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Extended Essay

The study of obesity among primary school pupils in Szkola

Europejska

Research Question: Does calorific content, amount of proteins, carbohydrates and fats in

the school meals contribute to the abnormalities in body mass index among 9-12 aged

pupils of Szkola Europejska in Lodz?

IB Subject: Biology

by ……………………………

Candidate: ……………………

School: Szkoła Europejska (003065)

Łódź, Łódzkie, Poland

Diploma Session: May 2013

Word Count: 3936

Acknowledgments

I would like to thank my supervisor Mrs Marta Kamasińska for her continuous support,

guidance and providing me with valuable insight into this work. I would like to thank the

school nurse for letting me use her medical equipment in this research.

1

ABSTRACT:

The experiment was conducted to study the obesity among primary school pupils in

Szkola Europejska. The research question was formulated as: Do calorific content,

amount of proteins, carbohydrates and fats in the school meals contribute to the

abnormalities in body mass index among 9-12 aged pupils of Szkola Europejska in

Lodz?

The data was collected by measuring height and weight among 9-12 years old children

and giving them a questionnaire to fill. Also school meals menus throughout a week

were collected.

The data collected for height and weight was calculated into BMI values and then

subjected to two-tailed t-test. Subsequently, calorific content of school meals and their

amount of proteins, carbohydrates and fats were calculated and their relation to the

daily demand was determined. Those results were then compared to the number of

hours children spent on sports. Afterwards, the time required to burn average energy

value of a school meal was calculated.

The calculations of BMI value among 9-12 aged children showed that average BMI varies

between 5th percentile and 85th percentile, which is categorized as healthy weight. The

comparison of the t-test values proved no significant difference between children’s BMI

on average. Furthermore, it was showed that the daily breakfast demand for calories is

met only in 48%, and in the case of lunches is met in 89%. While the average content of

carbohydrates and fats in school meals is normal, the average protein content in school

meals exceeds 10% of the daily demand. Moreover, the calories burned during normal

activity exceed the average number of calories consumed in school meals.

The results indicated that school meals do not contribute to the BMI abnormalities

among 9-12 aged children and they do not exceed the daily demand for calories.

Nonetheless, the tendency to consume low-calories breakfasts and high-calories lunches

was manifested.

Word count: 302

2

CHAPTER 1: INTRODUCTION……..………………………………..................................................6

1.1 Research question……..………………………………..................................................……………6

1.2 Genesis of the work..………..………..………..………..………..………..………..………..………..…6

1.3 Theoretical background………..………..………..…………..………..………..…………..…………7

CHAPTER 2: METHODOLOGY………..………..………..…………..………..………..…………..….11

2.1 Objectives of the study………..………..………..…………..………..………..…………..…………11

2.2 Hypothesis………..………..………..…………..………..………..…………..………..………..………..11

2.3 Variables………..………..………..…………..………..………..…………..………..………..…………..11

2.4 Materials………..………..………..…………..………..………..…………..………..………..…………..12

2.5 Procedures………..………..………..…………..………..………..…………..………..………..………..12

2.6 Statistical analysis………..………..………..…………..………..………..…………..………..………13

CHAPTER 3: DATA COLLECTION AND PROCESSING………..………..………..…………14

3.1 Raw data for children………..………..………..…………..………..………..…………..………..…14

3.2 Raw data for school meals………..………..………..…………..………..………..…………..……15

3.3 Raw data for practiced sports………..………..………..…………..………..………..…………..18

CHAPTER 4: ANALYSIS AND INTERPRETATION:………..………..………..…………..…...19

4.1 BMI calculations:………..………..………..…………..………..………..…………..………..…………19

4.2 Food calculations:………..………..………..…………..………..………..…………..………..………..24

4.3 Sport calculations:………..………..………..…………..………..………..…………..………..……….27

CHAPTER 5: CONCLUSION AND EVALUATION………..………..………..…………..………29

5.1 Hypothesis I………..………..………..…………..………..………..…………..………..………..………29

5.2 Hypothesis II………..………..………..…………..………..………..…………..………..………..……..29

5.3 Caloric content of school meals ………..………..………..…………..………………..…………30

5.4 BMI………..………..………..…………..………..………..…………..………..………..…………..……….30

5.5 Sport………..………..………..…………..………..………..…………..………..………..…………..……..30

5.6 Evaluation………..………..………..…………..………..………..…………..………..………..…………32

3

BIBLIOGRAPHY………..………..………..…………..………..………..…………..………..………..………33

Appendix 1………..………..………..…………..………..………..…………..………..………..……………..34

Appendix 2………..………..………..…………..………..………..…………..………..………..……………..35

Appendix 3………..………..………..…………..………..………..…………..………..………..……………..36

CHAPTER 1: INTRODUCTION

1.1 Research question:

Does calorific content, amount of proteins, carbohydrates and fats in the

school meals contribute to the abnormalities in body mass index among 9-12

aged pupils of Szkola Europejska in Lodz?

1.2 Genesis of the work:

According to recent research, the number of overweight children in Poland has

increased three times over the past 20 years. It was estimated that the scale of the

obesity problem in Polish schools is coming closer to the one in America. While in

the United States, the percentage of children suffering from obesity is over 20%, in

Poland the issue applies to 18% children1. Furthermore, the consequences of

obesity among Polish children slowly begin to emerge: the majority of them suffer

from respiratory distress, hypoxia, hypertension, high cholesterol and dysfunction

of glucose metabolism. They eat too much salt, saturated fats and sugar, and not

enough fibre and unsaturated fats2. Under the influence of these studies, I began to

contemplate what is the determining factor of obesity among children. When

I started to look for the reasons behind this problem, I came across a large amount

of articles3 that suggested that one of the factors causing obesity among children is

the food served in schools. I was intrigued whether in my school, the school meals

contribute to weight problems among children of the primary school. Therefore,

a thorough study of the relationship between the consumption of meals at school

and the tendency to be overweight should be done.

1 http://zdrowie.dziennik.pl/profilaktyka/artykuly/408809,trzykrotnie-wzrosla-liczba-otylych-dzieci-w-polsce-warszawa-chce-walczyc-z-nadwaga-i-otyloscia-w-szkolach.html2 http://www.farmacjaija.pl/zdrowie/co-powinny-jesc-dzieci.html3 http://children.webmd.com/news/20100315/school-lunches-linked-to-kids-obesity

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1.3 Theoretical background:

Body Mass Index

Body Mass Index (BMI) or Quetelet index, is an estimate of body composition used

extensively as an indicator of whether an individual is clinically classified as obese.

The Body Mass Index is defined as weight in kilograms divided by the square of

their height in metres4.

BMI= mass[kg](height [m ])2

Estimating the BMI for children slightly differs from the one for adults, given that a

child’s BMI changes while they mature. In children, the child’s age is necessary in

order to compare the obtained result to typical values for children of the same age.

Instead of fixed thresholds for underweight and overweight such as those used for

adults, the BMI percentile indicates the relative position of …………., etc

Importance of breakfast and lunch consumption

Eating breakfast is the most optimal way to meet the energy needs of the body. Daily

consumption of breakfasts provides a better functioning of the digestive and circulatory

system and improves the ability to concentrate. If an individual does not provide the

body with food in a breakfast, in their empty stomachs hypersecretion of acid occurs,

therefore causing mucous membrane irritation and disruption of the digestive system.

Resistance to cold decreases and the concentration of glucose in the blood decreases,

which can lead to dizziness or even fainting. For this reason, some people may prove

themselves to be less efficient at work or school. The research that was carried out on a

group of several hundreds of British has confirmed that regular breakfast consumption

improves mood and well-being5. Two experimental groups were set up, both of which

ate according to their previously calculated energy requirements. The only difference

between the two groups lied in the fact that one group ate their entire portion of calories

in the morning (provided in a large breakfast), and the other group, for dinner. The

4 Michael Kent, Oxford Dictionary of Sports Science & Medicine Second Edition, page 745 http://www.masaz.toskar.info/sniadanie-najwazniejszym-posilkiem-dnia.php

5

group that ate in the evening gained weight, whereas the other group that ate in the

morning lost weight, even though they all ate as much as their body theoretically

needed. Therefore, in order to maintain a constant weight, the amount of food consumed

is as essential as the way it affects the metabolism. The sooner the body is provided with

food, the more the body is set to burn the energy supplied to it, however, the later there

is a greater tendency of body fat deposition. Daily breakfast consumption increases the

metabolism from 3 to 10%, consequently, we can gain or lose 10 pounds on an annual

basis6.

The benefits of regular breakfast consumption:

Better resistance to stress

Immune system is more efficient

Nervous system is more efficient

Helps in maintaining healthy weight

Controls hunger throughout a day

Reduces the likelihood of overeating

In Poland, the tendency to eat low-calories breakfasts and high-calories lunches is

manifested. According to recent research conducted in Poland, 22% of parents claimed

that their children do not eat breakfast three out of five days a week. Only slightly more

than half of the parents make sure that their children do not come to school hungry.

Moreover, 95% of children between 6 and 11 years old, do not consume lunch at school,

and one in five Poles do not eat breakfast at all7.

Daily demand for calories and the role of essential nutrients in the human body

Calories

The recommended food ration is deliberately chosen set of products, including their

amount in order to cover the body’s daily requirement for all nutrients. The

recommended daily calories intake for children aged 9-12 years is 2300 cal. Depending

6 http://www.masaz.toskar.info/sniadanie-najwazniejszym-posilkiem-dnia.php7http://metromsn.gazeta.pl/Lifestyle/1,126513,12818816,Polacy_nie_jedza_sniadan__To_niezdrowo__Jak_ich_zachecic.html

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on the number of meals per day, breakfast should coincide 25-35% and lunches 15-30%

of total daily caloric intake8.

Proteins

Protein is the basic structure of all living cells. It is an important part of cell membranes,

blood (haemoglobin) and enzymes. Proteins determine the growth of young organisms

and support the growth of hair, nails and help in reconstruction of damaged skin

epithelium and healing of wounds. Antibodies are made up of proteins, therefore they

play protective role in the organism. The effects of protein deficiency include……., etc

Carbohydrates

Carbohydrates are the main source of energy to the body, providing approximately 50-

60% of the energy. Deficiency of carbohydrates in a diet is harmful to the body and

reveals itself primarily as a feeling of hunger, general weakness, fainting, muscle tremor

and convulsions. The symptoms of hypoglycemia are related to the shortage of sugar as

the basic energy material for muscles and nerve cells. At least one third of daily calories

should come from energy supplied by carbohydrates. It is estimated that ………, etc

Fats

Fats play important role in the human body. They provide a significant amount of energy

(20 to 35%). One gram of fat gives the body 37.7 kJ of energy; approximately twice as

much as proteins and saccharides. Fats are also a major source of essential fatty acids

and fat-soluble vitamins (A, D, E and K). Some fatty acids are involved in the synthesis of

certain hormones tissues, such as prostaglandin. Fats in moderate amounts are the

essential human nutrients. They are the main source of ………………, etc

CHAPTER 2: METHODOLOGY

2.1 Objectives of the study:

To calculate the caloric content of school meals.

To estimate the average number of hours spent by children on sport activities.

8 Wiesław Graban, Witold S. Gomułka, Encyklopedia Zdrowia, Wydawnictwo Naukowe PWN, Warszawa 2001, page 383

7

To verify how much exercise is needed to burn the average school meal

To check whether school meals are appropriate for pupils of particular age.

2.2 Hypothesis:

HYPOTHESIS 1 : School meals exceed the daily breakfast and lunch demand for

calories and daily demand for proteins, carbohydrates and fats.

HYPOTHESIS 2 : School meals have too many calories to be burnt during the

pupil’s normal activity.

2.3 Variables:

Table 2.1 – Independent, dependent and controlled variables in the experiment

Independent Variables Dependent Variables Controlled Variables

Subjects

School meals

The number of hours

spent on sports by

children

Weight [kg]

Height [m]

Age

Gender

Body mass index

(BMI)

The amount of

proteins,

carbohydrates and

fats in school meals

[g]

Caloric content of

school meals [kcal]

Age group (children

between 9 and 12

years old)

Length of the

experiment (5 days)

2.4 Materials:

Stadiometer

Medical Scale

CDC Body Mass Index-For-Age Percentiles for boys (2 to 20 years) (Appendix 1)

CDC Body Mass Index-For-Age Percentiles for girls (2 to 20 years) (Appendix 2)

8

Texas Instruments TI-84 Plus

Food calorie table

Questionnaire (Appendix 3)

Letter to parents asking for permission to conduct research on their children

(Appendix 4)

2.5 Procedures:

Procedure 1 – Medical examination of the children

1. Before the experiment begins, ask the parents for permission to conduct the

research on their children.

2. Having a parental consent, collect a group of children between the ages of 9 to 12

years (five or more in each age group).

3. Measure the height and weight of each child using stadiometer and medical scale.

4. Give them previously prepared questionnaire about sports they practice.

5. Having collected all the data, calculate each child’s BMI and plot it on CDC Body

Mass Index-For-Age Percentiles growth chart for either boys or girls, in order to

find out the percentile range and weight status category of a particular child.

6. Calculate the amount of …………………., etc

Procedure 2 – School meals

1. Everyday for one week, collect the school meals menu of food that children

consume.

2. Once all the data is collected calculate the caloric content of school meals using

food calorie table.

3. Calculate how much protein, fats and carbohydrates those meals contain.

4. Compare the obtained results with daily food intake for various calorie demands.

5. Evaluate the results.

2.6 Statistical analysis

Mean:

x= ΣxN

Standard deviation:

9

σ=√∑ (x−x)2

N

T-test:

t=(xmean1−xmean2)

√ S12n1 +S22

n2

CHAPTER 3: DATA COLLECTION AND PROCESSING

…………………………………………………………………………..……..

………………………………………………………………………………….

CHAPTER 4 – ANALYSIS AND INTERPRETATION4.1 BMI calculations

As it can be seen in tables 4.1-4.4, information about BMI of children aged 9-12

years old, is presented. BMI was calculated using the following formula:

BMI= mass[kg](height [m ])2

. The obtained values were then marked on the CDC Body Mass

Index-For-Age Percentiles growth charts in order to receive a percentile ranking

and weight status category of children.

Table 4.1 – BMI, percentile range and weight status category for 9 years old children

9 year old children

BMI Percentile rangeWeight status

category

1 17 5th percentile up to the 85th percentile Healthy weight2 20 85th to less than the 95th percentile At risk of overweight3 14 5th percentile up to the 85th percentile Healthy weight4 15 5th percentile up to the 85th percentile Healthy weight5 15 5th percentile up to the 85th percentile Healthy weight

Average 16 5th percentile up to the 85th percentile Healthy weightSD 2.17

10


10 year old children


category

1 15 5th percentile up to the 85th percentile Healthy weight2 20 85th to less than the 95th percentile At risk of overweight3 20 85th to less than the 95th percentile At risk of overweight4 16 5th percentile up to the 85th percentile Healthy weight5 17 5th percentile up to the 85th percentile Healthy weight6 17 5th percentile up to the 85th percentile Healthy weight



11 year old children BMI

Percentile rangeWeight status

category

1 26 Greater than or equal to the 95th percentile Overweight2 20 5th percentile up to the 85th percentile Healthy weight3 17 5th percentile up to the 85th percentile Healthy weight4 15 5th percentile up to the 85th percentile Healthy weight5 15 5th percentile up to the 85th percentile Healthy weight6 17 5th percentile up to the 85th percentile Healthy weight





category

1 18 5th percentile up to the 85th percentile Healthy weight2 19 5th percentile up to the 85th percentile Healthy weight3 18 5th percentile up to the 85th percentile Healthy weight4 20 5th percentile up to the 85th percentile Healthy weight5 21 85th to less than the 95th percentile At risk of overweight6 18 5th percentile up to the 85th percentile Healthy weight7 20 5th percentile up to the 85th percentile Healthy weight


In order to establish if the difference between children’s BMI is significant, a two-tailed

Student’s t-test is performed. Based on BMI values of 9 and 10 years old children, a test

of comparing the mean and standard deviation of two sets of samples to see whether

11

they are equivalent or different, is conducted. A value for t is calculated using

a statistical formula:

t=(xmean1−xmean2)

√ S12n1 +S22

n2

The result of t-test for BMI values of 9 and 10 years old children came out as follows:

Table 5 – Example calculations for the t-test

Body Mass Indexx x−x (x−x )2

9 year old children


9 year old children


9 year old children


17 15 1 -3 1 920 20 4 2 16 414 20 -2 2 4 415 16 -1 -2 1 415 17 -1 -1 1 1- 17 -1 - 1

n9=5 n10=6 ∑(x−x)2 23 23

Figure 2 – Example calculations for the t-test

1. State the null and alternative hypothesis

H 0=μBMI of 9 years old children=μBMI of 10 years oldchildren

H A=μBMI of 9 years oldchildren≠μBMI of 10 years old children

2. Calculate the variances

S9 years old2 =

Σ(x−x )9 years old2

n9−1

S10 years old2 =

Σ(x−x)10 years old2

n10−1

12

S9 years old2 = 23

5−1=5.75

S10 yearsold2 = 23

6−1=4.60

3. Calculate the actual difference between means

¿

4. Calculate the t value

t=(xB−xA)

√ S92n9 +S102

n10

= 1.15

√ 5.755 + 4.606

=0.83

5. Determine degrees of freedom

d.f. (n9+n10−2 )=(5+6−2 )=9

6. Consult the t-table

For the calculation of Body Mass Index, the calculated value of t=0.83 is lower than the

critical value=2.26, therefore there is no significant difference between BMI of 9 years

13

old children and 10 years old children on average and we do not reject

H 0=μBMI of 9 years old children=μBMI of 10 years oldchildren .

Graph 4.1 – Average Body Mass Index (BMI) for 9-12 years old children.

9 years old children 10 years old children 11 years old children 12 years old children0123456789

10111213141516171819202122

1618 18 19

Age group

Ave

rage

Bod

y M

ass

Ind

ex (

BM

I)

Average BMI value in children aged 9 years is 16, which is 5th percentile up to the 85th

percentile in percentile range and it is categorized as healthy weight. In the case of 10

and 11 year-olds, average BMI value is estimated to be 18, which is also classified as

healthy weight. In 12 year-old children, average BMI value is 19 and it is categorized as

healthy weight as well. Among the 24 children examined, subject 1 (11 years old) is the

only one whose BMI percentile is greater than or equal to the 95th percentile, which is

categorized as overweight in weight status category. In the case of subject 2 (9 years

old), subject 2 and 3 (10 years old) and subject 5 (12 years old) BMI percentile is 85th to

less than the 95th percentile in percentile range, which is classified as at risk of

overweight. Those children who deviate from the average represent 21% of all

examined children and a child, whose BMI is in the extreme value of 10% on the upper

side of the CDC BMI growth charts (above the 95th percentile) require careful

observation.

14

4.2Food calculationsAverage energy value of food, proteins, carbohydrates and fats obtained from both

breakfasts and lunches was calculated using the following formula: x=Σ xN

Table 4.5 – Average energy value of food, proteins, carbohydrates and fatsDay of the week Energy value of food

[cal] (±0.01)Proteins

[g] (±0.01)Carbohydrates [g]

(±0.01)Fats [g](±0.01)

Monday 949.50 48.09 110.08 33.77Tuesday 1075.48 57.67 83.06 59.34

Wednesday 1054.26 41.06 104.37 54.20Thursday 963.81 44.73 76.09 52.81

Friday 956.39 58.54 120.26 30.05Average 999.89 50.02 98.77 46.03

SD 53.67 6.97 16.63 11.79

Graph 4.2 – The daily demand for proteins, carbohydrates and fats.

Proteins Carbohydrates Fats0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

110%

120%

110%

34%

72%

Essential nutrients

Th

e p

erce

nt

dai

ly v

alu

e fo

r es

sen

tial

nu

trie

nts

(%

)

As it can be seen on the graph above, average protein content in school meals exceeds

10% of the daily demand for proteins. Daily requirement for carbohydrates is met in

34% and in the case of fats, the daily demand is met in 72%.

15

Graph 4.3 – The percent daily demand for calories

Monday Tuesday Wednesday Thursday Friday0

10

20

30

40

50

60

70

80

90

100

4147 46 42 42

Energy value of food [cal]

Th

e p

erce

nt

dai

ly c

alor

ic v

alu

e fo

r sc

hoo

l m

eals

(%

)

The graph 4.3 presents the percent daily demand for calories in comparison to the

percent caloric content of food served in school. The values are roughly approximate to

each other, ranging between 40 and 50%. On Monday, daily demand for calories is met

in 41%, which makes it the lowest value, whereas on Tuesday, it is met in 47%, which

makes it the highest value.

Graph 4.4 – The percent daily demand for breakfasts and lunches

Breakfasts Lunches0

20

40

60

80

100

120

140

160

67

134

Th

e p

erce

nt

dai

ly d

eman

d fo

r b

reak

fast

s an

d

lun

ches

(%

)

16

The graph 4.4 demonstrates the average percent daily demand for breakfasts and

lunches obtained from school meals. The daily breakfast demand for calories is met in

48% and the daily lunch demand for calories is met in 89%.

4.3Sport calculationsAs it can be seen in graphs 4.5 and 4.6 energy balance of the body is calculated. Energy

balance is the difference between the amount of energy delivered to the body in food in

the form of carbohydrates, fats and proteins, and the amount of energy expended by the

body in the form of work and heat, in the same period of time.

Graph 4.5 – Comparison of the average number of calories burned through physical activity with an average caloric content of meals.

Average

calo

ries b

urned

thro

ugh physic

al ac

tivity

Average

calo

ries c

onsum

ed in

a sc

hool mea

l994

996

998

1000

1002

1004

1006

1008

1010

1012

1014

1012

1000

Calo

ries

[ca

l]

As it can be seen on the graph 4.5 the average number of calories burned through a

physical activity exceeds the average number of calories consumed in school meals.

Therefore, energy balance is balanced because both sides are approximately equal.

17

Graph 4.6 – The time required to burn average energy value in a school meal.

Cycling (20 km/h)

Swimming

Brisk walking

0 100 200 300 400 500 600

140

210

550

Time in minutes

The graph above shows how much an individual has to spend on a particular sport in

order to burn average caloric content of a school meal (999.89 cal). To burn the calories

consumed in shortest time possible, a child has to spend 140 minutes cycling at the

speed of 20 km/h, whereas, brisk walking takes the longest time to burn the energy

value of food.

CHAPTER 5: CONCLUSION AND EVALUATION

5.1Hypothesis I

The hypothesis I states that school meals exceed the daily breakfast and lunch demand

for calories and the daily demand for proteins, carbohydrates and fats. The graphs and

the processed data demonstrate that the daily breakfast demand for calories is met only

in 48%, therefore children obtain only half of the calories needed for their bodies to

function properly. In the case of lunches, the daily demand for calories is met in 89%,

which is fairly close to meeting the daily requirement. Therefore, the statement that in

Poland there is a tendency to eat low-calories breakfasts also applies to children, who go

to Szkoła Europejska. However, as far as the daily demand for proteins, carbohydrates

and fats is concerned, presented data clearly show that average protein content in

school meals exceeds 10% of the daily demand. Once again it must be emphasized that it

18

is not known whether children exceed this limit even further consuming more proteins

at home. The excessive consumption of proteins is as harmful as its deficiency and it

results in metabolic disorders, such as acidosis and it also increases the risk of obesity.

Therefore, school ought to reduce the amount of proteins in the school meals and

increase the amount of carbohydrates intake, which as the data demonstrate, meets the

daily demand only in 34%. From a health point of view, reducing the consumption of

carbohydrates is incorrect and unhealthy. Carbohydrates are not only a source of energy

for neurons but also facilitate fat burning. As far as fats are concerned, the daily demand

is met in 72% and it seems to be in sufficient quantity. Therefore, the hypothesis that

school meals exceed the daily breakfast and lunch demand for calories and the daily

demand for proteins, carbohydrates and fats must be rejected for calories,

carbohydrates and fats, but accepted for proteins.

5.2Hypothesis II

The hypothesis II states that school meals have too many calories to be burnt during the

pupil’s normal activity. The graphs and the processed data demonstrate that calories

burned during the pupil’s normal activity exceed the average number of calories

consumed in school meals. Therefore, the hypothesis must be rejected. However, the

data are not entirely accurate given the fact that some of the children examined in a

particular week did not practice sport at all and children who practiced a large amount

of sport made up that average. If the data for each child was calculated separately,

whether the hypothesis is either accepted or rejected would be different for each child.

5.3 Caloric content of school meals

The graphs and the processed data demonstrate that the daily demand for calories is

met approximately in 41-47%, therefore children get only half of the calories they need

in order for their body to function properly. Nonetheless, the experiment involved only

the food consumed in the school cafeteria and did not include meals consumed outside

of school. Consequently, it is not know whether children generally exceed or fall within

the limit of the daily demand for calories, however, the school meals certainly do not

exceed this limit.

5.4 BMI

19

Considering children’s BMI value, the average BMI is in 5th percentile up to the 85th

percentile range for each age group, which is categorized as healthy weight.

Furthermore, the t-test showed that there is no significant difference between children’s

BMI values of each age group on average. Nonetheless, there are four subjects that

deviate from the average. However, it is unlikely that school meals have contributed to

the abnormalities in their Body Mass Index. As I have mentioned before, it is not known

what children consume outside the school and what time of day they eat, therefore, it is

possible that home-prepared food could affect their BMI. Furthermore, the experiment

did not include whether children have health conditions such as hypothyroidism, which

contribute to weight gain, thus it is not known precisely what factors could affect their

BMI. Moreover, health weight range of BMI is in a fairly wide range, in order to take into

account people of different physical characteristics. Nonetheless, like in any other

mathematical formula, BMI calculations have some limitations; people with genetically

determined thick bones tend to have overestimated value of BMI and it does not include

muscle and water mass.

5.5 Sport

Calculations concerning time required to burn average energy value in a school meal are

approximate and in most cases not much useful if they are not verified in practice. It is

due to the fact that every human body is different and they differ from each other in

number of factors, in which the greatest impact is the error in the calculations of the rate

of metabolism and the composition of other body tissues. All the calculations above are

purely theoretical and tentative. Only exercise in controlled laboratory conditions,

where calorimetric energy change, the composition of exhaled air and a number of other

factors are tested, can give accurate values. Counting and burning calories predictions

are useful in the initial planning stage of exercising, but then all of the calculations

should be verified in practice by observing increase and decrease of both fat and lean

body mass, and on this basis, the amount of exercise should be controlled.

5.6 Evaluation

Factor Effect on Experiment Improvement

BMI calculations Due to the fact that BMI Use other body fat

20

calculation does not include bones, muscle and water mass, it is possible that it gave overestimated values.

measurement methods, such as bioelectrical impedance analysis.

Children

Children’s approach towards the questionnaire was trivial, and consequently it gave inaccurate results, therefore children had to re-answer the questionnaire.

Perform a study on children in adolescence.

School meals

Weight of each product was given by those preparing meals, which then affected the accuracy of calculations of the amount of calories a particular product had and therefore the whole amount of calories in school meals.

Measure the weight of each product using weighting scales in order to obtain accurate values.

Bibliography

1. Wiesław Graban, Witold S. Gomułka, Encyklopedia Zdrowia, Wydawnictwo

Naukowe PWN, Warszawa 2001

2. Michael Kent, Oxford Dictionary of Sports Science & Medicine Second Edition,

Oxford University Press 1998

3. http://metromsn.gazeta.pl/Lifestyle/

1,126513,12818816,Polacy_nie_jedza_sniadan__To_niezdrowo__Jak_ich_zachecic.

html

4. http://zdrowie.dziennik.pl/profilaktyka/artykuly/408809,trzykrotnie-wzrosla-

liczba-otylych-dzieci-w-polsce-warszawa-chce-walczyc-z-nadwaga-i-otyloscia-w-

szkolach.html

5. http://www.farmacjaija.pl/zdrowie/co-powinny-jesc-dzieci.html

6. http://children.webmd.com/news/20100315/school-lunches-linked-to-kids-

obesity

7. http://www.cdc.gov/healthyweight/assessing/bmi/childrens_bmi/

about_childrens_bmi.html#What%20is%20BMI%20percentile

21

Appendix 1

22

Appendix 2

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Appendix 3

1. Did you practice sport throughout the week? If so, please specify.

☐ Yes: ____________ ☐ No*

2. How much time have you devoted your time to practice the aforementioned sport?

☐ ______________

3. Did you attend physical education classes this week?

☐ Yes ☐ No

*If you have chosen this answer, you are not obliged to answer next questions.

Appendix 4

Dear __________,

My name is Eleonora U. …………….. and I am a student of International

Baccalaureate program in Szkola Europejska in Lodz. Under this program, I am obliged

to write a research paper of a topic of my interest, which in my case is The Study of

Obesity Among Primary School Pupils in Szkola Europejska. In order to conduct my

research, I need your permission for your child to be medically examined. It would

involve measuring the height and weight of your child and launching of a questionnaire.

All information will be anonymous.

If you agree to have your child examined, please put your signature in

a designated area.

I give my permission for my child to undergo medical examination.

Signature:__________________________________

24

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