Why you shouldn’t rely on your BMI

BMI, Body Mass Index

By pH health care professionals

Olympian Kerri Strug. NBA player Yao Ming. Actor Peter Dinklage. Model Twiggy. People come in all shapes and sizes, yet doctors have been taught to measure them all the same way for the last 40 years. Yes, we speak of the infamous BMI, or body mass index.

What is BMI, besides that number the doctor pointed at while she was telling you to stop eating so many donuts? It's simply your weight (kg) divided by your height (meters) squared. In the 1800s, a Belgian named Adolphe Quetelet gathered a couple hundred Belgians and weighed and measured them, eventually concluding that the BMI equation was representative of the standard human build.

Epidemiologists picked up the equation in the 1970s as obesity's link to chronic disease became more apparent, and health insurance companies were searching for a way to predict who would be high risk. A large study of over 7,000 people validated that Quetelet's equation was a predictor of body fat percentage on a population level. 

But then, doctors started applying BMI to individual patients. Male, female, muscular, tall, short -- everyone got measured the same way. There are even billing diagnosis codes linked to BMI; your visit gets coded one way if you are "overweight" and another if your number qualifies as "obese." 

BMI has led to countless wasted hours in the form of exam-room arguments. Providers are sometimes so buried in the medical chart that they fail to notice an "obese" patient is actually quite muscular.

People of different ethnicities distribute fat differently; a South Asian woman with a normal BMI might actually have a dangerously high level of visceral fat (wrapped around the abdominal organs), increasing her risk for heart disease. Without measuring her waist circumference, her doctor might end her physical with "you're fine, see you in a year."

Thankfully, some doctors are now turning to other means of assessing a person's health risks from weight, such as observing how their clothes fit, how damaged their joints are from supporting excess weight, or measuring waist circumference.

At pH Labs, we use the latest body composition analysis device, the InBody 720, to measure your body fat percentage, intracellular and extracellular water, and muscle mass. Taking your gender and age into account, we go beyond BMI to help you understand whether you need to build muscle, lose fat or both, so you can be your healthiest self.

Enjoy Your Healthy Life!

The pH professional health care team includes recognized experts from a variety of health care and related disciplines, including physicians, attorneys, nutritionists, nurses and certified fitness instructors. This team also includes the members of the pH Medical Advisory Board, which constantly monitors all pH programs, products and services. To learn more about the pH Medical Advisory Board, click here.

Newsletter