The more body fat you have, the higher your chances of developing chronic health problems. Now there's a new way to measure your risk.
If you are overweight, you are actually "overfat." You are carrying around too much body fat. The body mass index (BMI) is a formula based on height and weight that is used by health professionals and fitness experts to calculate body fat. According to the National Heart, Lung, and Blood Institute, normal BMI scores range from 18.5 to 24.9. If your BMI Is between 25 and 29.9, you are considered overweight. If your BMI is 30 or above, you are considered obese.
Combined with other factors, BMI has long been considered a valuable measure of obesity and a tool to help determine the risk of developing medical disorders such as high blood pressure, type 2 diabetes, gallstones, heart disease, and breathing problems. The higher your BMI, the higher your risk of these and other chronic conditions.
The problem with using BMI as a measure of fitness or fatness, is that it is not consistent for all men and women or across all ethnic groups, and it doesn't differentiate well between lean mass and fat mass, so it is not always accurate. A formula such as BMI, based only on height and weight, can underestimate body fat if you are sick or elderly, or overestimate body fat if you are especially muscular.
In an article published in the May 2011 issues of Obesity, researchers from the Keck School of Medicine at the University of Southern California proposed a new formula for measuring body fat using hip circumference and height. This formula is known as body adiposity index, or BAI. The researchers feel that hip circumference correlated with height gives a much more accurate measure of body fat than weight and height. Since you don't need a scale to measure BAI, this new formula could be especially useful in situations where scales are unavailable.
Unlike BMI, however, which is accessible to anyone who can look it up online or in a fitness reference book, BAI is determined by a slightly more complicated formula that is not as user-friendly, especially for those who are not used to converting their height, weight, and hip measurements into metric form before making calculations. BAI is currently most useful to researchers and medical professionals, who not only can calculate the formula, but who can also best interpret the results by taking other individual factors into consideration. BAI may prove to be a more precise measure of body fat for some people than BMI, but much more research has to be done to determine if BAI is actually a more accurate predictor of good health.
Sources:
Bergman RN; "A Better Index of Body Adiposity." Obesity. May 2011;19(5):1083-9. Web. 26 July 2011
http://www.ncbi.nlm.nih.gov/pubmed/21372804
http://www.nature.com/oby/journal/v19/n5/abs/oby201138a.html
Interactive Mathematics: BAI Calculator with BMI Comparison
http://www.intmath.com/functions-and-graphs/bmi-bai-comparison.php
National Heart, Lung and Blood Institute: Assessing Your Weight and Height
http://www.nhlbi.nih.gov/health/public/heart/obesity/lose_wt/risk.htm
National Heart, Lung and Blood Institute: Calculate Your Body Mass Index
http://www.nhlbisupport.com/bmi/
