Obesity is becoming more prevalent in the United States. According to the National Institute of Diabetes Digestive and Kidney Diseases, 66 percent of Americans are either overweight or obese. These terms carry different stipulations, but both are considered unhealthy.
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According to "Physiology of Sport and Exercise" by Jack Wilmore and David Costill, obesity can be classified using body fat percentage or body mass index. A man is considered obese when he has a body fat percentage greater than 25 percent and a woman when her body fat percentage exceeds 35 percent. Body mass index, or BMI, is an estimation of relative body weight and composition based on your height versus weight. According to the American College of Sports Medicine, if your BMI is equal to or greater than 30, you are obese.
There are several ways to assess your body fat percentage, but the most accurate is hydrostatic weighing, according to Wilmore and Costill. This method compares your weight on a scale to your weight while under water. A dual-energy X-ray absorptiometry scan is a machine that scans the entire body and assesses soft and hard body composition. It can give an accurate total body fat reading. Skinfold techniques involve separating the fatty layer from the lean layer on areas around your body. The measurements are entered into an equation and body fat is estimated. Bioelectrical impedance measures body fat by sending a small current through your body; since lean muscle tissue will conduct the current, body fat can be measured by the current that is returned.
Body Mass Index
The above methods of calculating your body fat percentage require special equipment or professional assistance. Identifying body mass index is done by comparing height versus weight, but according to the National Institute of Diabetes Digestive and Kidney Diseases, BMI cannot be completely accurate because it is not a direct measurement of lean body mass. To estimate your BMI, divide your weight in kilograms by your height in meters squared, explains "Physiology of Sport and Exercise." A health BMI falls between 19 to 24.
Obesity puts you at increased risk of developing heart disease, respiratory problems, fertility problems, osteoarthritis, liver disease and many psychological problems, according to the National Institute of Diabetes Digestive and Kidney Diseases. An unhealthy lifestyle can lead to obesity, but you might also be at risk of becoming obese if you have a family history of obesity or certain diseases, like hypothyroidism.
If you want to avoid becoming obese, you must be proactive. Behavioral changes regarding diet and exercise will help you maintain a healthy weight. According to the American College of Sports Medicine, an obese person trying to lose weight should undertake 150 minutes of moderately intense exercise per week. For a healthy person wanting to maintain his weight, he should perform 60 minutes of moderate-intensity exercise three to five days per week. For diet, you should choose healthier foods like increasing whole grains, fruits and vegetables.
An obese person is at an increased risk of orthopedic injury because of the increased pressure on joints, muscles and connective tissue. According to the American College of Sports Medicine, cardio exercise that is non-weight bearing, like bicycling or swimming, can be done to start. In addition, a lower intensity might be required until cardiovascular fitness improves. When designing your exercise program, place an emphasis on total caloric burn through intensity and duration of activity.
REFERENCES & RESOURCES
- National Institute of Diabetes Digestive and Kidney Disease: Understanding Adult Obesity
- "Physiology of Sport and Exercise"; Wilmore, Jack H., Costill, David L.; 2004
- "ACSM's Guidelines for Exercise Testing and Prescription"; Whaley, Mithcell H., PhD, Brubaker, Peter H., Phd, Otto, Robert M., Phd (Eds.); 2006.
- Mayo Clinic: Obesity