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OVERWEIGHT AND OBESITY
Obesity and overweight have become epidemic. Sixty-four percent of Ameri-cans are overweight or obese. Data from the National Center for Health Statistics show that 73% of adults 20 years old and older are overweight or obese.
The percentage of overweight children and teens has tripled in the last 25 years and currently is 40.8%. Overweight puts extra strain on the heart, lungs, muscles, bones, and joints, and it increases the susceptibility to diabetes mellitus and hypertension. It increases surgical risks, shortens thelife span, causes psychosocial problems, and is associated with heart disease and some forms of cancer.
There is no one cause for excess weight, but poor diet and inactivity appear to be leading factors. Genetic, physiological, metabolic, biochemical, and psycho-logical factors can also contribute to it. Energy imbalance is a significant cause of overweight. People eat more than they need. Excess weight can accumulate during and after middle age because people reduce their level of activity andmetabolism slows with age. Consequently, weight accumulates unless calorie intake is reduced. Hypothyroidism is a possible, but rare, cause of obesity. In this condition, the basal metabolic rate (BMR) is low, thereby reducing the number of calories needed for energy. Unless corrected with medication, this condition can result in excess weight.
There are two popular theories about weight loss: the fat cell theory and the set-point theory. According to the fat cell theory, obesity develops when the size of fat cells increases. When their size decreases, as during a reducing diet, the individual is driven to eat in order for the fat cells to regain their former size. Therefore, it is difficult to lose weight and keep it off.
According to the set-point theory, everyone has a set point or natural weight at which the body is so comfortable that it does not allow for deviation. This is said to be the reason why some people cannot lose weight below a “set point” or why, if they do, they quickly regain to that “set point.” The only way to lower a set point is through exercising three to five times a week.
Not everyone fits the USDA weight table shown in Table 16-2 or the “healthy weight target,” which is a BMI of 18.5 to 25. For anyone with a BMI of 25 or higher, a more realistic approach would be a reduction of one or two BMI points to reduce health problems and disease risks. After this loss has been maintained for 6 months, further lowering of the BMI needs to be attempted. A “healthy weight” may be the weight at which one is eating nutritiously, is exercising, has no health problems, and is free from disease.
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