Body Mass Index (BMI) vs. Body Composition: These measurements are used in the healthcare and corporate fitness worlds to help identify risk for heart disease, diabetes, stroke, and cancer. But which is best? Many experts reason that both tools can be useful in different circumstances.
BMI is calculated by dividing weight (kg) by height (m²). Although it takes into account only these two factors, it can generally identify levels of fatness in most people, and has more of a place when a simple, general assessment of a larger group is needed. Labels of “underweight,” “healthy,” “overweight,” and “obese” are used to describe BMI ranges.
The drawbacks of BMI are manifested in a couple of ways. Someone who possesses a great amount of muscle mass may be classified as overweight or obese, when in reality they are in superior shape. An unconditioned individual can be classified as being at a healthy weight when muscle mass is actually lacking. This is where measuring body composition is valuable.
Body composition separates fat mass from lean mass and provides a better assessment of an individual’s health status. The limitations of body composition are that it’s not quite as simple and may not be practical for use in assessments of large groups. The simplest means of measuring it are by scale, handheld device, or skinfold testing and include some margin of error. While most accurate, underwater weighing or air displacement can be complicated and time consuming.
When embarking on a fitness program, it’s a good idea to track your body composition to help you measure your progress. This will allow you to have a much better idea of how your body is changing for the better with the effects of resistance training and cardiovascular exercise.