When the number on the scale can no longer define “fat people”, the intervention for obesity will also become more scientific. In January 2025, a significant report published in The Lancet Diabetes & Endocrinology completely overturned the obesity diagnosis system that had persisted for decades. This new standard, jointly developed by 58 experts worldwide and supported by 75 medical organizations, marks a revolutionary shift in obesity diagnosis from “looking at the weight number” to “looking at the harm of fat”, and is regarded as the most milestone breakthrough in the field of obesity since the advent of BMI.
The “Three Blind Spots” of the Traditional BMI standard
BMI (Body Mass Index), as a core indicator for diagnosing obesity, has been in use for decades. It is calculated by dividing weight (in kilograms) by the square of height (in meters). According to the “Guidelines for the Diagnosis and Treatment of Obesity (2024 Edition)” released by the National Health Commission of the People’s Republic of China, a BMI of 24 but below 28 is considered overweight, while a BMI of 28 or above is considered obese. However, this seemingly objective standard has three fatal blind spots:
1.1 The “Number Trap” That Fails to Distinguish between Fat and Muscle
The essence of BMI is the ratio of weight to height, and it cannot distinguish whether the weight comes from fat or muscle. This leads to fitness enthusiasts, athletes and other people with high muscle mass being misjudged as obese due to an excessive BMI, while some people with a high body fat percentage but normal weight are considered healthy. Studies show that about 15% of the normal BMI population have an excessive fat percentage. These people have a 2 to 3 times higher risk of developing diabetes and cardiovascular diseases than those with normal body fat.
1.2 Ignoring the “Health Risks” of Fat Distribution Differences
BMI cannot reflect the distribution of fat in the body, but the impact of fat distribution on health is far greater than the total amount of fat. People with an apple-shaped figure (abdominal obesity) have visceral fat accumulation that directly affects the functions of important organs such as the liver and pancreas. Their risk of developing diabetes and cardiovascular diseases is 3 to 5 times higher than that of people with a pear-shaped figure (buttock obesity). However, people of these two body types may have the same BMI value.
1.3 “One-size-fits-all” approach without considering an individual’s health status
BMI is a population-level epidemiological indicator, but its accuracy is insufficient when used for individual health assessment. Research has found that approximately 20% of individuals with a BMI exceeding the standard have completely normal metabolic indicators, while about 15% of those with a normal BMI have metabolic problems such as insulin resistance and hyperlipidemia. This phenomenon of “healthy overweight people” and “metabolically abnormal thin people” directly challenges the rationality of BMI as the sole criterion for diagnosing obesity.
2. New Standard: A paradigm Shift from “Digital Obesity” to “Healthy Obesity”
The new standard published by The Lancet defines obesity as “excessive fat accumulation accompanied by an increased risk of health damage”, with the core shift from “being overweight” to “impaired function”, and from “a single indicator” to “multi-dimensional assessment”. This transformation is known as a “paradigm shift” in the field of obesity diagnosis.
2.1 Three-dimensional Diagnostic Framework: Redefining the Core Elements of Obesity
The new standard has established a three-dimensional diagnostic framework of “body fat indicators – health status – individualized assessment” :
Body fat indicators: By comprehensively considering indicators such as waist circumference, waist-to-hip ratio, and waist-to-height ratio, it more accurately reflects the content and distribution of body fat. For the Asian population, men with a waist circumference greater than 90cm, a waist-to-hip ratio greater than 0.90, and a waist-to-height ratio greater than 0.50; A female with a waist circumference greater than 80cm, a waist-to-hip ratio greater than 0.85, and a waist-to-height ratio greater than 0.50 can be diagnosed as obese.
Health status: Assess whether there is organ damage or functional disorder caused by obesity, such as hypertension, diabetes, joint pain, decreased mobility, etc.
Individualized assessment: By comprehensively considering factors such as age, gender, race, family medical history, and lifestyle, personalized diagnostic criteria are formulated.
2.2 Two-stage classification: Precise intervention from “subclinical” to “clinical”
The new standard divides obesity into two stages for the first time, corresponding to different intervention strategies:
Subclinical obesity: Excessive accumulation of fat without causing organ damage or restricted movement. Although this group of people have no obvious symptoms, their risk of chronic diseases is significantly increased. The focus of intervention is to prevent disease progression through lifestyle adjustments.
Clinical obesity: Fat accumulation has led to disease or functional impairment, and systematic treatment as a chronic disease is required, including lifestyle adjustments, drug therapy, and even surgical treatment.
This classification method is similar to the staging system of “prediabetes”, suggesting that obesity should indeed be regarded as a disease rather than a body shape issue. As Dr. Jennifer Hwang of the University of Chicago said, “Under the new standard, obesity is no longer just a number or body type, but a reflection of health and function.”
2.3 Diversified Diagnostic Tools: From “Indirect Speculation” to “Direct Measurement”
The new standard recommends the use of multiple methods for directly measuring body fat to improve diagnostic accuracy:
Imaging methods such as dual-energy X-ray absorptiometry (DEXA), computed tomography (CT), and magnetic resonance imaging (MRI) can precisely measure body fat content and distribution.
Bioelectrical impedance method: It estimates body fat percentage by measuring the electrical impedance of the human body. It is simple to operate and suitable for large-scale screening.
Body shape measurement: waist circumference, waist-to-hip ratio, waist-to-height ratio, etc., can indirectly reflect the accumulation of abdominal fat.
For high-risk individuals with a BMI over 40kg/m², it can be reasonably assumed that there is excessive fat in their bodies, and there is no need to measure body fat separately.
3. The “Three Major Changes” Brought by the New Standards
3.1 Obesity rate “soaring” : More people will receive timely intervention
The latest research in the United States shows that, based on the traditional BMI standard, the obesity rate among adults is approximately 40%. However, according to the new standards, the obesity rate has soared directly to 75%, equivalent to an additional 46 million “new obese people”. Among them:
For the traditionally obese population (BMI≥30) : The obesity rate is 100% under the new standard
Traditional overweight population (BMI 25-30) : The obesity rate under the new standard is 80.4%
The obesity rate of the traditional normal BMI population (BMI<25) under the new standard is 38.5%
This data indicates that a large number of people with a normal BMI but excessive body fat or metabolic problems will receive timely intervention under the new standard. For the Asian population, as their body fat content is generally higher than that of the Western population, the obesity rate under the new standard may be even higher.
3.2 Shift in Treatment Strategy: From “Weight Loss” to “Health Restoration”
Under the new standards, the goal of obesity treatment is no longer merely to lose weight, but to restore the body’s functions that have been damaged due to excessive body fat.
Subclinical obesity: The focus is on lifestyle interventions such as dietary adjustments, increased physical activity, and improved sleep to reduce the risk of chronic diseases. It is recommended to adopt healthy dietary patterns such as the Mediterranean diet and the DASH diet, and engage in at least 150 minutes of moderate-intensity aerobic exercise every week.
Clinical obesity: It requires a comprehensive approach of lifestyle adjustments, drug treatment, and even surgical treatment. For patients with insulin resistance, drugs such as GLP-1 receptor agonists can be used; For severely obese patients, bariatric surgery can be considered.
This stratified treatment strategy can make more effective use of medical resources and improve treatment outcomes. Studies show that early intervention for subclinical obese individuals can reduce the risk of diabetes and cardiovascular diseases by 30-50%.
3. Reconstruction of Public Health System: From “Passive Response” to “Active Prevention”
The implementation of the new standards will have a profound impact on the public health system:
Adjustment of medical insurance policies: It is necessary to re-evaluate the medical insurance access standards for obesity treatment and include more effective treatment methods in the medical insurance coverage.
Optimization of physical examination items: Measurements such as waist circumference and body fat percentage should be incorporated into routine physical examination items to enhance the early screening rate for obesity.
Health education upgrade: It is necessary to popularize the concept of “healthy obesity”, enhance public awareness of the harm of excessive body fat, and advocate a healthy lifestyle.
Medical resource allocation: It is necessary to increase the investment in medical resources for obesity diagnosis and treatment, including professional doctor training, drug research and development, and the construction of bariatric surgery centers, etc.
Conclusion: Redefining obesity means redefining health
Professor Rubino, chair of the Lancet Obesity Commission, pointed out: “The actual situation of obesity is very complex. Some obese people can maintain good health for a long time, while others show severe disease symptoms. We should adopt more personalized diagnostic and treatment strategies to deal with the long-term risks of obesity.”
The introduction of the new standard marks the shift of obesity diagnosis from a “number game” to a “health assessment”, and from a “one-size-fits-all” approach to an “individualized” one. This is not only a change in diagnostic criteria, but also an innovation in health concepts – true health is not about the number on the scale, but about the normal operation of body functions and the continuous improvement of the quality of life. For everyone, paying attention to body fat distribution and attaching importance to metabolic health are the keys to staying away from obesity-related diseases.
As Dr. Jennifer Hwang said, “When doctors, policymakers and the general public all start to understand obesity in terms of ‘functional health’ rather than ‘physical health’, perhaps we are truly beginning to understand obesity – redefining obesity is actually redefining health.”
Post time: Feb-02-2026