The Body Mass Index (“BMI”) is determined by the height and weight. A normal BMI is defined as less than 25, being overweight is defined as a BMI between 25-30, obesity is present when the BMI is between 30-40 and a BMI over 40 is called morbid obesity.
However, the impact of weight on health and the risk for developing weight-related co-morbidities such as diabetes, hypertension, heart disease, cancer, GERD, dementia, etc. is much more related to body composition. An NFL football player that stands 5 feet 11 inches and weighs 220 pounds has a BMI of 30.7 and is therefore in the “obese” category. BUT, that football player most likely has a percentage body fat well below 10%. This person is quite healthy, basically all muscle and is NOT at high risk at all. A 5 feet 11 inch 220 person with a percentage body fat of 42% has the same BMI as the aforementioned football player but yet is very much at risk for life-threatening medical problems due to the weight.
Many people report to us that they have a body composition scale at home and they are happy to report pretty good looking numbers as far as the percentage body fat. “Normal” percentage body fat is defined as less than 30% for women and 25% for men. But here begs the question: How accurate are these home body composition scales?
Numerous studies have shown very poor accuracy of these home composition scales when they are compared to much more expensive impedance plethysmography machines used at hospitals and doctors’ offices. The most “accurate” home machines are off by more than 20% and the least are almost 50% inaccurate.
The bottom line: Home scales are probably quite accurate with measuring your weight, and therefore your BMI can be assessed accurately at home. However, please do not get a false sense of security if your body comp scale at home shows a veery favorable number, as there is a high likelihood that the percentage body fat seen is not very accurate.
Please come in for a FREE body scan on our very expensive INBODY composition machine. The information provided (fat %, muscle mass, body water content) is very valuable to know.
