ORIGINAL

Niger J Paed 2014; 41 (3):194 –198

Nwaiwu O

Ibe BC

Body mass index of children aged

2

to 15 years in Enugu Nigeria

DOI:http://dx.doi.org/10.4314/njp.v41i3,8

Accepted: 10th February 2014

2

Abstract:

Background: Body

mean BMI of 16.28 + 2.32 kg/m .

Mass Index (BMI) is a measure

of adiposity and has been used

in many countries for assessment

of overweight and obesity. The

prevalence of obesity in children

is increasing and is recognized

as risk indicator of cardiovascu-

lar disease in adulthood. The

study aimed was to document the

Body Mass Index of school chil-

dren aged 2-15 years. The study

also determined the prevalence of

overweight and obesity.

The mean BMI for males was

16.09 + 2.07 and the females 16.47

+ 2.52. (P > 0.05). The preva-

lence of overweight and obesity

were 6.4% and 1.7% respectively.

More females were significantly

overweight than males (p<0.05).

Prevalence of overweight and

obesity were highest in the high-

est socioeconomic class.

(

)

Nwaiwu O

Department of Pharmacology,

Therapeutics & Toxicology

College of Medicine,

University of Lagos, Nigeria.

Email: obiyo_nwaiwu@yahoo.com

onwaiwu@unilag.edu.ng

Ibe BC

Department of Paediatrics,

University of Nigeria Teaching

Hospital Enugu, Nigeria.

Conclusion: Most children

had

BMI within the normal range. The

prevalence of overweight and

Methods: This is a descriptive

study of obesity prevalence in Ni-

gerian Children. The weight and

heights of the sampled children

were measured and their BMI

obesity

though predominantly

low should be taken seriously

especially as it appears to be

associated with improving socio-

economic status. School health

education (physical activity and

nutritional education) is recom-

mended as preventive measures.

was calculated as weight/height

2

(

m ). Overweight and obese chil-

dren were identified using charts

from pooled internationally ac-

cepted data age and sex specific cut

Key words: Body mass index,

overweight, obesity, Nigerian

children.

-off points for BMI .

Results: The BMI ran₂ged from

2.

0.8kg / m to24.7Kg/m with a

1

Introduction

childhood and adolescent obesity include glucose intol-

erance, hypolipidaemia, hypertension, gallstones and

pseudotumour cerebri. Childhood obesity has significant

impact on the emotional development of the child or

adolescent, who suffers discrimination and stigmatiza-

tion. They may have fewer opportunities in school, at

work and social circles. Individuals who were obese in

childhood are more likely to have poor body image, and

1

Billewicz et al in 1962 described for the first time in

detail the use of the body mass index as an index of

adiposity and is defined as weight (Kg) adjusted for

height (m) squared (weight/height ) in Kg/m . It is a

measure of adiposity , an index of weight corrected for

height. Body mass index correlates well with subcuta-

neous and total body fatness and has achieved interna-

tional acceptance as a standard for the assessment of

2

8

low self esteem and confidence .

3

obesity in both children and adults . BMI has been used

However there are different views on the criteria for

determining cut - offs for overweight and obesity . The

confusion over the use of different reference curves

led to the establishment of cut- offs based on pooled

in Nigeria and ma_,n₅_,y₆ countries for assessment of over-

4

weight and obesity . Overweight and obesity are con-

sidered an epidemic in many countries of the world in-

cluding developed and developing countries and its

health implications has become a matter of growing

9

data collected from international surveys. Cole et al

used pooled international data to develop age and sex

specific cut-off points for BMI to classify overweight

and obese children and this method can be conven-

iently applied to different populations and is simple to

use. The aim of this cross-sectional study was to docu-

ment the body mass index of school children aged 2-15

7

concern . The complications of childhood obesity in-

clude medical (mechanical or metabolic complications)

and psychosocial consequences. Mechanical complica-

tions include obstructive sleep apnoea syndrome and

orthopaedic problems. The metabolic consequences of

1

95

years and to determine the prevalence of overweight

and obesity using the i₉nternational cut-off thresholds

proposed by Cole et al

and sex specific cut off₉points for body mass index in

children and adolescents.

Table₉1: Age and sex specific international cut off points for

2

BMI

Age

BMI (kg/m )

(years)

Overweight

Boys

Obese

Boys

Subjects and Methods

Girls

This study was conducted in Enugu, the capital city of

Enugu state of Nigeria

2

3

4

5

18.4

17.9

17.8

17.4

17.6

19.1

19.8

20.0

21.2

21.9

22.8

23.3

23.9

24.5

25.0

18.0

17

20.1

19.6

19.3

19.8

22.8

24.0

25.7

26.0

26.8

27.8

28.3

28.9

29.4

30.0

20.1

19.4

19.1

19.2

19.7

22.8

24.1

20.4

26.7

27.8

26.6

29.1

29.4

29.7

30.0

The study was a prospective cross-sectional observa-

tional study in which a two stage systematic sampling

method was used. In the first stage, the schools were

selected while the students were selected in the second

stage.

17.3

17.1

17.3

19.1

19.9

20.7

21.7

22.6

23.3

23.9

24.4

24.7

25.0

6.

9

1

16.

17.

18.

.

0.

1.

2.

3.

4.

5.

Eighteen schools were selected from the sampling frame

using a sampling interval of 10. Every third child

received a questionnaire, letter of introduction and con-

sent form. The parents filled the questionnaires, answer-

ing questions concerning the child’s age and medical

history, occupation and educational status of the parents.

Two thousand questionnaires were distributed among

the students using a sample interval of three (the 18

schools had a population of 5250 students). Each school

was visited between 10 am and 1.30 pm each day. The

head teacher in each school and the investigator ex-

plained the study to the student before physical exami-

nation and anthropometry were done. Apparently

healthy school children (male and female) aged 2-15

years (both years inclusive) who obtained the consent of

their parents were included in the study and children

with chronic diseases were excluded by medical history

Social class determination for the subjects was done

using the socio-economic index scores designed by

Oyedeji .The data was analyzed using the statistical

package for social science (SPSS); windows version

1

3

1

0.0, Microsoft Excel 2000.Distributions were described

as mean and standard deviation. Approval for the study

was granted by the post primary schools management

board (permanent secretary’s office), Enugu State Pri-

mary Education Board, and the Education Secretaries of

the three local Government Education, Authorities.

Ethical clearance was obtained from the Ethical commit-

tee of the University of Nigeria Teaching Hospital

Enugu.

(

parental questioning) and by physical examination.

Anthropometric measurements

Standing height was measured once without shoes to the

nearest 0.5cm. He or she was asked or helped to stand

erect. The child’s heels were together; the buttocks, the

back of the heels, the upper back and the head touched

the wooden measuring tape. The movable horizontal

head-board was lowered until it rested firmly on the

crown of the head. The vertical tape measure was read

opposite the highest point of the head with the child

looking straight ahead. Weight was measured to the

nearest 0.1 kg using a bath room scale. The students

wore school uniforms (light clothing) without outer gar-

ments, sweaters and shoes. The scale was calibrated to

zero prior to the beginning of each session and checked

with a standard weight at the beginning of each day. The

investigator was assisted by a nurse who had been previ-

ously been trained on how to measure a child properly.

Two measurements were made per subject and the mean

was utilized in data analysis.

Results

The subjects in the study comprised four hundred and

six apparently healthy Nigerian school children. There

were 197 males and 209 females (male: female ratio of

1

: 1.06.).

The age distribution of the subjects is illustrated in fig-

ure 1. The ages ranged from 2 to 15 years with a mean

of 8.18+ 2.98 years. The mean age for males was 8.18

+

2.71 years while that of females was 8.71 + 3.20

years. The difference between the mean age for males

and that for females was not statistically significant. (P >

0

.05).

Fig 1: Age distribution of Subjects

Body mass index

The body mass index₃(quetelets’ index) was calculated

using the

BMI (Kg/m ) = Weight (Kg)

formulae

2

Height (m)

Overweight and obese subjects were identified using age

1

96

Fig 2 illustrates the mean body mass index in various

ages. The body mass index had a range of 10.84kg /

overweight and obesity in the different social is

presented in table 4.

2

.

2

m to24.70Kg/m . The mean body mass index was 16.28

The number of overweight females was greater than the

number of overweight males, while obesity was com-

moner amongst males. The difference was statistically

significant (P<0.05). The highest prevalence of over-

weight was in the 10years age groups while the highest

prevalence of obesity in the 3years age group. Seventeen

(65%) of overweight individuals and five (71%) of the

obese children belong to social class I. None of the

obese children belongs to social class V.

2

+

2.32 kg/m . The mean body mass index for males was

1

6.09 + 2.07 and the females 16.47 + 2.52. The differ-

ence in the mean body mass index for males and

females was not statistically significant (P > 0.05).

Fig 2: Mean BMI in various ages

Table 3: Prevalence of obesity and overweight in study

population by gender

Status

Male (N=197)

No.(%)

Female (N=209)

No.(%)

Total (N=406)

No(%)

Overweight

5(1.2)

21(5.2)

26(6.4)

Obese

5(1.2)

2(0.9)

7(1.7)

2

c for Overweight = 9.54, df =1, P=0.002

2

c for total overweight and obese 9.85,df =1,P =0.002

Table 4: Prevalence of overweight and obesity in the different

social classes.

Table 2: Mean BMI at various ages by sex

Age

(years)

Males Females

P-value

Social class

Overweight

No.(%)

Obese

No.(%)

No.

I

II

17(65.4)

1(3.60)

5(71.4)

-

2

3

4

5

6

2

20.9±0.00

18.75±3.16

14.00±1.04

14.89±1.91

15.96±1.92

4

17.20±0.44

16.16±2.76

16.16±2.57

15.76±2.83

14.95±1.45

0.000*

0.29

4

8

III

5(19.20)

1(14.3

6

7

0.07

13

29

16

22

0.35

IV

V

3(11.50)

-

1(14.3)

-

0.04*

7

8

36

29

15.73±1.13

15.65±1.49

18

23

14.77±0.93

15.19±0.71

0.00*

0.30

Total

26(100)

17(100)

9

1

18

29

8

16.10±1.44

16.38±1.39

14.89±0.98

15.78±1.44

15.05±1.88

27

29

12

13

9

16.72±2.53

16.61±1.57

16.45±1.24

19.16±2.83

18.01±3.58

0.35

0.55

0.03

0.04*

0.10

0

1

2

3

4

Discussion

11

1

4

5

2

6

18.00±0.28

22.55±0.12

14

7

18.56±2.14

20.06±2.25

0.72

0.02*

The present cross-sectional study established the body

mass index of predominantly urban children and adoles-

cent boys and girls from all social classes in the 2-

*

Statistically Significant

1

5 years age group. The body mass index was found to

In various ages, there was a statistically significant dif-

ference in the mean body mass index with the males

having a higher body mass index at ages 2,6,7 and 15

years while the females had a higher body mass index

of age 12 years. The mean body mass index increased

increase with age. After an initial decrease between 3

and 4 years, it remained relatively stable from 5- 8 years

and then increased with age beginning from 9 years. The

older subjects had the highest body mass index values.

The rapid rate of increase in body mass index corre-

sponds to the adolescent spurt growth which was

has been reported to occur in the 11-13 years age

2

from 16.33kg/m at two years to 17.43kg/m at₂ three

years. It subsequently decreased to 15.13kg/m at 4

2

14

years and remained stable at 15kg/m until 9years when

interval .

The mean values of body mass index in this present

2

it increased to 16.4kg/m and 20.86kg/m at 15 years.

The older age groups had the highest body mass index

values.

2

study (16.28 + 2.52kg/m )₆ are similar to the values

1

2

documented by Ansa et al (16.10 +2.10kg/m ). They

1

7

are lower than values from another study (18.25kg/

m ). These could be due to differences in body stat-

2

Prevalence of overweight and obesity

ure in the different populations and the different age

groups studied. Gender differences and other factors

such as ethnicity and genetics affect anthropometric

Using Cole et al’s international cut off points , the

prevalence of overweight was 6.4% (twenty six chil-

dren consisting of five males and twenty one fe-

males) and 1.7% of the subjects were obese. (Seven

children consisting of five males and two females)

1

8

data in childhood populations .

Females had a higher mean body mass index and simi-

lar findings have been re₁p₉_,o₂₀r_,t₂e₁d in Nigerian children in

other parts of the country

The prevalence of overweight and obesity in the subjects

by gender is presented in table 3 while the prevalence of

1

97

Using international cut off points proposed by Cole et al

in children should not be delayed until adulthood when

the pathophysiological changes associated with over-

weight and obesity are more likely to be established.

The best approach is prevention which should be

targeted at pre school and school children including

physical activity (cardiovascular fitness), nutritional

education (teaching children critical aspect of quality

nutrition, to reduce intake of high caloric low nutrition

foods) and behavior modification (change eating habits

and increase habitual physical activity). These preven-

tive₈measures have previously been found to be effec-

tive .

9

,

this study documented a prevalence rate of 6.4% and

1

.7% for overweight and obesity respectively. This

prevalence of obesity is much lower than the₂prevalence

2

of obesity among United States of America and Saudi

2

3

16,21

Arabia . Previous studies in Nigeria did not distin-

guish between overweight and obesity and different cut

off points for obesity were used. These could have

caused the differences observed in the prevalence of

obesity documented.

Socioeconomic status is also important. A difference in

standard of living is stated as one of the factors that

caused differences in body mass index among different

2

4

populations . In this study 65.4% of overweight and

Conflict of interest: None

Funding: None

7

1.4% of obese children were of the highest socio eco-

nomic class. Since parents of children from higher socio

economic groups also have better incomes, higher edu-

cational levels and therefore access to western life-

styles , it is presumed that this could affect the diet and

paediatric care that that these children received in their

infancy and early childhood and thus they have higher

body mass index values. With improvement in socio-

economic conditions, obesity may become a public

health problem in Nigeria. Management of overweight

Acknowledgement

The Authors are grateful to staff and students of par-

ticipating schools in Enugu, Nigeria for their coopera-

tion . We also thank Ms Nkeiru Madu for secretarial

assistance.

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