Everyone seems to think they know obesity when they see it. In the popular imagination this is easy. But it turns out that thinking it’s easy makes diagnosing obesity hard. BMI was the old, seemingly easy way for an objective diagnosis. Is the number over 30? Then the diagnosis was obesity. Under 30? Nope.

Now, though, the one thing people agree upon is that BMI all by itself is inadequate to establish the diagnosis of obesity. Where the agreement ends is when the conversation turns to an alternative approach. In Nature Communications Medicine,  Javier Gómez-Ambrosi and colleagues offer a critical appraisal of competing frameworks for diagnosis.

Three Contrasting Views

Arya Sharma, Lisa Schaffer, Francesco Rubino, and Luca Busetto at the Canadian Obesity Summit, photo by Steven Teoh

At the Canadian Obesity Summit yesterday, three distinguished clinicians – Arya Sharma, Luca Busetto, and Francesco Rubino – explained their frameworks and how they differ. Sharma covered Obesity Canada’s definition. Busetto gave a view of the EASO framework. Rubino explained what the Lancet Commission does and does not say about diagnosing clinical obesity.

Did they resolve any differences? Not really. And it’s not clear that those differences matter. Because the practical reality is that systems for delivering obesity care are still very much driven by BMI. And payers are mostly looking for ways to limit access to care. Psychologist, dietitian, and OAC board member Nina Crowley summed it up well:

“This is one of those moments that reinforces a hard truth in obesity care: you’re not going to make everyone happy. And maybe that’s not the goal. When science, lived experience, policy, and industry all intersect, tension is inevitable. The challenge is not eliminating disagreement, but navigating it without losing sight of patient-centered care.”

A Critical Appraisal

In their critical appraisal, Gómez-Ambrosi and colleagues tell us that none of these frameworks are ideal:

“Some definitions may misclassify individuals with increased cardiometabolic risk. Notably, many people labelled as having ‘preclinical obesity’ under the Lancet Commission criteria showed increased metabolic risk factors when assessed using the EASO framework. These findings suggest that obesity classification systems may differ in how well they detect individuals at risk and that more consistent approaches are needed to guide decision making.”

How Hard Is It Really?

Honestly, we find mostly frustration in this debate – if it even is a debate. What should center this conversation is shared decision making with each and every patient. Do they have medical, functional, social, or psychological issues related to adiposity? What can health professionals offer to help them live longer, feel better, and do more?

Those two questions are really all we need to ask. Everything else in this debate seems very unhelpful.

Click here for the new paper by Gómez-Ambrosi et al and here for further perspective.

Conversation Puzzle, painting by Edward Wadsworth / WikiArt