Diet and Nutrition

Obesity and Health

Definition of obesity

Overweight (including obesity) is defined as weight exceeding 120% of the median weight-for-height. (please refer to the table below)

Body Mass Index is used for male students with height > 175cm and female students with height > 165cm. BMI > 25 indicates overweight.

Height(cm) Weight-for-Height
Median x 120%
91 12.9 15.5
101 15.4 18.4
111 18.3 21.9
121 22.1 26.5
131 26.9 32.3
141 33.1 39.7
151 40.4 48.5
161 48.5 58.2
171 56.7 68.0
Height(cm) Weight-for-Height
Median x 120%
91 12.9 15.5
101 15.2 18.2
111 17.8 21.4
121 21.4 25.7
131 26.5 31.7
141 33.3 39.9
151 41.6 49.9
161 50.3 60.4
165 53.5 64.2

Source: Hong Kong Growth Survey 1993

Causes of obesity


Excessive energy (calorie) intake

  • binge eating
  • frequent intake of high sugar or high fat food
  • frequent dine out and choose high calorie food
  • bulimia or other eating disorders led by emotional problems

Decreased energy expenditure, lack of exercise

  • sedentary lifestyle e.g. watching TV, playing TV games / computer games
  • too much homework, use of leisure time for study
  • parents do not encourage children to do physical activities or cannot spare time to arrange physical activities for their children

Others e.g. hereditary factors, effects of illnesses or drugs

Impact of obesity


Physical aspect

  • may increase the workload of different organs of the body leading to various illnesses and a shortened lifespan. There is an increased risk of diseases like hypertension, heart disease, stroke, diabetes, back pain, sleep apnea, gall stone, hernia, osteoarthritis

Social aspect

  • may be clumsy and slow, cause exercise intolerance
  • have no enthusiasm for school events or sports activities
  • may be teased or isolated by classmates and friends

Psychological aspect

  • may lack confidence in one's appearance resulting in a poor self-image

Prevention of student obesity

  • Student
    * be determined to stop binge eating and control the desire for food
  • Parents
    * know more about food; understand that being fat does not necessarily mean good health or blessing
    * adopt healthy eating habits to be a good example to children
  • School
    * tuck shop should avoid selling high calorie food and drinks e.g. chicken wings, soft drinks
    * supply healthy lunch boxes with less meat and oily food

Essential factors in weight control

  1. Overweight students and their parents have to acknowledge that it is essential to lose weight and set out a weight control plan together
  2. Adopt a healthy lifestyle and good eating habits in the family. Parents and other family members should strongly encourage children to use their determination and confidence to develop good eating habits and increase exercise level. Do not spoil them and meet all their demands
  3. Measure students' weight and height regularly in order to increase one's confidence during weight control
  4. Teach student how to express their emotions appropriately

Weight control tips


Encourage students to follow the Healthy Eating Food Pyramid to eat various kinds of food in the right proportion. Develop a healthy eating habit and avoid picky eating.


Avoid eating too much meat and high sugar or high calorie food or drinks including :

  • deep fried food e.g. French fries, potato chips, fried chicken
  • high fat meat e.g. luncheon meat, fatty meat, preserved meat, animal skin
  • snacks e.g. instant noodles, cup noodles, sausages, chicken wings
  • sugary food or drinks e.g. candies, chocolates, cakes, desserts, ice-cream, soft drinks, juice cartons, bubble milk tea
3. Choose low calorie snacks e.g. fruits, cherry tomatoes, skimmed milk, boiled corn, chestnuts

Cooking tips

  • marinate ingredients with less sugar, oil and sauces
  • steam, stew, simmer or boil instead of frying or deep-frying the ingredients
  • remove animal skin and fatty meat before cooking
  • avoid cooking large pieces of meat e.g. whole drumsticks, chicken wings, pork chop and steak; eat sliced, shredded or diced meat instead to reduce the amount of meat intake
5. Eating habits
  • evenly distribute breakfast, lunch and dinner every day, don’t skip breakfast
  • avoid eating late night supper
  • have regular meal at regular times; chew food thoroughly
  • avoid watching television, reading or playing games at meal times
  • avoid adding condiments e.g. tomato ketchup, salad dressings
  • avoid eating animal skin and fatty meat

Make lifestyle changes

  • avoid lingering in candy stores or the junk food area of supermarkets
  • avoid buying junk food
  • avoid frequent dine out in restaurants or fast food shops
  • when eating out, choose low fat food e.g. noodles in soup, rice with roast chicken (with skin removed), boiled potatoes
  • develop good hobbies such as reading and drawing to avoid eating snacks when being idle

Increase the burning of calories

  • do appropriate amount of exercise regularly to reduce the accumulation of fat and control the body weight effectively
  • take part in extra-curricular activities or leisure classes
  • assist in the housework

Remember :

  1. Prevention is better than cure. The risk of developing chronic diseases can be reduced by weight control.
  2. Place emphasis on long-term weight control and maintenance of good health instead of short-term weight loss. This can be achieved by developing good eating habits and a healthy lifestyle.

(Revised in May 2021)

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