Bridge

This Newsletter aims to promote communication between schools and the Student Health Service of the Department of Health

July 2010 Issue No.47

Published by the Student Health Service, Department of Health

 

From the Editor

 

Editorial

Hong Kong is a food paradise where we can taste a wide variety of foods. We may have concern about one thing: how can we eat healthy and have good nutrition? Well, the essence is to eat the appropriate amount of food and in a balanced manner, so that we could get adequate calories and nutrition to supply the body's need for growth and daily activities. Calorie is the unit for measurement of energy. The knowledge about calorie helps us adopt a balanced diet.

We often make comparison between the intake and the consumption of calorie. The reason is that if the energy intake from food equals to the energy consumed, there would not be excessive intake. We then can meet the need of our daily life as well as keep our body weight within a desirable range. However, if there is insufficient energy, body growth would be adversely affected. So, how can we apply the concept of "calorie" in daily life? For intake of calorie, the amount would vary with different kinds of food we eat. For consumption, different people would have different energy consumption depending on their age, sex, body weight, daily activity and health status. What we should do is to make a balance between the intake and consumption of energy, in order to lead a healthy living.

In this issue of bridge, our dietitians give us details about calorie and the principles in its application. Hope that it would help us make wise choices, eat happily and stay healthy. You may find more details about healthy eating in the following websites of the Centre for Food Safety and the Student Health Service.

  1. http://www.studenthealth.gov.hk/english/health/health_dn/health_dn.html
  2. http://www.cfs.gov.hk/english /nutrient/index.shtml

Eat healthy and have good nutrition

 

Feature Article - Calorie and its use

Ms Cassie Li, Dietitian
Mr Chui Tung Kin, Dietitian

 

Introduction

People often say, “……losing weight means cutting down calorie, count before you eat… …” In fact, whether we need body weight control or not, we should know about “calorie” and learn how to use it. Appropriate amount of calorie intake, together with balanced nutrition, would help promote our health, increase immunity and supply adequate energy for daily activities.

 

Definition of calorie

Calorie is the unit for measuring energy. There is energy in all foods and drinks (except water). One calorie is defined as the amount of energy needed to heat up one gram of water by one degree Celsius. We may come across various units for quantifying energy such as calorie, Calorie, kilocalorie, Kcal, Joule, kilojoule in publications and on food packages. What do they mean?

“Calorie” (abbreviation is “Cal”) with the capital C does not equal to “calorie” (abbreviation is “cal”) even though their pronunciation is the same. One “Calorie” is equivalent to 1000 “calorie”. We can use “kilo” (abbreviation is k) to express the meaning of 1000. Therefore, 1 Calorie means 1 kcal. When we talk about calorie in our daily life, we actually mean 1 Calorie or 1 kcal.

1 Calorie (1Cal) = 1000 calorie (1000 cal) = 1 kilocalorie = 1 kcal

“Joule” (abbreviation is J) is another unit for measuring energy. It is widely used in some countries. One kcal is equivalent to around 4.184 kJ.

1 kilocalorie (kcal) = 4.184 kilojoule (kJ)

 

How much energy does food contain?

Foods contain energy. The amount of calorie in individual food depends on its composition, namely, carbohydrates, protein, fats and alcohol

  • 1g Carbohydrates ≈ 4 kcal (Calorie)
  • 1g Protein ≈ 4 kcal (Calorie)
  • 1g Fat ≈ 9 kcal (Calorie)
  • 1g Alcohol ≈ 7 kcal (Calorie)

In comparison to carbohydrates, protein and alcohol, fats are the most energy-dense component found in food, with around 9 kcal in every gram of fat. Foods that are high in fat such as deep-fried foods are higher in calorie. For example, the calorie content of vermicelli (rice noodles), which has not been deep-fried before packaging, is lower than instant noodles, which has been deep-fried. Duck with skin removed, has lower energy content than duck with skin by about two-third. The energy of skim milk is lower than full-fat milk by almost half.

Food Weight Energy (kcal)
Instant Noodles 100g 472
Rice noodles (cooked) 100g 109
Duck (with skin) 100g 404
Duck (without skin) 100g 132
Full fat milk 240 ml (1 cup) 154
Skimmed milk 240 ml (1 cup) 84

If you are interested in the calorie of other food items, you may browse the following website:
http://www.studenthealth.gov.hk/english/health/health_dn/health_dn_cvocf.html

 

How much energy do we need every day?

Food supplies the energy necessary for carrying out our daily activities, for example, going to school, doing exercise, growth, breathing and digesting food. Basically, energy expenditure can be divided into 3 types:

1) Basal metabolic rate (BMR). It is the minimum amount of energy expended for sustaining life processes such as heartbeat, breathing, blood circulation.

2) Activity- related energy expenditure (AEE). It is the energy needed for physical activities, for example, walking, football, doing household chores, doing homework.

3) Thermic effect of food (TEF). It is the energy required for digestion, absorption, and metabolism of nutrients.

For adults, if the energy obtained from food equals to the energy expended, the body weight would remain unchanged. If the energy obtained is less than the energy expended, the body weight may decrease. Conversely, if the energy intake is higher than the energy expended, one would become overweight and possibly obese. For children and teenagers, extra amount of energy is needed for growth and development. Therefore, it is very important that they obtain adequate energy for growth and different kinds of activities in daily living.

How much calorie is enough? Different countries have their own reference values to estimate how much energy a person requires per day. Here are two examples of reference values for the average daily energy requirement.

United States – Reference value of average daily energy requirements for individuals (kcal)

Age Weight(kg) *PAL (low) *PAL (Moderate) *PAL (High)
Male Female Male Female Male Female Male Female
6-7 21.7 20.6 1350 1225 1575 1425 1800 1650
7-8 24.0 23.3 1450 1325 1700 1550 1950 1775
8-9 26.7 26.6 1550 1450 1825 1700 2100 1950
9-10 29.7 30.5 1675 1575 1975 1850 2275 2125
10-11 33.3 34.7 1825 1700 2150 2000 2475 2300
11-12 37.5 39.2 2000 1825 2350 2150 2700 2475
12-13 42.3 43.8 2175 1925 2550 2275 2925 2625
13-14 47.8 48.3 2350 2025 2775 2375 3175 2725
14-15 53.8 52.1 2550 2075 3000 2450 3450 2825
15-16 59.5 55.0 2700 2125 3175 2500 3650 2875
16-17 64.4 56.4 2825 2125 3325 2500 3825 2875
17-18 67.8 56.7 2900 2125 3400 2500 3925 2875

*PAL = physical activity level

China - Reference value of average daily energy requirements for individuals (kcal)

  Male Female
Aged 7-10 1950 1850
Aged 11-14 2650 2300
Aged 15-18 2900 2400
Activity Level Low Medium High Low Medium High
Aged 18 above 2400 2700 3200 2100 2300 2700
Aged 50 above 2300 2600 3100 1900 2000 2200
Aged 60 above 1900 2200 N/A 1800 2000 N/A
Aged 70 above 1900 2100 N/A 1700 1900 N/A
Aged 80 above N/A 1900 N/A N/A 1700 N/A
Female: Pregnancy +200 kcal, Breastfeeding +500 kcal

From the above tables, we note that daily energy needs vary among individuals. Children and adolescents in their developmental stages, pregnant women and breastfeeding women require higher calorie intake. Energy needs decline gradually with age (after the age of 18). People with higher physical activity level need more energy. Therefore, we may find out our daily energy requirement from the above tables according to our age, sex, body weight, activity level, etc. However, the values do not indicate the exact energy requirement and the figures are for reference only.

 

How do we apply “calorie” in our daily life?

The use of calorie is widespread.

1) In clinical settings, energy requirement is usually estimated by medical personnel or dietitians to help plan diets for patients with special need, for example, diabetes, on enteral / parental nutritional support, etc.

2) According to the World Health Organization's (WHO) recommendation, about 55% - 75% of our total energy should come from carbohydrates, about 10 - 15% from protein and about 15 - 20% from fats. For example, for an individual who has an energy requirement of 2000 kcal per day; about 1100 - 1500 kcal should come from carbohydrates, about 200 - 300 kcal from protein and about 300 - 600 kcal from fats. It would be good if we can obtain the energy from food in this ratio. However, we also need to follow the principles of a balanced diet in order to achieve a really healthy eating lifestyle.

The principles of a balanced diet are as follows:

  • Eat most - grains or cereals
  • Eat more - vegetables and fruits
  • Eat moderately - meat, poultry, fish, eggs, dry beans and dairy products
  • Eat less- food high in fat/oil, salts or sugar
  • Drink 6 - 8 glasses of fluid (including water, tea and soup) every day

Please check the following website for more details about balanced diet:
http://www.studenthealth.gov.hk/english/resources/resources_bl/files/lf_dn_cpeh.pdf

3) For individuals who are trying to manage their weight, they tend to have high concern about the calorie content in foods. One of the major reasons of overweight is energy intake being greater than energy expenditure. The excessive energy would accumulate and store in our body as fat. Knowing more about calorie content of different kinds of food can help us choose the more appropriate kind of food to eat, thus help in weight control. For example, 100g butter contains 717kcal, 100g peanut butter contains 588kcal and 100g jam contains 255kcal. Undoubtedly, jam's calorie is the lowest among the three. Another example, 100g pork (50% lean) contains 395kcal and 100g pork (100% lean) contains just 143kcal. 100% lean pork obviously contains much lower calorie. It is understandable that the advice from dietitians usually concerns about the controlling of calorie intake. But, is weight management only concern about calorie counting? Let's look at the following diets.

Diet A

  Food Portion Calorie (kcal)
Breakfast Instant Noodles
Soft Drinks
1 portion (~100g)
1 cup (~240ml)
472
97
Lunch Instant Noodles
Soft Drinks
1 portion (~100g)
1 cup (~240ml)
472
97
Afternoon Snacks Crisps 1 packet (~50g) 268
Dinner Instant Noodles
Soft Drinks
1 portion (~100g)
1 cup (~240ml)
472
97
Total energy 1975

Diet B

  Food Portion Calorie (kcal)
Breakfast Wholemeal bread
Egg (boiled)
Skimmed milk
water
2 slices (~100g)
1 (~50g)
1 glass (~240ml)
1 glass (~240ml)
246
78
84
0
Lunch Brown Rice
Spinach
Lean meat
water
1 ½ bowl (~279g)
⅔ bowl (~160g)
~100g
1 glass (~240ml)
327
24
143
0
Afternoon Snacks Apple
Skimmed milk
Plain crackers
water
1 (~138 g)
1 glass (~240ml)
8 (~24g)
1 glass (~240ml)
81
84
104
0
Dinner Brown Rice
Broccoli
Lean chicken
Orange
water
1 ½ bowl (~279g)
⅔ bowl (~160g)
~80g
1 (~121g)
1 glass (~240ml)
327
35
111
59
0
Total oil 6 teaspoons(~30g) 270
Total energy 1973

Diet A and Diet B has similar amount of calorie. Nevertheless, the nutritional value could be very different. Diet B is a well-balanced diet and thus, a healthier choice. Consuming Diet A over a period of time may put one at a higher risk of the following:

  1. Excessive intake of fat and sodium (salt) may increase the risk of cardiovascular diseases and high blood pressure.
  2. Excessive intake of simple sugar may increase the risk of dental caries.
  3. Inadequate intake of vitamins and minerals is likely to affect our general health and may compromise our immune system in the long run.
  4. Inadequate dietary fibers and water intake could cause constipation.
  5. Inadequate protein intake means that our body may not be able to repair our skin and muscle.
  6. Inadequate calcium intake may increase risk of osteoporosis.

On the contrary, Diet B is a healthy and well-balanced diet, with 2 portions of fruits and 3 portions of vegetables every day, and following the principles of the healthy eating. By adopting a healthy diet, the risks of developing chronic illnesses are lowered and our health and general well-being maintained. Therefore, both energy and nutrients are important in weight control. Either inadequate energy intake or nutrient deficiency would adversely affect our health. Needless to say, appropriate amount of exercise is also essential.

 

How do we use nutrition label to choose food?

The law upgrading food labels will become effective on 1 July 2010. It is a mandatory nutrition-labeling scheme for all pre-packaged food (exclude the exempted foods) .The law requires all pre-packaged food to label energy content plus seven core nutrients - protein, carbohydrates, total fat, saturated fat, trans fat, sodium and sugars. Having this information, we can compare different pre-packaged food and choose the healthier options according to our needs.

For individuals who need weight control, they should try to choose foods that are low in total energy, fats, and sugars. With the help of nutrition label, it would be feasible to choose food which is "low energy", "low sugar" or "low salt". According to the food labeling law, the meanings of these nutrition claims are as follow.

Claim Food (per 100g) containing Liquid (per 100ml) containing
Low calorie ≤40 kcal ≤20 kcal
Energy free Not applicable ≤4 kcal
Low fat ≤3g fat ≤1.5g fat
Fat free ≤0.5g fat ≤0.5g fat
Low sugar ≤5g sugar ≤5g sugar
Sugar free ≤0.5g sugar ≤0.5g sugar

We should always compare the nutrient value as well as the calorie content on nutrition labels when we buy pre-packaged food, choose the healthier option and follow the principles of healthy eating. The following website may give more information on calorie and nutrient values of different kinds of food: http://www.cfs.gov.hk/english/nutrient/search1.shtml

 

Conclusion

"Calorie" is a kind of basic nutrition knowledge which helps us choose food. With the help of calorie, we can calculate the amount of calorie intake and calorie consumption. However, we should bear in mind that our aim is to have balanced diet and healthy lifestyle. Besides energy, nutrition is also important in our choice. We should not lose weight or cut down our energy intake too casually. After all, the key to maintaining or promoting our health is to obtain adequate energy and nutrients. For people with special needs such as overweight, underweight, nutrition deficiency, illness, etc., they should seek advice from doctors or dietitians on how to adjust their energy and nutrient intake according to their individual need.

Reference:

The Chinese Dietary Reference Intake, Chinese Nutrition Society 2000

Human Energy Requirements 2004, WHO/FAO

WHO/FA02003

Centre for food safety

Pennington, J.A.T. Bowes and Church's Food Values of Portions Commonly Used. 17th edition. US:

Lippincott Williams & Wilkins, 1998.

 

MY View, Your View

It is very important that we get adequate energy for growth and daily activities. However, if energy intake is greater than energy consumption, the excessive energy would become fat deposit in the body and accumulation of fat would lead to overweight. Therefore, a balanced diet is the key. Appropriate amount of nutrition and calorie would provide sufficient input for the body and would not bring about overweight. Let’s look at our students’ views towards calorie and healthy eating.

  • Calorie is a measure of energy
  • A balanced diet is very important
  • Eat less food or snacks that are rich in calorie content
  • 3 parts of cereals, 2 parts of vegetables and 1 part of meat
  • Take food that is low-sugar and low-fat. Have more physical exercise
  • We have to keep our weight in the desirable range
  • Fruits are healthy snack food because they are nutritious and low in caloric value
  • Both you and me would like to become a healthy person, let’s eat more cereals but less sugar
  • The caloric value of dessert and deep- fried food is very high
  • Eat less deep-fried or fried food, do more physical exercise. The energy intake would not become excessive
  • Choose food carefully, check the caloric value before you buy food
  • Eat less candies, pop- corns, soft- drinks and ice lolly

 

Friends and Health Box

Dear brothers and sisters of Newsletter,

What kind of food do you like? For myself, I like potatoes, Chinese white cabbage, ice- cream, ice-lolly, chestnuts, chestnuts- cakes, mangoes, mango-cakes, cheese cakes, potato chips etc. Are they good for us?

Ying Ying

Dear Ying Ying,

Thank you for your letter. I love to eat a wide variety of foods. Usually I choose healthy ones and take the appropriate amount suggested by the "Healthy Food Pyramid". Among the types of foods mentioned in your letter, I suggest you take more vegetables and fruits. Cakes are rich in sugar, and potato chips are high in fat. Hence, it would be better for you to reduce taking these kinds of foods, so as to prevent too much calorie intake, and not to affect the absorption of other nutrients.

A balanced diet is very important to the physical development of children and adolescents. To achieve this, we must take the types and amounts of food recommended by the “Healthy Food Pyramid”. Cereal should form the bulk of our diet, accompanied by a relatively large amount of vegetables and fruits. A suitable amount of meat, eggs, beans and dairy products is also important. Intake of salt, oil and sugar should be reduced to a minimum. This is what a balanced diet looks like.

Wish you good health.

Health Box

 

Health Tips

Interesting Knowledge Q & A

How many bowls (medium size) of rice would provide the same amount of calorie intake as a chocolate bar (~100gm) would do?

  1. 2 ½ bowl
  2. 1 ½ bowl
  3. 1 bowl
  4. ½ bowl

Answer: a. 2.5 bowl.

The calorie content in one pack of chocolate (100g) is approximately 586 Cal. The calorie content in one bowl of rice (100g) is approximately 236 Cal.

 

Health Tips

Health Drink

It has been claimed that some drinks contain glucose which could quickly restore the energy you consumed. In fact, many foods, such as rice, bread, cereals and sugar would be digested to glucose. Besides, glycogen in the liver would be converted to glucose to supply energy as body needs arise. Therefore, it’s not a must to eat or drink “glucose” for restoration of energy.

 

Health Box

 

For enquiries of student's health problem, please write to "Health Box"

 

Please write your name & address, contact tel. no. in the letter.

 

Health Box

4/F, Lam Tin Polyclinic,

99 Kai Tin Road,

Kwun Tong,

Kowloon

Editorial Board Members:

Dr. TONG Nga-wing, Ms. CHIU Wai- fong, Alice, Ms. CHOI Choi-fung, Ms. LAI Chiu-wah, Phronsie, Ms. CHAN Kin-pui

Tel : 2349 4212 / 3163 4600 Fax : 2348 3968

 
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Last Revision Date : 9 December 2014