Abstract

When working with individuals struggling with weight problems, measuring body fatness or the percentage of total mass that is body fat (or percentage body fat (PBF)) is an important part of assessing obesity and determining individual health risk. Current guidelines established by the National Institutes of Health (NIH) and the World Health Organization (WHO) suggest that an adult woman or man who has a body fat percentage exceeding 35% or 25%, respectively, is obese. Obesity is associated with a number of health risks, including but not limited to higher death rates and higher rates of cardiovascular diseases (e.g., heart disease, high blood pressure, high blood cholesterol, and stroke), diabetes and insulin resistance, gallbladder disease, some cancers (e.g., breast, colon, and endometrial), sleep apnea, osteoarthritis, and fertility problems. Because excess body fat is considered the most important indicator of obesity, measuring it directly would be ideal. There are a number of methods for measuring excess body fat, such as dual energy x-ray absorptiometry (DEXA), underwater weighing, magnetic resonance imaging, and bioelectrical impedance. Using these tools, the direct determination of total body fat and PBF can be made very accurately. Unfortunately, these methods often are very expensive, time consuming, and impractical for many clinical settings. Excess body weight alone can provide somewhat of an estimate for excess body fat and would work well if all people were die same height. However, because people vary in height, we must have some way of estimating body fatness using weight adjusted for height. The body mass index (BMI), sometimes referred to as Quetelet’s Index, is the ratio of body weight (in kilograms), to height (in meters, with the value squared) and is used now as the standard for determining obesity. Einleitung