesity is increasing
and likely to persist into adult life.3,4 Obesity results in considerable morbidity and mortality of which cardiovascular
disease is one of the principal causes.12,13 Migrant populations of South Asians living in the West are at a higher
risk of cardiovascular disease compared with the White
population.14 In the UK, ethnic differences in the prevalence of overweight and obesity among children at school
entry has been reported.7 – 9
What this study adds
There is a significant increase in childhood overweight and
obesity among 5 – 7-year-old born between 1991 and 1999.
The prevalence is higher in boys than in girls. The trend
increased more steeply in South Asian children, with South
Asian boys almost twice as likely to be overweight and 1.5
times to be obese as South Asian girls.
Limitations of this study
Different growth patterns in boys and girls at each age mean
that a universal categorization cannot be used to define
childhood obesity (as with adults). Each sex and age group
therefore needs its own level of classification for obesity.
This study uses the UK National BMI percentile classification to describe childhood overweight and obesity.11 This
gives the BMI threshold for each age and for boys and girls
separately above which a child is considered overweight or
obese. There are alternative methods for measuring childhood obesity, specifically an international classification developed by the International Obesity Task Force.15 There is an
ongoing debate regarding which classification of childhood
obesity is more robust. Using the UK National BMI percentile classification was considered appropriate for this study
as it provides a reference point that is derived from information about the UK population and is the method used in
the English Health Surveys.11
TR EN D S I N CH IL D H O O D O BE SI TY
143
Fig. 2 Trends in overweight and obesity (with 95% CI) among 5– 7year-old children by ethnicity and year of birth (1991 –1999).
Fig. 1 Trends in overweight and obesity (with 95% CI) among 5 –7year-old children by gender and year of birth (1991 – 1999).
Although the data were from children registered in East
Berkshire Child Health System, the catchment area covers a
diverse population ranging from the more deprived area of
Slough (deprivation score of 20.87) with a 28% South Asian
population to the affluent areas of Windsor and
Maidenhead (deprivation score of 8.22), with 4.6% South
Asians and Bracknell Forest (deprivation score of 8.61) with
1.9% South Asians.
Although the study shows that the non-responders (i.e. children without height and weight data) did not differ significantly from those who have, either by sex or ethnicity
socio-economic data were not collected as the children were
measured in primary school and it was not possible to collect
this data from the children. In addition, data collected did not
include independent schools. Although children who attend
state schools tend to be from a range of socio-economic backgrounds, the exclusion of independent schools (which would
almost exclusively have children from higher socio-economic
backgrounds) means that the impact of socio-economic status
on childhood obesity cannot be assessed in this study.
Overweight and obesity in childhood have a significant
effect on both physical and psychological health. South
Asians living in the west are at a higher risk of cardiovascular disease compared with the White population,14,16 – 18 and
a UK study estimating the prevalence of childhood type 2
diabetes and maturity onset diabetes of the young concluded
that South Asian children were at a significantly higher
risk.19 Evidence suggests that prevention could be the key
for controlling the current epidemic of obesity. Studies have
investigated general patterns of dietary change after
migration.19,20 Migrants tend to retain staple foods from
their own culture longest and introduce new foods selected
from the host culture based primarily on taste.19 Research
carried out to identify changes in the diet of a South Asian
transmigratory population collected data on dietary information on South Asian children aged 9 –11 in Bradford.21
The results suggest that novel sweet items were notably
introduced to the children’s diet in Bradford (e.g. breakfast
cereals and fizzy drinks), whereas traditional items (chapatti,
curry) persist.21 Research suggests that interventions should
focus on identifying at-risk and overweight children at an
144
J O U RN A L O F P U B L I C H E A LTH
early stage and educating families about the health consequences of being overweight.22 Young children are a priority group for intervention strategies and it is vital that
suitable interventions are targeted at appropriate groups to be
effective. South Asian children, especially boys, may be at
greater risk of morbidity and mortality related to overweight
and so may be a priority for specific initiatives identifying and
promoting healthy diets that are appropriate to South Asians,
culturally sensitive and target both the children and parents.
References
1 Lobstein TJ, James WP, Cole TJ. Increasing levels of excess weight
among children in England. Int J Obes Relat Metab Disord
2003;27:1136 – 8.
British South Asian
2002;324(7338):635.
and
white
children.
Br
Med
J
11 Jotangia D, Moody A, Stamatakis E et al. Obesity among children
under 11. Department of Health, NatCen, 2005, p. 20.
12 Dietz WH. Childhood weight affects adult morbidity and mortality.
J Nutr 1998;128:p411S – 4S.
13 Poirier P, Giles TD, Bray GA et al. Obesity and cardiovascular
disease: pathophysiology, evaluation, and effect of weight loss. An
update of the 1997 American Heart Association Scientific
Statement on Obesity and Heart Disease from the Obesity
Committee of the Council on Nutrition, Physical Activity, and
Metabolism. Circulation 2006;113;898 – 918.
14 Ismail J, Jafar TH, Jafary FH et al. Risk factors for non-fatal myocardial infarction in young South Asian adults. Heart
2004;90:259 – 63.
2 Jotangia D, Moody A, Stamatakis E et al. Obesity among children
under 11. Department of Health, NatCen. April 2005, p. 4.
15 Cole TJ, Bellizzi MC, Flegal KM et al. Establishing a standard definition for child overweight and obesity worldwide: international
survey. Br Med J 2000;320:1240 – 3.
3 Power C, Lake JK, Cole TJ. Body mass index and height from
childhood to adulthood in the 1958 British born cohort. Am J Clin
Nutr 1997;66(5):1094 – 101.
16 McKeigue PM, Miller GJ, Marmot MG. Coronary heart disease
in south Asians overseas: review. J Clin Epidemiol 1989;42:
597 – 609.
4 Guo SS, Wu W, Chumlea WC et al. Predicting overweight and
obesity in adulthood from body mass index values in childhood
and adolescence. Am J Clin Nutr 2002;76(3):653– 8.
17 Balarajan R. Ethnic differences in mortality from ischaemic heart
disease and cerebrovascular disease in England and Wales. Br Med J
1991;302:560– 4.
5 Rosner B, Prineas R, Loggie J et al. Percentiles for body mass index
in US children 5 to 17 years of age. J Pediatr 1998;132:211– 22.
18 Venkata C, Ram S. Hypertension and other cardiac risk factors
among Asian Indians. Am J Hypertens 1995;8:124s – 7s.
6 Freedman DS, Khan LK, Serdula MK et al. Racial and ethnic differences in secular trends for childhood BMI, weight, and height.
Obesity 2006;14(2):301 – 8.
19 Ehtisham S, Hattersley AT, Dunger DB et al. First UK survey of
paediatric type 2 diabetes and MODY. Arch Dis Child
2004;89:526 – 9.
7 Shaw NJ, Crabtree NJ, Kibirige MS et al. Ethnic and gender differences in body fat in British schoolchildren as measured by DXA.
Arch Dis Child 2007;92(10):872 – 5.
20 Wandel M. Nutrition-related diseases and dietary change among
third world immigrants in Northern Europe. Nutr Health
1993;9:117 – 33.
8 Jebb SA, Rennie KL, Cole TJ. Prevalence of overweight and obesity
among young people in Great Britain. Public Health Nutr
2003;7(3):461 – 5.
21 Edwards S, Murphy C, Feltbower RG et al. Changes in the diet of a
South Asian transmigratory population may be associated with an
increase in incidence of childhood diabetes. Nutr Res
2006;26(6):249– 54.
9 Chinn S, Hughes JM, Rona RJ. Trends in growth and obesity in
ethnic groups in Britain. Arch Dis Child 1998;78(6):513– 7.
10 Whincup PH, Gilg JA, Papacosta O et al. Early evidence of ethnic
differences in cardiovascular risk: cross-sectional comparison of
22 Fowler-Brown A, Kahwati LC. Prevention and treatment of overweight in children and adolescents. Am Fam Physician
2004;69(11):2591 – 8.