As a growing number of people experience weight-related health issues, it has become more important to design diet and exercise programs tailored to individuals' needs. Assessments such as BMI (body mass index) and BF (body fat percentage) can be used to determine health risks associated with disproportionate body composition, as well as to serve as baseline measurements against which progress can be monitored.
The Facts
BMI and BF are both commonly used to classify individuals' level of health. BMI compares an individual's body weight in relation to height and is measured as kg/m2. Alternatively, BF measures the amount of fat, or adipose, tissue in relation to overall weight. It tells a person exactly how much of her weight is composed of fat mass and how much is made up of lean muscle mass. BF can be measured using various protocols, including skin fold measurement, bio-electrical impedance, hydrostatic weighing and DXA scan.
Significance
According to the American College of Sports Medicine, individuals with a BMI of 25 kg/m2 or more are classified as overweight, and those with a BMI of 30 kg/m2 or more are classified as obese. Females with a BF of 29 percent or more are considered overweight, while those with 35 percent or more BF are classified as obese. For males, BF of 20 percent or more is considered overweight, and 25 percent or more is obese. A high BMI or BF puts an individual at elevated risk for chronic diseases, including hypertension, diabetes, cancer and heart disease.
Considerations
BMI does not measure the amount of FFM (fat free mass) an individual has. This tends to skew the usefulness of BMI for athletes and some healthy individuals with a high amount of lean muscle mass, because their overall weight measures high in relation to their height according to the BMI scale. As noted by the American Heart Association, "Some well-trained people with dense muscle mass may have a high BMI score but very little body fat. For them, the waist circumference, the skin fold thickness or more direct methods of measuring body fat may be more useful measures."
Benefits
BMI and BF are useful tools used by health and fitness professionals looking to assess patients and clients. Both are concrete measurements that can be tracked to monitor progress, especially for those who are at high risk and those embarking on a new diet or fitness program to improve their health. As a person loses excess fat, his BMI and BF will decrease, lowering health risks.
Expert Insight
Schedule a DXA to get the most accurate measure of your body composition. DXA uses x-ray technology to measure body fat, muscle and bone mineral density. It requires no removal of clothing, is non-invasive, and provides an x-ray image illustrating exactly how much fat is stored in each region of the body. As of 2010, it is the gold standard in measuring body composition.
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