Doctors: BMI charts are just a rule of thumb

Some say measurements unfairly peg people as overweight, obese

A body mass index chart divide a a person’s body weight by the square of his or her height.
A body mass index chart divide a a person’s body weight by the square of his or her height.

Body mass index charts have provoked considerable controversy in recent months because some say the BMI measurements unfairly peg people as overweight or obese.

The issue heated up on the national stage in February when the parents of a 10-year-old, 94-pound boy in Massachusetts became outraged about the “fat letter” labeling their son obese that the school district sent home.

With the blessings of the state’s public health department, for three years Massachusetts schools have taken the measurements and mailed parents letters that say whether their children are overweight, underweight, or in-between.

“Honestly, I laughed,” Tracy Watson, the mother of Cameron, reportedly said. And why not? Cameron is a member of the North Andover Boosters Club wrestling team, he is involved in martial arts, and plays football. Earlier this month, he won his state wrestling championship.

The BMI debate is the ideal occasion to gain better understanding of the tool, which has been described as imperfect. A person’s body mass index is obtained using a specific formula developed in the 19th century by Belgian statistician Adolphe Quetelet. To obtain a BMI, most people use a chart, which can be found on the Internet or in most doctor’s offices. They divide a a person’s body weight by the square of his or her height.

Dr. Colleen Olson, pediatrician at the Mercy Family Physicians and Pediatrics in Maumee and Perrysburg, takes the sting out of the controversy.

“We need a means by which to measure obesity, and BMI is a screening tool, it is not a diagnostic tool. It’s an important tool. It measures body fatness, but it’s not a direct measure [and] can correlate with the direct measures we use,” she said.

A BMI reading tells whether a doctor should look further into a person’s, health. A physical exam, review of family history, dietary patterns, and activity habits reveal the bigger picture.

“BMI identifies possible weight problems,” Dr. Olson said. “It also will tell whether a kid is underweight.

Some parents are happy with the information and others are not, she said. When families get letters from schools about their children’s BMI, she sees it as a public service.

“I think they need to view it as a community or school that’s looking out for the health of their citizens,” she said. “We do need come up with a solution to point people in the right direction. Parents should realize that this is one tool and if the doctor does other screen labs and those come back normal, then [the child] can continue living the way he’s living.”

Dr. Matthew Fourman, bariatric surgeon and medical director of the Mercy Weight Management Center in Sunforest Court, agrees that the BMI chart is imperfect, and here’s an example why: as a body builder, movie star and former California governor Arnold Schwarzenegger had a BMI indicating that he was morbidly obese. At 6 feet tall, he had more muscle mass than fat.

“That shows it is imperfect, but most Americans don’t fall into the same category as Arnold [Schwarzenegger],” said Dr. Fourman, who sees value in the charts. He said adults with a higher body mass index are at risk for certain diseases. Moreover, the surgeon said that someone with a BMI of 35 can qualify for bariatric surgery. “Patients who have an increase in BMI, even 5 points, have a 30 percent increase in higher risk of death.”

Some believe they would look sickly if they maintained their weight in accordance with BMI charts.

“I think there is a gray zone between what we consider normal weight BMI and obesity,” Dr. Fourman said, adding that most Americans’ BMI should be from 25 to 29.9. “Over 30 is more of a concern. Over 35 is where we see increases in other health problems.”

Though he said it’s a good goal to have a BMI below 30, he emphasized the importance of proper diet and exercise, and said, “Don’t worry as much about what your BMI is.”

So if BMI charts have been around so long, why is the general public only hearing about them in recent years?

“Because of the obesity epidemic,” Dr. Fourman said. “Nobody cared about their BMI until we started having issues with the obesity problem. So obesity in general is much more recognized and it’s directly linked with the obesity epidemic we have in the United States of America.”

Contact Rose Russell at or 419-724-6178.