More than 18 months have passed since The Lancet Diabetes & Endocrinology Commission proposed a new framework for assessing obesity and its associated cardiovascular (CV) risks, debate over BMI continues.

The commission recommended distinguishing between preclinical obesity, in which excess adiposity increases future health risk despite the absence of obesity-related illness, and clinical obesity, in which excess adiposity has already caused illness. Making that distinction, the commission argued, requires more than BMI alone because it does not adequately capture body fat distribution or obesity-related CV risk.

One of the latest studies supporting this concept followed 102,237 adults with preclinical obesity and 182,953 adults with clinical obesity. None had diagnosed CV disease at baseline.

During approximately 12 years of follow-up, unsurprisingly, men with clinical obesity had nearly twice the rate of CV disease as men without obesity, whereas women with clinical obesity had a 2.5-fold higher rate.

Importantly, participants with preclinical obesity were also at an increased risk. Women experienced a 38% higher rate of CV disease than women without obesity, whereas men had an 18% higher rate.

Although such findings support the Commission’s proposed framework, the recommendations remain controversial.

The Lancet Commission, Endocrine Society at Odds

The commission report included 37 consensus statements addressing the clinical assessment, diagnosis, and treatment goals for obesity.

Although more than 76 organizations worldwide endorsed the recommendations, not everyone agreed.

In response, the Endocrine Society argued that moving beyond BMI in diagnosing obesity could delay treatment by introducing what it termed “rigid diagnostic thresholds.”

The Obesity Medicine Association also expressed concern that the proposed definitions could shift obesity from being viewed as a disease to being regarded as “merely a risk factor.”

Tape Measures Now, High-Tech Later

“We don’t have to get rid of BMI. We need other, much better markers of disease because BMI doesn’t measure fat,” said Robert L. Dubin, MD, associate professor at the Pennington Biomedical Research Center, Louisiana State University in Baton Rouge, Louisiana.

“Obesity is a disease of dysfunctional fat.”

Some of those additional measures, such as a simple tape measure for waist circumference, are already readily available. Others are still being refined.

For population-based studies, BMI remains an excellent tool, Dubin said. For individual patients, however, it is insufficient.

To illustrate, he pointed to the difference between a typical patient with obesity and a muscular boxer who could share the same BMI.

“That right there tells you what the problem is,” he said.

“I don’t think anyone would argue that BMI is inadequate. But everything we do in this space is based on BMI,” including eligibility for obesity medications and bariatric surgery.

Like most changes in medicine, incorporating additional adiposity measures into routine CV risk assessment will likely take time, he said.

Part of the challenge is that some technologies remain imperfect or insufficiently validated.

Although bioelectrical impedance is often used to measure body fat, Dubin said he remains cautious about its clinical utility because accuracy can be affected by dehydration and recent physical activity.

Three-dimensional body composition imaging appears more promising, he said, although additional refinement is needed. Some research suggests its accuracy still varies across population subgroups.

For now, Dubin recommends clinicians supplement BMI with waist circumference and waist to hip ratio, which he termed “a good start.”

The greatest limitation of using BMI alone, he added, is patient misclassification.

For clinicians who say they lack time for additional measurements, Dubin noted that waist circumference can be obtained quickly and incorporated into routine intake by nursing staff.

In his own practice, Dubin measures patients’ height and weight, calculates BMI, and routinely obtains waist circumference and waist to hip ratio.

Although imperfect, he sometimes also performs a bioelectrical impedance analysis.

He also evaluates patients for metabolic dysfunction-associated steatotic liver disease, occasionally ordering a liver ultrasound.

“Then you are able to come up with a fairly decent representation of who you are dealing with and how best to treat them,” he said.

BMI Still Has an Important Role

Elisabeth Kramer, MD, an internal medicine and lifestyle medicine physician with Kaiser Permanente in Gaithersburg, Maryland, also incorporates additional anthropometric measures into selected patient evaluations.

“BMI is still an important measure,” Kramer told Medscape Medical News.

“It does have benefits. But it doesn’t account for muscle mass, body composition, or where fat is stored in the body, all of which matter. Two people can have the same BMI and very different health risks.”

She tells patients that having their weight measured at office visits remains important.

Like Dubin, Kramer sees value in additional measures but notes that many are not yet readily available in routine practice.

“Some are costly, and not all the measures are available on the spot,” she said.

In her practice, all patients are weighed, and she sometimes measures waist circumference when she suspects emerging weight-related health concerns. She also monitors blood pressure, blood sugar, and other metabolic markers.

Even when BMI is not in what she considers the “danger zone,” rising blood pressure or A1c levels prompt concern.

“Then all the alarm bells go off,” she said.

At that point, she is more likely to prescribe antihypertensives and lipid-lowering medications, as clinically indicated.

“For most patients, right now, the BMI metric at least gives us some guidance,” Kramer said.

In time, as newer measures become more accurate, practical, and widely available, “I would love to include those in a daily practice more and more and more,” she said.

Kramer and Dubin reported no relevant disclosures.