Diet and Nutrition

Obesity and Health

Definition of obesity

Overweight (including obesity) is defined as Body Mass Index (BMI) exceeding 91st percentile line among students of the same sex and age group.

For students who aged 18 years or above, a BMI between 23 and 24.9 indicates overweight. A BMI of 25 or above is obese.


BMI

Male  
Age(years)
BMI
Overweight Obesity
> 91st percentile line > 98th percentile line
6 17.6 19.7
7 18.2 20.7
8 18.8 21.9
9 19.6 23.2
10 20.4 24.4
11 21.2 25.5
12 21.9 26.6
13 22.6 27.5
14 23.3 28.4
15 24 29.2
16 24.7 30
17 25.3 30.7
Female  
Age(years)
BMI
Overweight Obesity
> 91st percentile line > 98th percentile line
6 17.2 18.9
7 17.6 19.7
8 18.2 20.6
9 18.9 21.7
10 19.7 22.8
11 20.5 23.9
12 21.3 24.9
13 22.1 25.8
14 22.8 26.6
15 23.5 27.4
16 24.1 28.1
17 24.7 28.7

Source: Hong Kong 2020 Growth References

Causes of obesity

1.

Excessive energy (calorie) intake

  • binge eating
  • frequent intake of high sugar or high fat food
  • frequent dine out and choose high energy food
  • bulimia or other eating disorders led by emotional problems
  • frequent intake of sugary drinks
2.

Insufficient energy expenditure, lack of exercise

  • sedentary lifestyle e.g. watching TV, playing video/ computer/ online games, internet surfing
  • 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 with their children
3.

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

Impact of obesity

1.

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, fatty liver, osteoarthritis
2.

Social aspect

  • exercise intolerance
  • have no enthusiasm for school events or sports activities
  • may be teased or isolated by classmates and friends
3.

Psychological aspect

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

Prevention of student obesity

  • Student
 * avoid binge eating
* control the desire for food
  • Parents
 * know more about food; understand that being fat does not mean good health or blessing
* adopt healthy eating habits to be a good example to children
  • School
 * tuck shop should avoid selling high energy food and drinks, e.g. deep-fried 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 control 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 have determination and confidence in developing good eating habits and increasing 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

1.

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
2.

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

  • deep fried food e.g. French fries, potato chips, deep-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, carton drinks, bubble milk tea
3. Choose lower energy snacks e.g. fruits, cherry tomatoes, skimmed milk, boiled corn, chestnuts
4.

Cooking tips

  • marinate ingredients with less sugar, oil and sauces
  • steam, stew, simmer or boil instead of frying or deep-frying the ingredients
  • remove poultry skin and fat from meat before cooking
  • avoid cooking large pieces of meat e.g. whole chicken legs/ wings, pork chop and steak; cook 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/ computer / phone, reading or playing games at meal times
  • avoid adding condiments e.g. tomato ketchup, salad dressings
  • avoid eating animal skin and fatty meat
6.

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
7.

Increase energy expenditure

  • 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 September 2024)

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