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WHAT IS OBESITY?
Obesity is characterized by the accumulation of an excessive amount of fatty or adipose tissue. Obesity results from unbalanced energy budgets. An overweight person consumes food energy in excess of expenditure and stores the surplus in body fat. The presence of this excess fat impairs the functioning of many important organs and body systems and can lead to multiple health problems, even death.
Excess body fat has been linked to a long list of adverse health problems including cardiovascular disease, diabetes, high blood pressure, cancer, arthritis, gall bladder disease, and certain reproductive disorders.
Health practitioners acknowledge that obesity is prevalent enough to be considered a serious health concern. It is estimated that nearly 10-12% of adults (30 million people) are obese and perhaps up to 50% of adults have a weight problem.
One method used to measure obesity is the determination of body fat content, or body compositional analysis. For adult males, obesity has been defined as having a body fat content greater than 25% of total body weight. For adult females, having a body fat content of 30% or greater is considered obese.
The recommended body fat content for males is 15-18% of total body weight and the recommended body fat content for females is 20-25% of the total body weight. Percentages vary with age. With increasing age, fat percentages rise in both males and females, reaching 30-40% of the total body weight.
There are a number of methods used to measure body fat percentages. There is the skin-fold thickness or "caliper test". This test measures the thickness of the skin at various locations in the body to estimate body fat content. Underwater weighing techniques are known to be the most accurate method of measuring a person's body fat content, but these techniques are not widely available. However, a new technology that measures the movement of electrical impulses through body tissue (electrolipograph) provides a highly accurate estimate of body fat percentage. At this time this technique is only available at select medical clinics and centres.
Another popular technique for estimating body fat content is derived from one's height and weight. This technique is used most frequently because of the ease of measuring height and weight. The primary weight/height based measurement is the body mass index (BMI). This technique correlates closely with percent body fat. The BMI is calculated by measuring a person's body weight in kilograms and then dividing by the person's height in metres squared (kg/m2). According to the National Institutes of Health (Bethesda, MD), obesity is defined as a BMI greater than 30. As the BMI increases, so does the level of risk for health problems. A BMI of 20 to 25 is ideal, with the lowest health risks.
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