Body Fat and Energy Requirements ofPreparatory School-aged Children in the Gaza strip.
Running title: Zabut et al: Body Fat and Energy Requirements ….
Key words: body mass index, percent body fat, energy requirements, the Gaza strip, preparatory school-aged children.
Baker M. Zabut*, Associated Prof. in Biochemistry and Nutrition, Head of
Chemistry/Biochemistry Dept, Faculty of Science, IUG.
Osama S. Abu-Nada, M. Sc. Student, Clinical Nutrition Prog., Al-AzharUniversity,
Basil J. Kanao, M. Sc. Biology, M. Sc. Student, Clinical Nutrition Prog., Al-Azhar University,
*Corresponding Author:
Abstract
Background:Anthropometric measures are frequently used for assessment of nutritional status. They include weight, height, body mass index (BMI), etc. BMI provides a reliable indicator of body fatness for most people and is used to screen body composition in clinical and epidemiological studies.
Basal metabolic rate (BMR) isan energy expenditure of the body at completely rest in the post absorptive state. On the other hand, physical activity level (PAL) is an energy expended in physical activity of the body. Total daily energy requirements (TDR) is primarily composed of two different components which areBMR and PAL.
Aim:This study was conducted to describeanthropometric measures of the body fat and energy requirementsof preparatory school-aged children (PSC)in three different sociodemographical and economicalareas in the Gaza Strip
Subjects and methods:Study sample wascross sectional and random that obtained fromNorthern, Middle (Gaza city), and Southern Governates of the Gaza strip. It was selected from two preparatory schools(one for males and the other for females) per each area. It consisted of 680 PSC (350 males and 330 females) aged 12 to 14 yrs. Age, weight, and heightwere recorded for each pupil in the sample.Logistic data were analyzed by SPSS WIN program.
Results:Results of the study showedstatistical significant differencesinPBF and energy requirements between both sexesin the three different Governates(p0.01). In contrast to the other regions, a significant difference was not observed in BMI between the male and the female pupilsin the Gaza city(p= 0.62). The results also showed that BMI is highly correlated withPBF or energy requirements (p<0.01) for the males or the females in the three regions. However, means of BMIand PBF for the total study male pupils were 19.07 (3.42), 17.47 (5.07) kg/m2, and for the total female pupils were 19.85 (3.67), 22.25 (5.47) kg/m2, respectively. On the other hand, means of BMR and TDR for the total male pupils were 1461 (197), 2484 (336) kcal/day and for the total female pupils were 1309 (115), 2226 (196) kcal/day, respectively. The resultant BMI and BMR values werefound similar to those reference values for the same age and sex that have been reported before. Moreover, It was also observed that there were strong statistical significant relationships (P<0.01) between BMI and with either PBF or BMR among the total males and among the total females.
The results of the study also showed that there were significant differences in BMI, PBF, and energy requirements between the males in the Gaza city and the Southern Governate. These differences of same anthropometric measures forthe male pupils in the Northern Governate were not observed with the other regions. In contrast, there were no significant differences in theses variables for the female pupilsin the three localities.
Conclusion:BMI can be considered a reliable indicatorof body fatness as well as energy metabolism among PSC in the Gaza strip. Moreover, some statistical significant variations in the anthropometric measures were observed among the male pupils inthe Gaza city and the Southern Governate.
Key words: body mass index, percent body fat, energy requirements, the Gaza strip, preparatory school-aged children.
Introduction
Adolescenceis a significant period of human growth and maturation. It begins with puberty and includes those of 10-19 years old. It is characterizedby low prevalence of most infection and chronic diseases, but high health risks associated with sexual transmitted disease, drug abuse, pregnancy accidental and intentional injuries in the developed countries [Williams and Anderson 1993]. According to the World Health Organization [WHO 1995], adolescents comprise about 19% of the world’s population (approximately 1.2 billion people), yet “adolescents remain a largely neglected, difficult-to-measure, and hard-to-reach population, in which the needs of adolescent girls in particular are often ignored”.
Nutrition assessment evaluates a person's health from a nutrition perspective. Many assessment techniques have been developed to detect sign(s) of malnutrition which are dietary data, anthropometric measures, physical examination and biochemical analysis. Anthropometric measures include weight, height, BMI, etc. BMIprovides a reliable indicator of body fatness for most people and is used to screen body composition in clinicalandepidemiological studies[Garrow and Webester 1985; Watkins et al. 1992; Wellens et al. 1996; Zabut 2005].However, differences in BMI between people of the same age and sex are usually due to body fat. The exceptions to this rule are body builders, pregnant woman, and people with physical disability who are unable to walk, and people with either anorexia nervosa or massive obesity [Nakanishi et al. 2000].
PBF in healthy subjects can be estimated by using numerous techniques such as total body electrical conduction, Bioelectrical impedance analysis, dual energy X-ray absorptiometry etc [Ellis 1996]. These methods are sophisticated and require well equipped research facilities to apply to large number of subjects, especially in developing countries. For routine clinically and epidemiological use, simple and readily available anthropometric measurements such as BMI are preferable variable for predicting body composition including PBF[Garrow and Webester 1985; Zabut 2005].Nevertheless, many formulas, nowadays, are available to predict PBF, based on current BMI, age, and gender [Jakson et al. 2002]. The prediction error of using BMI in estimation of PBF is comparable to prediction error obtained with other methods estimating PBF[Deurenberg et al, 1991; Rounbenoff et al. 1995,].The relation between fatness and BMI differs with age and gender. For example, women are more likely to have higher percent of body fat than men for the same BMI.It should be emphasized thatdegree of fatness, reflects the number and the size of fat cells-adipocytes-maturing up the adipose tissue. Body fat may account 15-30% of total body weight among males and 20-35% among females. It differs according to age, gender, and exercise[Williams and Anderson 1993].
BMR is defined as the rate of energy expenditure at completely rest in the post absorptive state after 12 hours overnight fast. It represents the energy needed to sustain the metabolic activity, plus the energy to maintain blood circulation and respiration inthe awake state. BMR compromises 60%-70% of TDR upon sedentary activity. It can be measured by indirect calorimetrical method or can be predicted on the basis of age, body area or body weight and body height [Cataldo et al, 1989; Whitney et al. 1990; Al-Mokhalalaty 1997].
The thermic effect of feeding (TEF) refers to energy expenditure associated with digestion, absorption, and increased sympathetic nervous system activity after eating a meal. This component accounts for approximately 5%-10% of TDR. Thus, for the purpose of rough estimation, TEF can be ignored because its value is less than errors in estimation of energy requirements [Segal 1985]. Thus, TDR is roughly composed of two different components which are BMR and PAL[Cataldo et al, 1989; Whitney et al. 1990]. PAL is a result of voluntarily mechanical work, such as exercise, daily activities, and non-voluntarily activity, such as, spontaneous muscle contractions, and maintaining posture; this accounts for 15%-50% of TDR or even more [Cataldo et al, 1989; Whitney et al. 1990; Al-Mokhalalaty 1997]. Nevertheless, amount of BAL depends on intensity and duration of activities, and body weight. Thus, it is considered as the most variable component of the body energy expenditure.
There was one study aboutnutritional status and life style among school adolescents aged 12-15 yrs in the Gaza strip [Abudayya 2003]. Thestudy analyzed public health problems such as obesity, stunting and anemia among 942 adolescents attending 10 preparatory schools in the Gaza city and the Northern Governate.
Significance and objectives of the study:The Gaza strip is an over populate area, a bout 1.5 million live in 365 km² where the poverty level in this locality reached more than 70%last year [Palestinian Central Bureau of statistics report 2007].It undergoes from socio-cultural, demographic environmental and political risk factors that continuously characterize the Palestinian population. These factors are often considered as determinantsof nutritional status in undeveloped countries. Although numerous studies have been reported about malnutrition among children and pregnant women[Palestinian Ministry of Health2005] as well as some studies about adults in the Gaza Strip and the west Bank [Abdul-Rahim et al. 2003; Zabut 2005], nutritional assessment of Palestinian adolescents as a group have been largely ignored. They are not only ignored by heath care providers but also by heath policy makers in spite of they represent about 25% of thePalestinian population [Palestinian Ministry of Health, 2005]. Therefore, this study aimedto assess body fat and energy metabolism of PSC through determination of BMI, PBF andBMR, TDR. It also aimed to test whether there is a correlation between BMI and PBF or energy requirements of these pupils.
Methods
Study design:Cross sectional study was applied among PSC in the Gaza strip.
The study population:The target population of the study was PSC aged 12to14 years old. The total numberof thispopulation in the Gaza strip was 121,937 pupils [Report of Ministry of Education and Higher Education, 2007].
Study area:This study was carried outin three different areas of the Gaza Strip. These areas areGaza city in the middle, SouthernGovernate and Northern Governatein theGazastrip.
Ethical consideration:A consent form was obtained from Ministry of Education (MOE)offices in each Governate.
Sampling and tools of the study:Two largest prep. schools were chosen in each area of the study one for males and the other for females. In each school, the numbers of pupils were selectedrandomly from the three classes according to the total number of PSC in each area. The age range of these pupils was 12-14 yrs, assuming similarities in living conditions in order to decrease confounding variables. The importance and nature of this study were explained to the manager of each school who participated in collecting randomly the required number of pupilsduring a brake time. Most of pupils collected were agreed freely to participate in this study and registered in. Thenage, height and weight of thepupilswere recorded. The samestandiometer and an electronic weighing scale were used for measuring the weight and the height of the pupils to nearest of 0.1 kg and 0.5 cm,respectively.The total cross sectional sample of pupils was700 pupils who their response rate was 97%of PSC(350 males and 330 females).
Operational definitions:1. BMR based on weight (Wt) and height (Ht) for the pupils were calculated according to Schofield's equations (BMR for the male pupils = 16.2 xWt + 137 xHt + 516 and BMR for the female pupils = 8.4 x Wt + 466 xHt + 200) [Schofield et al. 1985].
2.PAL of the PSC was calculated roughly by multiplying BMR by 1.70 factor [Schofield et al. 1985; Al-Mokhalalaty 1997].
3.TDR ≈ BMR + PAL [Cataldo et al, 1989; Whitney et al. 1990].
4.BMI = Wtin Kg/ Ht in squared meter.
5.Predicted PBF of the pupilswas calculated from BMI, age and gender according to the Deurenberget al.[1991] equation of adolescents (PBF = (1.51 BMI) – (0.70 Age) – (3.6 gender) + 1.4where male gender = 1,andfemale = 0.
Data Collection:Estimated BMR, approximated TDR, measured BMI, and predictedPBF were calculated according to the above operational definitions for every pupil in the study sample and filled in his/her specific record.
Data analysis:From the PSC anthropometric measures, energy requirements (Kcal/day), BMI, and PBF were calculated using SPSS WIN (Version 13).
Student t-test and ANOVA test were carried out at a significance level of 5 %, for two and more than two numerical means, respectively. Any difference between variables was considered statistically significant if p value less than 5 %.
Pearson's correlation coefficient (r) was done at a significant level of 1 %, and any correlation between two ratio scale data was considered statistically significant if p value less than 1 %.
Data assessment: Data were assessed by comparing results of the Gaza strip Governates with each other and bycomparing results of the total sample of PSC with standard reference values of the same age [FAO/WHO/UNU 1985; WHO 2007].
Results
Table I: Mean (SD) BMI, PBF, BMR and TDR among PSC in GC.
Variable / Males (n=116) / Females (n=110) / P valueBMI(kg/m2) / 19.77 (3.62) / 19.51 (4.00) / 0.62
PBF / 18.53 (5.40) / 21.75 (5.97) / 0.00
BMR(Kcal/day) / 1494 (210) / 1306 (121) / 0.00
TDR(Kcal/day) / 2540 (357) / 2220 (206) / 0.00
r (BMI & PBF) among the males or among the females = 0.99 (p< 0.01).
r (BMI & BMR) among the males = 0.87 (p< 0.01) and amongthe females = 0.89(p<0.01).
Table Ishows mean and SD values of BMI, PBF and energy requirements in the Gaza city. BMI values for males and females were 19.77(3.62) and 19.51(4.00) kg/m2 whereas PBF values were 18.53(5.40) and 21.75(5.97) Kg/m2, respectively. Moreover, BMR and TDR were 1494(210), 2540(357) and 1306(121), 2220(206) Kcal/day for males and females respectively.However, these results showed significant differencesin PBF and energy requirement between both sexes(p0.01). In contrast, no significant difference was observed in BMI between them in the same region of the Gaza strip(p= 0.62). The results also showed that BMI was highly correlated with PBF or energy requirements for the male pupils (r=0.87, p<0.01) or the females(r=0.89, p<0.01). Similar results were also obtained for PSC in Northern (table II) and Southern (table III) Governates. In contrast to the Gaza city, BMI among males and females was statistically significant in these regions (p<0.05)
Table II: Mean (SD) BMI, PBF, BMR and TDR of PSC in JRC.
Variable / Males (n=123) / Female (n=116) / P valueBMI(kg/m2) / 18.92 (3.12) / 19.95 (4.00) / 0.03
PBF / 17.26 (4.64) / 22.42 (6.01) / 0.00
BMR(Kcal/day) / 1465 (185) / 1312 (126) / 0.00
TDR(Kcal/day) / 2491 (315) / 2231 (215) / 0.00
r (BMI & PBF) amongthe males or among the females = 0.99 (p< 0.01).
r (BMI & BMR) amongthe males = 0.87 (p< 0.01) and among the females = 0.91(p<0.01).
Table II shows that BMI (SD) values for PSC were 18.92(3.12) and 19.95(4.00),whereasPBF means were 17.26(4.64) and 22.42(6.01) Kg/m2 for the males and the females, respectively. It also shows that BMR and TDR were 1465(185) and 2491(315), whereas they were1312(126) and 2231(215) Kcal/day for the males and the females in the same region, respectively.
Table III: Mean (SD) BMI, PBF, BMR and TDR among PSC in GV.
Variable / Males (n=111) / Female (n=104) / P valueBMI(kg/m2) / 18.51 (3.41) / 20.10 (2.81) / 0.00
PBF / 16.59 (5.04) / 22.59 (4.14) / 0.00
BMR(Kcal/day) / 1421 (192) / 1308(94) / 0.00
TDR(Kcal/day) / 2415 (326) / 2225 (160) / 0.00
r (BMI & PBF) amongthe males or among the females = 0.99(p<0.01).
r (BMI & BMR) amongthe males = 0.89 (p< 0.01) and among the females = 0.90 (p< 0.01).
In the Southern Governate, table III shows that BMI values were 18.51(3.41) and 20.10(2.81) whereas PBF were 16.59(5.04) and 22.59(4.14) Kg/m2 for the males and the females,respectively. In addition BMR and TDR values were 1421 (192), 2415(326) and 1308 (94),2225(160) Kcal/day for males and females, respectively. Tables II and III also show that BMI was strongly correlated with either PBF (p<0.01) or BMR (p<0.01) among the males or among the females of PSC in the Northern and the SouthernGovernates.
Table IV: Mean (SD) BMI, PBF, BMR and TDR amongPSC in the Gaza Strip.
Variable / Males (n=350) / Female (n=330) / PvalueBMI(kg/m2) / 19.07 (3.42) / 19.85 (3.67) / <0.01
PBF / 17.47 (5.07) / 22.25 (5.47) / 0.00
BMR(Kcal/day) / 1461 (197) / 1309 (115) / 0.00
TDR(Kcal/day) / 2484 (336) / 2226 (196) / 0.00
r (BMI & PBF) amongthe males or among the females = 0.99 (P<0.01).
r (BMI & BMR) amongthe males = 0.87 (p<0.01) and among the females = 0.88(p<0.01).
Table IV shows the mean and SD values of BMIand PBF for the total study male pupils were 19.07 (3.42), and 17.47 (5.07) Kg/m2 whereasfor the total female pupils were 19.85 (3.67) and 22.25 (5.47)Kg/m2, respectively. On the other hand, BMR and TDR values for the total study male pupils were 1461 (197) and 2484 (336) kcal/day and for the total study female pupils were 1309 (115) and 2226 (196) kcal/day, respectively. Correlation coefficient between BMI with either PBF or
BMR was also tested for the total study PSC. There were strong statistical significant relationships (P<0.01) between these variables among the total males and among the total females.Comparing the BMI values of the total PSC withvery recent reference Z-score values of WHO of the same age and sex [WHO 2007], it was found that these values lie within the corresponding optimal rang (18.2-20.8 kg/m2in average). On the other hand,BMR values of the study PSC were also compared with those reference BMR values reported by WHO and other organizations [FAO/WHO/UNU 1985] which were 1418 and1310 Kcal/dayfor adolescents boys and girls, respectively. It was found that the BMR for the males are slightly greater than the corresponding reference value, whereas the BMR for the females are identical to the reference value.
Table V: Mean (SD) BMI, PBF, BMR and TDR among themale pupils in the Gaza strip
Variable / Gaza(n=116) / South
(n=111) / North
(n= 123) / P value
BMI(kg/m2) / 19.77a (3.62) / 18.51b (3.41) / 18.92ab (3.12) / S
PBF / 18.53a (5.40) / 16.59b (5.04) / 17.26ab (4.64) / S
BMR(Kcal/day) / 1494a (210) / 1421b (192) / 1465ab(185) / S
TDR(Kcal/day) / 2540a (357) / 2415b(326) / 2491ab(315) / S
Means of different superscripts differ significantly where S: significant (p<0.05).
Applying ANOVA test (table V) for measuring the differences between BMI, PBF, BMR and TDR in the three regions showed that there were significant differences between the males in Gaza city and Southern Governate. These differences forthe males in Northern Governate were not observed with the other regions.
Table VI: Mean (SD) BMI, PBF, BMR and TDR among the female pupils in the Gaza strip.
Variable / GC(n=110) / GV
(n=104) / JRC
(n= 116) / P value
BMI(kg/m2) / 19.51 (4.00) / 20.10 (2.81) / 19.95 (4.00) / NS
PBF / 21.75 (5.97) / 22.58 (4.14) / 22.42 (6.01) / NS
BMR(Kcal/day) / 1306 (121) / 1308(94) / 1312 (126) / NS
TDR(Kcal/day) / 2220 (206) / 2225 (160) / 2331 (215) / NS
NS: Not significant (p>0.05).