by Richard Weil, M.Ed., CDE
Founder and Director
Transformation Weight Control
In January of this year a 42-page article titled, “Definition and diagnostic criteria of clinical obesity” was published by Rubino and colleagues in a leading medical journal called The Lancet. Over a period of two years, 58 obesity experts met monthly to 1) redefine obesity, 2) to describe the limitations of body mass index (BMI), and 3) discuss whether obesity is a disease.
In a nutshell, here’s what they came up with:
- First a definition: Body mass index is the ratio between your weight and your height. It has historically been used to 1) predict good health, 2) estimate percent of body fat, 3) determine the distribution of body fat (higher in the abdomen, or from the hips down), and 4) classify individuals into underweight, healthy weight, overweight, and obesity categories. It turns out it’s not very good at any of these, but no one in the medical or research fields disputes this. In fact, it’s old news; the limitations of BMI have been discussed for decades. A simple example. A professional athlete who is 5 feet 9 inches and weighs 210 pounds, but is solid muscle with less than 8% body fat, would be classified as obese. Obviously, this athlete does not have obesity. Another example is what’s known as the obesity paradox. That is, individuals with BMIs in the obese category may have normal blood pressure, blood glucose (sugar), total cholesterol, LDL (the bad fat), and triglycerides (97% of the fat we eat). I conducted an analysis of individuals in our program and 62% of them, with an average BMI of 43.1 (78 pounds into the obesity category), had normal levels of these biomarkers.
The experts suggest that instead of BMI, a more accurate method for measuring body fat to determine whether a person has obesity and health risk is to measure waist circumference, waist-to-hip ratio, or waist-to-height ratio. Obesity and health risk is defined as a waist circumference of 40 inches or higher for men and 35 inches or higher for women; a waist-to-hip ratio of more than 0.9 for men and more than 0.85 for women; and a waist-to-height ratio of more than 0.5. A DEXA scan may also be used to measure excess body fat. A DEXA scan requires a physician’s prescription and involves radiation exposure. Click HERE for a description of waist-to-hip ratio.
- The authors argue that obesity is not a disease. My take on it is they are wrong. First, read my blog: “Is Obesity a Disease. You bet!” Ironically, in their own words, the authors define disease as “A distinct pathophysiology that can cause alterations of either a single organ or multiple organs (systemic diseases)”. And if you look up disease in Webster’s dictionary, you’ll find: “A disorder of structure or function in a human, animal, or plant, especially one that has a known cause and a distinctive group of symptoms, signs, or anatomical changes.” If having obesity doesn’t fit these criteria, then I don’t know what does. Plus, as you’ll see in my blog that I reference above, the American Medical Association, the World Health Organization, the National Institutes of Health, The Obesity Society, the American Heart Association, the Obesity Medicine Association, and the American Society for Metabolic and Bariatric Surgery, all consider obesity as a disease. That’s a pretty illustrious group of organizations that consider obesity a disease.
The most compelling evidence for obesity as a disease is written by Mathias Bluher in Nature Reviews|Endocrinology in 2019. He states, “The key rationale for defining obesity as a disease (in addition to the health risks directly attributable to excess body weight) is the distinct pathophysiology in people with obesity resulting in powerful homeostatic mechanisms that hinder weight loss and promote further weight gain.
These altered biological mechanisms in people with obesity explain why short term behavioral or medical interventions are frequently mot sufficient to result in long term weight loss.
Although attempts to promote healthy eating and more physical activity might be important for obesity prevention at the society level, these recommendations are not sufficient to reduce BMI in individuals already living with a high body weight.”
- And here’s the main point, redefining obesity. Summarizing, they broke obesity into two categories:
- Preclinical Obesity: Someone with a BMI above 25 but without complications could be categorized as having preclinical obesity, suggesting they should be monitored but may not need aggressive treatment.
- Clinical Obesity: Someone with a BMI over 40, or those with obesity-related medical conditions, would be classified as having clinical obesity and would likely require medical intervention.
They don’t intend to eliminate BMI altogether, but this is a paradigm shift in how the medical profession will evaluate and treat individuals with obesity. However, until this new approach is taught to future physicians in medical school, its implementation and efficacy in improving outcomes and reducing obesity’s burden will most likely not be embraced by the medical community.
For further reading:
https://www.healio.com/news/endocrinology/20250115/lancet-report-offers-a-new-reframing-for-defining-diagnosing-obesity
https://www.thelancet.com/journals/landia/article/PIIS2213-8587(25)00004-X/fulltext
https://transformationweightcontrol.com/is-obesity-a-disease-you-bet/
Click HERE for the complete Rubino article.
© 2025 Richard Weil, M.Ed., CDE, All Rights Reserved
