
What Is Hard About a Clinical Diagnosis of Obesity?
It is fascinating to watch the public discourse about newly proposed criteria from the Lancet Commission for a clinical diagnosis of obesity unfold. The headline is easy. “It’s time to move beyond BMI alone.” The response to that idea has been clear and unmistakable: “What took so long?”
But then comes the hard part that stirs up strong feelings. For the sake of simplicity, we will split the issues into two major questions:
1. Why do we need this?
2. Why are there only 13-18 criteria for the clinical diagnosis?
“My System Is Better”
Make no mistake. There are other frameworks and they are good. The top three that come to mind are the Edmonton Obesity Staging System, the Canadian Obesity Clinical Practice Guideline, and the recent EASO Framework for diagnosis, staging, and management of obesity. Every one of these are good frameworks and the authors of each of them have good reason to be proud of their work.
It’s also worth noting that all of them are broadly consistent with two major premises of the Lancet Commission:
1. Diagnosis of obesity requires more than BMI.
2. Obesity can be present before symptoms other than excess adiposity appear.
These two ideas are present in all of these frameworks, but each of them deals with these issues in slightly different ways. Both the common threads and the diversity of thinking about this subject are good.
Preclinical Obesity
In the Lancet framework, if a person has excess adiposity, but meets none of the 13-18 criteria for a diagnosis of clinical obesity, they have preclinical obesity. People are expressing concerns about those 13-18 criteria in many ways. But the concerns boil down to three.
1. This is too confusing!
When all is said and done, it was easy (maybe even lazy) to simply rely on BMI to draw lines between healthy weight, overweight, and obesity. But that doesn’t make it right. Nonetheless, the easy-peasy approach of sizing people up and admonishing them to lose weight is something that people are not giving up without whining.
2. Won’t this category of preclinical obesity deny people access to care?
Two answers are possible for this concern. One is to summon a worried face and agree this is a valid concern. It certainly is.
But the other response is to reflect on the fact that 90% of people living with obesity already get denied access to care – in part because the diagnosis is too vague and lacking in rigor. So it is hard to imagine that this will make the problem perceptibly worse. In fact, it might clear up some confusion.
3. Why is name-a-criterion not on the list of clinical criteria for diagnosis?
This is the toughest question. People quite naturally ask, for instance, why doesn’t excess adiposity with type 2 diabetes but without any lipid abnormalities qualify for a diagnosis of clinical obesity? (Hint: if T2D is the primary diagnosis, treating the excess adiposity is already indicated. Duh.)
But the truth is that over time, consensus will likely emerge for other criteria to make the list. The refinement of diagnostic criteria over time is perfectly normal.
Chill and Enjoy
In closing, it makes sense for everyone tuning into this conversation to take a deep breath and enjoy the diversity of opinions.
We should also take care to avoid misrepresentations about the Lancet report. For instance, some have suggested it says clinicians should not treat excess adiposity until someone develops complications. It says no such thing. Rather, it says: “Some individuals with preclinical obesity should also have access to appropriate treatment.”
Most of all, we should celebrate the hard work that went into forging a consensus among 58 experts from all over the world and endorsement by 75 major organizations. That by itself is amazing.
Click here to read the report, here and here for different perspectives on it. For access to watch the global launch of the commission report, click here.
Human Miseries, painting by Paul Gauguin / Wikimedia Commons
Subscribe by email to follow the accumulating evidence and observations that shape our view of health, obesity, and policy.
January 28, 2025