Fat And Fiction

There’s a dangerous racial bias in the body mass index.

- Jessica Firger

AT 73, Kanta Patel is contending with a host of chronic health conditions. In 2004, she went for a physical and learned she had elevated cholesterol. Then, two years later, Patel’s doctor diagnosed her with hypertension. She’s also a borderline Type 2 diabetic.

One would never think Patel, who emigrated from India 50 years ago, had such serious illnesses. She appears fit: 5 feet tall, 102 pounds, with a body mass index of only 19. She has always been physically active, and she eats a vegetarian diet. But looks (and a great BMI number) can be deceiving.

An increasing amount of research shows that BMI and weight are not necessarily the main indicators of a person’s health. Additionally, what’s considered an unhealthy BMI—a number that may predict the onset of chronic diseases— is not the same across all races and ethnicities. Many who question the use of BMI in clinical settings point out that it’s a health metric that’s resulted from decades of research mostly conducted on white people.

However, regardless of family ancestry, BMI and weight are often the first numbers doctors consider, and they may not screen for heart disease and Type 2 diabetes if they are within normal range. A large study based on more than 40,000 people published in the International Journal of Obesity suggests that nearly half of the people categorized as overweight were cardio metabolically healthy, while 30 percent of people within the normal BMI range were not in great shape.

The U.S. Centers for Disease Control and Prevention and other public health authorities say a healthy BMI for adults is between 18.5 and 24.9. (An adult with a BMI between 25 and 29.9 is considered overweight, while someone with a BMI of 30 or above is classified as obese.)