0708-Feature-Diagnosing obesity_Blog

Measuring body mass index may not be enough to diagnose obesity in some minority groups, according to a new statement published this week by the American Heart Association. The size of a person’s waist can also play a key role in making the diagnosis.

“BMI doesn’t tell the whole story,” said Goutham Rao, M.D., the statement’s lead author and vice chair of the department of family medicine at NorthShore University Health System and the University of Chicago. “One has to look at a broader picture to figure out if an individual is obese and is at high risk for heart disease.”

Relying solely on BMI, a ratio of weight to height, could mean obesity diagnoses are missed and treatments are never started. Under current AHA guidelines, adults with a BMI of 30 or higher are considered obese and need treatment.

Non-Hispanic blacks, Latinos and Asian-Americans are at greater risk for cardiovascular diseases. For example, many Asian-Americans are “metabolically obese” and suffer from obesity-related diseases even though their BMIs are in the normal or overweight range, Rao said.

The new statement recommends that adults of any race or ethnicity have both their waist circumference and BMI measured each year. Waist circumference measures visceral fat, which wraps around the internal organs.

Measuring a person’s waist will hopefully become as common as stepping on a scale, Rao said.

Women with a waist size greater than 35 inches and men with a waist larger than 40 inches are at higher risk for heart disease and Type 2 diabetes, according to the National Heart, Lung, and Blood Institute.

That’s even for people who fall into the normal-weight BMI category, Rao said.

The statement also recommends an overall risk assessment to predict a person’s long-term risk of heart attack or stroke.

“We need to think beyond BMI and increase awareness of the importance of waist circumference for the public and healthcare providers,” said Laura L. Hayman, Ph.D., associate vice provost for research and professor of nursing at the University of Massachusetts Boston who wrote a commentary about the statement.

“One size does not fit all,” she said. “The same cut[off] points don’t apply equally well to predicting disease in all populations. BMI alone, even with lower thresholds, is useful but not ideal.”