Body Mass Index

Body Mass Index

Body Mass Index (BMI) is an assessment of body weight relative to one’s height. An elevated BMI has increased risk factors for many diseases, such as cancer, hypertension, diabetes mellitus, hypercholesterolemia, and atherosclerosis. Also, a higher BMI may increase the risk for a premature death. A healthy BMI is 21.0 – 24.9 kg/m. A BMI of at least 25 kg/m indicates obesity and an increased health risk. A BMI of 30.0 kg/m indicates grade II obesity, while 40.0 kg/m and greater is morbid obesity.

Body Mass Index (BMI) can easily be used to help establish a client’s fitness program, because it is simple to administer and the results are generally reliable. The BMI may not apply to some individuals with above normal muscle mass, such as bodybuilders.

BMI is the preferred body composition assessment for the obese population. Fat calipers lose their accuracy with large skin folds and variance in fat density. Bio-impedance and near-infrared typically underestimate body fat percentage in this population. Although the BMI doesn’t account for body fat percentage, it is not necessary because excess body fat is already known in the obese.

BMI correlates with body fat. The relation between body fat and BMI differs with age and gender. Women are more likely to have a higher percentage of body fat than men with the same BMI. Older adults may have more body fat than younger adults with the same BMI. For personal trainers, it is important to remember that athletes/bodybuilders may register a high BMI because of increased muscularity, not increased body fat.

BMI measures your weight in relation to your height, and is closely associated with measures of body fat.

The chart above applies to all adults. The higher weights in the normal range apply to people with more muscle and bone, such as men. Even within the normal range, weight gain could increase the risk for health problems.

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