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Obesity prevention and dietary advice

Causes and Health Impacts of Obesity

What Are the Causes of Obesity?

Weight management may seem to be mysterious to many people but the main cause of weight problems is actually very simple and straight-forward - it is the imbalance between the input and the output of energy:

Input (Energy intake) > Output (Energy expenditure)
Weight Gain (Extra energy stored as body fat)

Energy Intake

Mainly obtains from foods and drinks, however, excessive energy intake can be caused by frequent consumption of high-fat or high-sugar food, and inadequate consumption of fibre-rich foods such as fruit, vegetables, whole-grains and beans. Other psychological or behavioural problems may also lead to overeating.

Energy Expenditure

Energy is required for basic metabolic functions of the body such as heartbeat, breathing and regulation of body temperature as well as our daily physical activities. Sedentary lifestyle and lack of exercise increase the risk of obesity by lowering the energy output of our body.

Other Factors

  • Age: Risk of obesity tends to increase with age.

  • Genetic factor: Weight may be influenced by genes as well as similar lifestyles held by other family members.

  • Ethnic: Risk of obesity and associated complications may also be affected by ethnicity.

What are the health problems caused by obesity?

The health impacts of obesity have been widely studied. It has been found that the mortality rate increases with the severity of obesity. Obesity also increases the risk for a number of chronic diseases, such as hypertension, heart diseases, hypercholesterolaemia, diabetes mellitus, cerebrovascular disease, gall bladder disease, osteoarthritis, sleep apnoea and some types of cancer (e.g. breast, prostate, colorectal and endometrial). 

Dietary Advice to Prevent Obesity

People always talk about "calorie" when it comes to obesity. What does it exactly mean?

"Calorie" is the measurement unit of energy. A calorie (cal) is the amount of energy needed to raise the temperature of one gram of water by one degree Celsius. On the other hand, the energy content of food is often expressed in "kilocalorie (Kcal)" which is equivalent to 1,000 calories.

What determines the amount of energy we need?

The daily requirement of energy varies among individuals. It depends on various factors such as:

  • Growth: Infants, children and adolescents have increased energy requirement due to rapid growth. Pregnant and lactating women also need extra energy for fetus growth and breast milk production.

  • Body composition: A muscular and lean body has higher energy requirement since muscles burn more energy than fat tissues do.

  • Age: Older people in general have a lower metabolic rate and energy need due to changes in their body compositions and hormones.

  • Gender: Men usually have a higher metabolic rate and energy requirement than women as most men have higher percentages of lean muscles and lower percentages of body fat.

  • Job nature and activity level: The more physically active we are, the more energy we need to sustain our activities.

What are some advice for us to avoid eating too much fat and energy?

When you shop ...

  • Buy fresh food whenever possible. Canned and processed products are often added with a lot of sugar or oil or use of fatty food which is energy dense.

  • Choose lean cuts of meat and avoid meat with high fat content such as belly meat and short ribs.

  • Buy plenty and a variety of vegetables. Eating more vegetables can bulk up to your dish and fill up your stomach so that you are less likely to overeat as a whole. The recommendation is to eat at least 3 servings (about 240 grams or 6 taels) of vegetables every day.

  • Choose low-fat or skimmed milk, low-fat dairy products, salad dressing, etc when you shop.

When you cook ...

  • Trim all visible fat from meat or remove the skin from poultry before cooking. Drain any fat accumulated after cooking meat.

  • Try to make your dishes by low-fat cooking method such as steaming, stewing, braising, boiling or stir-frying with small amount of oil.

  • Reduce the amount of oil used in your dishes by adding sauces made from low-fat ingredients such as corn starch with water or light broth.

  • Choose healthy vegetable oils and avoid animal fats such as butter and lard. Although both types of fats contain the same amount of energy, animal fats are rich in saturated fat which may cause elevated blood cholesterol level and increased risk of cardiovascular disease.
  • Remove fat and oil from soup.

When you eat out ...

  • Choose vegetable soup or broth instead of cream soup, because the latter is high in fat.

  • Finish soup and eat your vegetables first so that your stomach is filled. This can pevent you from over-eating meat and grains.

  • Reduce the use of sauces with significant amount of fat such as gravy and cream sauce.

  • Reduce the use of fatty meat, poultry skins and offals which are high in animal fats and cholesterol.

  • Watch out the portion of meat which is sometimes served over-sized in restaurants. On average an adult only needs about 5 to 8 taels of meat (or alternatives including poultry, seafood and egg) every day.

  • Reduce the use of fried rice or noodles. Try not to eat meat or grains added with gravy or sauce with animal fats.

  • Ask for drink with no added sugar. That can reduce your intake of sugar and energy.

  • Use as little condiments as possible. Salad dressings, ketchup and chilli sauce can increase the fat and energy to your food.