The Lancet Diabetes & Endocrinology Commission, a group of 58 leading experts from various medical specialties and countries, on Tuesday proposed a new approach to defining and diagnosing obesity. This approach goes beyond just using Body Mass Index (BMI)—a numerical estimate of a person’s weight relative to their height, traditionally used to determine obesity.
The commission acknowledges that BMI is a helpful screening tool for identifying people who might have obesity but experts suggest it shouldn’t be the sole method. Instead, they recommend confirming obesity by assessing excess body fat and how it’s distributed in the body. This includes combining BMI with at least one body size measurement, such as waist circumference, waist-to-hip ratio, or waist-to-height ratio, or using at least two body size measurements regardless of BMI.
The commission also suggests direct body fat assessments, like DEXA scans, for a more accurate measurement, especially when BMI is not used. For people with an extremely high BMI (for instance above 40 kg/m²), it can be assumed they have excess body fat without additional testing, the commission has recommended.
“Moving beyond BMI-only approaches helps prevent under and over diagnosis of obesity-related health risks. These new frameworks enable more precise, personalized treatment strategies that consider individual metabolic profiles and risk factors,” Dr Anoop Misra, Chairman, National Diabetes, Obesity and Cholesterol Foundation and one of the Commission authors told The Indian Express. “Excess fat is linked to both metabolic and mechanical health issues. Implementing a revised classification system that distinguishes stages of obesity can enhance the efficacy of interventions,” he said.
Why has the commission recommended a newer approach
A BMI of over 30 Kg/m2 is considered as an indicator of obesity for people of European descent. However, different, country-specific BMI cutoffs are also used to account for ethnic variability of obesity-related risk. “Relying on BMI alone to diagnose obesity is problematic,” Commissioner Professor Robert Eckel, University of Colorado Anschutz Medical Campus (USA) said.
“Some individuals tend to store excess fat at the waist or in and around their organs, such as the liver, the heart or the muscles, and this is associated with a higher health risk compared to when excess fat is stored just beneath the skin in the arms, legs or in other body areas. But people with excess body fat do not always have a BMI that indicates they are living with obesity, meaning their health problems can go unnoticed. Additionally, some people have a high BMI and high body fat but maintain normal organ and body functions, with no signs or symptoms of ongoing illness,” Eckel explains.
Two new categories of obesity: ‘clinical obesity’ and ‘pre-clinical obesity’
The Commission has also introduced two new diagnostic categories of obesity — clinical and preclinical obesity — to enable clinicians to differentiate between health and illness at the individual level.
The commission defines clinical obesity as a chronic, systemic illness characterized by alterations in the function of tissues, organs or the individual, due to excessive and or abnormal fat in the body. It outlines 18 diagnostic criteria for clinical obesity in adults, focussing on the central nervous system, respiratory system, cardiovascular health, metabolism, liver, kidneys, and reproductive health. Additionally, it specifies 13 diagnostic criteria applicable to both children and adolescents.
The commission defines pre-clinical obesity as a condition where there is excess body fat but the tissues and organs are still functioning normally. However, it increases the risk of developing clinical obesity and other serious health problems, such as type 2 diabetes, heart disease, certain cancers, and mental health issues.
According to Dr Misra, for preclinical obesity, lifestyle modifications such as diet and exercise can often suffice. “For clinical obesity, additional therapies, including medications and, in some cases, weight-loss surgery, may be necessary. This approach allows for tailored interventions, improving outcomes while addressing India’s unique health challenges related to abdominal obesity and its complications,” Misra said.
Why prioritising abdominal obesity is crucial for India
Indians have a high prevalence of abdominal obesity and related diseases, such as diabetes, even at slightly elevated body weight and waist circumference, Dr Misra emphasizes. “Given this context, focussing on abdominal obesity as a priority is both rational and relevant for controlling associated diseases. Equally important is fat accumulation in the liver, known as fatty liver, which is broadly a part of abdominal fat accumulation. This condition is another critical component of the metabolic cluster seen in Indians and is linked to diabetes and heart disease.”
According to the National Family Health Survey (NFHS-5, 2019–21), 6.4% of women and 4.0% of men aged 15–49 years are obese. Recent research highlights that Asian Indians experience more severe metabolic consequences from excess fat accumulation. “Studies show that excess fat in Indian populations generates higher levels of inflammation and metabolic disturbance at lower BMI thresholds compared to Western populations. Additionally, childhood obesity rates are rising across the country, leading to concurrent increases in conditions such as diabetes, lipid disorders, fatty liver disease, and cardiovascular disease,” Dr Misra explains.
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