Deep Analysis: What is Class 3 Obesity? From "Morbid Obesity" to the Evolutionary Path of Personalized Medical Diagnosis

In recent years, the global obesity population has risen sharply, with obesity and its related diseases becoming a global public health issue. In the diagnosis and treatment of obesity, the medical community has been continuously exploring and improving methods to provide more precise and effective medical services. Recently, a global committee report published in The Lancet's sub-journal Lancet Diabetes & Endocrinology, proposing major reforms to obesity diagnosis, has attracted widespread attention. This report, endorsed by 76 medical institutions globally, advocates expanding obesity diagnostic standards from a single body mass index BMI to a more comprehensive indicator system, including body fat content, organ health status, and daily activity capabilities, aiming to provide more personalized diagnostic and treatment plans for patients.

Class 3 Obesity: A Concept Urgently Awaiting Redefinition

• For instance, an athlete with high muscle mass might have a high BMI but be extremely healthy. Conversely, some individuals with normal BMI might have excessive visceral fat, increasing their risk of serious diseases like heart disease.
• These diagnostic limitations mean some patients cannot receive timely and effective treatment. For example, some insurance companies require evidence of obesity-related diseases such as type 2 diabetes before covering obesity treatment, overlooking obesity itself as an independent chronic disease.

From "Morbid Obesity" to "Clinical Obesity": An Effort to Destigmatize

The term "morbid obesity" originated in 1963, initially intended to provide insurance coverage for intestinal bypass surgery for patients with a BMI over 40.

• However, the word "morbid" carries negative connotations beyond its medical meaning, creating uncomfortable associations in everyday life. This led to public stigmatization, suggesting obese individuals lack weight loss willpower.

To eliminate this stigma, medical organizations like the World Health Organization WHO began replacing "morbid obesity" with "class 3 obesity".

The Lancet committee's report went further, introducing the concept of "clinical obesity" to more accurately describe obesity's impact on individual health. Clinical obesity refers to obesity associated with objective organ function decline or significant reduction in daily activity capabilities, directly caused by excessive body fat.

The committee established 18 diagnostic criteria for adult clinical obesity and 13 for childhood and adolescent clinical obesity, including:

• Breathing difficulties caused by obesity's impact on lungs
• Obesity-induced heart failure
• Knee or hip joint pain due to excessive body fat, accompanied by joint stiffness and reduced mobility
• Certain skeletal and joint changes in children and adolescents that limit movement
• Other signs and symptoms caused by dysfunction in kidney, upper respiratory tract, metabolic organs, nervous system, urinary and reproductive systems, and lower limb lymphatic systems

The introduction of the "clinical obesity" concept helps doctors differentiate between health and disease at the individual level, enabling more precise and personalized treatment plans. For instance, for clinical obesity patients with organ function decline, the treatment goal should be completely restoring or improving body functions affected by excessive body fat, rather than simply reducing weight.

From BMI to Multi-Indicator System: Advancing Precise Obesity Diagnosis

The Lancet committee's report recommends adopting a multi-indicator system for obesity diagnosis, rather than relying solely on BMI. They suggest using one of the following methods to confirm excess body fat and its distribution:

• In addition to BMI, measure at least one body dimension waist circumference,waist−hipratio,orwaist−heightratio
• Measure at least two body dimensions, regardless of BMI
• Directly measure body fat such as through bonedensity scanning or DEXA
• For individuals with very high BMI e.g.,>40kg/m2, assume excess body fat

This multi-indicator diagnostic approach can more comprehensively assess patient health, avoiding potential misdiagnosis and missed diagnosis that might occur when relying solely on BMI.

Furthermore, the report introduced the concept of "pre-clinical obesity," which describes an obesity state characterized by excess body fat while maintaining normal organ function.

Although pre-clinical obesity patients do not currently present with active diseases, they face a significantly elevated risk of developing clinical obesity and other non-communicable diseases, including type 2 diabetes, cardiovascular diseases, certain cancer types, and mental health disorders. Therefore, proactive medical support and interventions should be provided to mitigate the potential progression of these health risks.

New Diagnostic Standards: Transformations in Drug Development and Medical Insurance

The new diagnostic standards proposed by the Lancet committee will have profound implications not only for clinical obesity diagnosis and treatment but also for drug development and medical insurance.

For example, new weight loss medications like Novo Nordisk's Wegovy and Eli Lilly's Mounjaro are approved in the United States for individuals with a BMI ≥30 or BMI ≥27 with weight-related conditions such as hypertension or sleep apnea.

Under the new diagnostic standards, some patients previously considered obese may no longer qualify for these medications, which will impact the weight loss drug market.

On the other hand, pharmaceutical companies are increasingly recognizing the importance of body composition and are developing drugs that help people reduce fat while maintaining muscle mass. This will drive weight loss medications towards improving body composition and health status, rather than simply reducing weight.

In the medical insurance realm, implementing the new diagnostic standards will bring both challenges and opportunities. Insurance companies will need to develop policies based on the new standards to ensure clinical obesity patients receive necessary medical coverage.

Conclusion: A Revolution in Health Understanding

The Lancet committee's new obesity diagnostic standards represent a milestone initiative, moving obesity diagnosis and treatment from a one-size-fits-all approach to a more precise, personalized direction.

This transformation will impact not only the medical field but also societal perceptions of obesity, support for obese individuals, and the development of related industries.

As these new diagnostic standards are promoted and applied, obesity prevention and treatment will become more scientific and effective, benefiting more patients and ultimately achieving the grand goal of improving public health.