Obesity

A person gains weight if he eats more than what his body uses, whether due to little physical activity or a low basal metabolic rate. People in a society tend to become obese as soon as enough food and leisure are available to cause an imbalance, with more energy intake and less energy expenditure. Sustained caloric imbalance with consequent obesity is becoming the behavioral norm. Its prevalence is increasing in all major race/sex groups including younger adults aged 20-45 years.

Obesity tends to occur more frequently in some families than in others. This may indicate a hereditary tendency or it may be due to shared food consumption patterns and attitudes towards food. Women tend to gain weight after menopause while men tend to at middle age. Men are more likely than women to be overweight (BMI 25-29.9), while it is women who comprise the majority of the obese and severely obese (BMI >30). There is evidence that an increasing number of children and adolescents are overweight. Even though all overweight children will not necessarily become overweight adults, the increasing prevalence of obesity in childhood is likely to be reflected in an increasing number of obese adults.
Obesity is therefore becoming a more important risk factor. It has been linked statistically to high blood pressure, diabetes, cardiovascular disease and chronic back and joint pains. It is a serious condition that can shorten the life span.

OBESITY HAS ADVERSE EFFECTS ON HEALTH

Clinical observations have long suggested a connection between obesity (particularly in its extreme forms) and a variety of illnesses. Obesity creates an enormous psychological burden. In fact, in terms of suffering, this burden may be the greatest adverse effect of obesity. An increase in body weight of 20% or more above the desirable body weight constitutes an established health hazard and shows an overall increase of 20% in the likelihood of death from all causes.
Obesity is associated with an increased incidence of the following conditions:

• Diabetes Mellitus.
• High blood pressure.
• High blood cholesterol.
• Coronary artery heart disease.
• Stroke.
• Back problems
• Cancer of the colon, rectum, prostate (in men), or breast, cervix or uterus (in women).
• Gall-bladder disease.
• Pulmonary abnormalities (Pickwickian syndrome or the obesity-hypoventilation syndrome) causing a decrease in expiratory reserve volume and a likely reduction in all lung volumes. In addition, respiratory muscles may not function normally in obese individuals.
• Osteoarthritis (inflammation of a joint due to the wearing out of the cartilage that lines it).
• Reduced physical endurance.
• Psychological problems, low self-esteem. Discrimination against obese persons is common in both academic and work settings. Impairment of body image is the major form of psychological disturbances specific to obese persons.

INDICES OF OBESITY

In the past, obesity was often measured by "desirable" or "relative" weight. Desirable weights are based on weights of people associated with the lowest mortality, i.e. predominantly upper middle class individuals. Relative weight is calculated by dividing the patient's weight by a standard weight that is based on the patient's height, age and sex. There are several problems with the appropriateness of these two measures. They are not applicable to the entire population. Frame size is subjectively determined. A newer, more clinically useful measurement, is the so-called Body Mass Index (BMI). The BMI is obtained by dividing the weight in kilograms by height, measured in meters, squared (W/H2). Identical standard values can be used for all adult patients, both men and women. The ideal BMI should be 20-25 kg/m2.

ASSESSMENT OF BODY FAT

To determine whether an individual is obese or simply overweight because of increased muscle mass, one needs techniques for quantitating body fat. Skinfold measurements can be used to measure body fat. Approximately half the fat in the body is deposited in the skin. The percentage of internal fat increases with increasing weight. Skinfold measurements are often not accurate or reproducible, especially if the one conducting the test is inexperienced. Skinfolds are not equally compressible and skin thickness is not necessarily constant. More precise and technically sophisticated methods for determining body fat include underwater weighing, which requires total submersion of an individual and an accurate estimation of lung and abdominal gas, the assessment of total body water by dilution of tritiated water, and measurement of body fat by dilution of an inert fat-soluble gas such as Xenon. CT, ultrasound, and MRI have also been used to determine body fat. However, these measures are all expensive, difficult to do, time consuming and not applicable to normal practice.

      WHAT YOU CAN DO

WHAT YOUR DOCTOR CAN DO FOR YOU?

• Determine the cause of obesity and treat it.
• Treat the complications.
• Refer you to a dietitian.
• Refer you to a psychiatrist for behaviour modification therapy.
• Check for contraindications to a weight control and aerobics program.
• In extreme cases, recommend surgery (e.g. liposuction or gastric stapling). However, the cost of the operation and the inherent dangers of any surgery make this a treatment to be used only as a last resort.

WE CAN CONTROL BODY WEIGHT

It is particularly important for parents to teach their children good eating habits and to control any tendency toward obesity before it becomes a serious problem. Older people, too, need to take special care to avoid obesity. They tend to be less active than in their younger days, yet may continue to follow their established eating patterns.
Percentage of overweight population in Singapore

• Enlistees = 7-10%
• Active servicemen = 13%
• Nsmen = 20%
• General population = 25%

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