New Delhi: A new report by The Lancet released Wednesday, which has the potential to alter the way obesity is seen and managed across the world, has suggested adopting measures apart from body mass index (BMI) to determine excess body fats in individuals and to define obesity.
This marks the first time that obesity has been defined as a condition that requires medical attention.
The new approach to diagnosing obesity in an individual may include waist circumference, waist-to-hip ratio, waist-to-height ratio or direct fat measurement, says the report by The Lancet Commission on Clinical Obesity, endorsed by 76 organisations and 58 experts globally.
Additionally, the commission has for the first time also recommended two new diagnostic categories of obesity based on objective measures of illness at the individual level—clinical and preclinical.
While clinical obesity should be seen and managed as a chronic disease associated with ongoing organ dysfunction due to obesity alone, preclinical obesity can be associated with a variable level of health risk, but no ongoing illness, experts have said.
As of now, the World Health Organisation (WHO) defines overweightedness and obesity in adults using BMI alone. Those with a BMI between 25 and 30 kilograms per square metre are considered overweight, while people with a BMI of more than 30 kilograms per square metre are classified as obese.
These BMI cut points are essentially based on health risk escalation beyond a certain BMI. However, over the years, the understanding of obesity has evolved following evidence suggesting that health risks in people with the same BMI may vary with ethnicity and may lead to different decisions on public health action.
For example, individuals of Asian descent are more susceptible to obesity-related health problems at lower BMI values than whites at the same BMI levels. This lower threshold considers the increased risk of non-communicable diseases such as type 2 diabetes and cardiovascular disease among Asians.
A statement by The Lancet Commission says that the proposal is designed to address limitations in the traditional definition and diagnosis of obesity that hinder clinical practice and healthcare policies, resulting in individuals with obesity not receiving the care they need.
“By providing a medically coherent framework for disease diagnosis, the Commission also aims to settle the ongoing dispute around the idea of obesity as a disease, which has been at the centre of one of the most controversial and polarising debates in modern medicine,” it added.
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Global epidemic
According to the WHO, in 2022, 2.5 billion adults aged 18 years and older—or 43 percent of adults globally—were overweight, including over 890 million or 16 percent of adults who were living with obesity, a condition fuelled by easy accessibility to high-calorie and refined food, sedentary lifestyles, and lack of physical activity.
In comparison, in 1990, 25 percent of adults were overweight, and of those, less than eight percent were obese.
Moreover, the global epidemic of obesity is not limited to adults alone. In 2022, an estimated 37 million children under the age of five years, and over 390 million children and adolescents aged five to 19 years were overweight.
The WHO also notes that the prevalence of overweightedness (including obesity) among children and adolescents has risen dramatically from just eight percent in 1990 to 20 percent in 2022.
A largest-of-its-kind survey by the Indian Council of Medical Research (ICMR) and Madras Diabetes Research Foundation (MDRF), which was released in 2023, said that 254 million Indians or 28.6 percent of the population had generalised obesity.
This survey put the number of people with abdominal obesity at 351 million or 39.5 percent of the population.
Over the past decades, evidence linking high BMI contributing considerably to a number of non-communicable diseases including hypertension, diabetes, dyslipidaemia (abnormal levels of lipids or lipoproteins in blood), cancers and all causes of death has been gathering.
Calling the new report a useful document in shaping the approach and attitude towards obesity, experts said it will have impacts lasting a long time.
“By stratifying people with obesity into categories and defining which specific group needs medical intervention and which may not need it yet, this document and the clinical guidelines that now emerge from it will help physicians worldwide,” Dr Ambrish Mithal, chairman and head, endocrinology and diabetes with Max Healthcare, told ThePrint.
One direct result of the new report, for instance, according to Mithal, could be to guide physicians on in which cases anti-obesity medicines should be considered.
‘Current approaches ineffective’
There is an ongoing debate among clinicians and policymakers over the current diagnostic approach to obesity, which is prone to misclassification of excess body fat and misdiagnosis of disease.
Part of the issue, the experts say, is due to obesity being currently defined by BMI, with a BMI of over 30 kilograms per square metre considered as an indicator of obesity for people of European descent.
Different, country-specific BMI cut-offs are also used to account for ethnic variability of obesity-related risk. Indian guidelines, for example, consider those with a BMI of 23 kilograms per square metre and above as overweight, and those with a BMI of 25 kilograms per square metre and above as obese.
Although BMI is useful for identifying individuals at increased risk of health issues, the commission highlights that it is not a direct measure of fat, does not reflect its distribution around the body, and does not provide information about health and illness at the individual level.
“Relying on BMI alone to diagnose obesity is problematic as some people 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,” Robert Eckel from the University of Colorado, US and a senior member of the commission, said in a statement.
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 said.
In a statement, Commission chair Francesco Rubino of King’s College London said that the question of whether obesity is a disease is flawed because it presumes an implausible all-or-nothing scenario where obesity is either always a disease or never a disease.
“Evidence, however, shows a more nuanced reality. Some individuals with obesity can maintain normal organ function and overall health, even long term, whereas others display signs and symptoms of severe illness here and now,” he added.
Beyond BMI
Whilst recognising BMI as useful as a screening tool to identify people who are potentially living with obesity, commission experts have recommended confirmation of excess fat mass and its distribution around the body using methods such as at least one measurement of body size—waist circumference, waist-to-hip ratio or waist-to-height ratio—in addition to BMI.
The other option for clinicians, according to the report, is considering at least two measurements of body size—waist circumference, waist-to-hip ratio or waist-to-height ratio regardless of BMI, in addition to direct body fat measurement such as by a bone densitometry scan or DEXA regardless of BMI.
In people with very high BMI such as 40 kilograms per square metre or more, excess body fat, however, can be pragmatically assumed, says the report.
The commission also provides a new model for disease diagnosis in obesity based on objective measures of illness at the individual level.
Clinical obesity has been defined as a condition of obesity associated with objective signs and/or symptoms of reduced organ function, or significantly reduced ability to conduct standard day-to-day activities, such as bathing, dressing, eating and continence, directly due to excess body fat.
People with clinical obesity should be considered as having an ongoing chronic disease and receive appropriate management and treatments. The commission sets out 18 diagnostic criteria for clinical obesity in adults and 13 specific criteria for children and adolescents such as breathlessness, obesity-induced heart failure, knee or hip pain, with joint stiffness and reduced range of motion as a direct effect of excess body fat on the joints.
The other criteria include certain alterations of bones and joints in children and adolescents limiting movement, other signs and symptoms caused by dysfunction of other organs including kidneys, upper airways, metabolic organs, nervous, urinary and reproductive systems and the lymph system in the lower limbs.
The latest report says that the reframing of obesity is designed to ensure that all people living with obesity receive appropriate health advice and evidence-based care when needed, with different strategies for clinical and preclinical obesity.
“People with clinical obesity should receive timely, evidence-based treatment, with the aim to fully regain or improve the body functions reduced by excess body fat, rather than solely to lose weight. The type of treatment and management for clinical obesity—lifestyle, medication, surgery, etc—should be informed by individual risk: benefit assessments and determined by an active discussion with the patient,” it stresses.
Preclinical obesity, on the other hand, has been classified as a condition of obesity with normal organ function.
And while people living with preclinical obesity, therefore, do not have ongoing illness, they have a variable but generally increased risk of developing clinical obesity and other conditions in the future, including type 2 diabetes, cardiovascular disease, certain types of cancer and mental illness, among others, the report emphasises.
Such people, according to the experts, therefore should be supported to reduce the risk of potential disease.
(Edited by Radifah Kabir)
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