With over a billion people globally affected by obesity, the Commission advocates a new approach, proposing a universal definition and diagnosis that prioritises individual health and enhances support through global healthcare systems
Published Jan 16, 2025 | 7:00 AM ⚊ Updated Jan 16, 2025 | 7:00 AM
For years, doctors have used Body Mass Index (BMI) to measure body fat and figure out health risks related to obesity.
Now, a global group of experts, supported by over 75 medical organisations and published in The Lancet Diabetes & Endocrinology, is suggesting a new and improved way to diagnose obesity.
This method looks at more than just BMI—it includes other ways to measure body fat and checks for clear signs of health problems in each person.
This approach aims to fix problems with the old way of defining and diagnosing obesity, which often left people without the care they needed.
The experts also hope their new system will help settle the heated debate about whether obesity should be considered a disease—a topic that has divided opinions in modern medicine for years.
“The question of whether obesity is a disease is misleading because it assumes an all-or-nothing answer—that obesity is either always a disease or never a disease,” said Professor Francesco Rubino from King’s College London, who leads The Lancet Commission, in a statement. “The truth is more complex. Some people with obesity can stay healthy for a long time, while others may experience serious health problems right away.”
He explained that seeing obesity only as a risk factor, and not a disease, can prevent people who are unwell due to obesity, from getting the care they urgently need. On the flip side, labelling all obesity as a disease could lead to unnecessary treatments or surgeries, which may harm individuals and place a huge financial burden on society.
With over one billion people worldwide now living with obesity, the Commission suggests a new approach. It proposes a clear, universal way to define and diagnose obesity that focuses on individual health and provides better support through healthcare systems globally.
Doctors and policymakers are debating the current way obesity is diagnosed, which often leads to mistakes in identifying excess body fat and diagnosing related health problems.
Right now, obesity is mainly defined by Body Mass Index (BMI), with a BMI over 30 considered obesity for people of European descent. Other countries use different BMI thresholds to account for variations in obesity risks among different ethnic groups.
While BMI is a helpful tool for spotting people at risk of health issues, the Commission points out its limitations. BMI doesn’t directly measure body fat, show where fat is located in the body, or provide details about a person’s overall health.
“Using BMI alone to diagnose obesity can be misleading,” explains Professor Robert Eckel, from the University of Colorado, in a statement. “Some people store fat around their waist or organs like the liver or heart, which raises health risks more than fat stored under the skin in other areas. However, these risks might not show up in their BMI, so their health problems go unnoticed. At the same time, there are people with a high BMI and high body fat who still have healthy organs and no signs of illness.”
“For many years, BMI, a simple calculation using height and weight, has been the go-to method for estimating body fat. But while it’s easy to use, BMI has some serious flaws,” said Dr. Rajeev Jayadevan, Gastroenterologist and Chairman of the Indian Medical Association Research Cell in Kerala, speaking to South First.
One major issue, he explained, is that BMI doesn’t show where fat is located. It can’t measure belly fat, muscle mass, or bone weight, and it doesn’t account for differences in body types among ethnic groups.
“This is why some people can be ‘TOFI’—Thin on the Outside, Fat on the Inside,” Dr. Jayadevan noted. “Someone might have a normal BMI but still be at risk for health problems because of fat stored in unhealthy places.”
What are these “unhealthy places”? Mainly, it refers to abdominal obesity. But it’s not just about a big belly—it’s about visceral fat, which builds up deep inside the abdomen around organs.
“This kind of fat is especially dangerous because it’s active in the body, triggering inflammation and increasing the risk of serious conditions like high blood pressure, diabetes, heart disease, and stroke,” he explained.
Dr. Jayadevan added, “While height and weight are useful for assessing health risks, relying only on BMI can lead to misjudging a person’s actual risk.”
While BMI is a useful tool for spotting people who might have obesity, experts recommend moving beyond BMI alone to confirm excess body fat and its impact. They suggest using methods like:
The Lancet Commission introduces a new way to define obesity based on how it affects health.
Clinical Obesity: This is when obesity leads to clear health problems like reduced organ function or difficulty with daily tasks such as bathing, dressing, or eating. People with clinical obesity have a chronic condition that needs medical care and treatment.
Examples of signs of clinical obesity include:
Pre-Clinical Obesity: This is when someone has excess body fat but normal organ function. These individuals aren’t currently sick but have a higher chance of developing health issues in the future, like type 2 diabetes, heart disease, certain cancers, or mental health problems. They should get support to lower their risks.
The Commission emphasises that people living with obesity deserve tailored care based on their specific needs, whether they have clinical or pre-clinical obesity.
Care for Clinical Obesity
For those with clinical obesity (where excess body fat is already causing health problems), the focus should be on improving or restoring body functions affected by obesity—not just losing weight. Treatments might include:
The type of treatment should be chosen after discussing the risks and benefits with the patient. Importantly, health insurers should recognise clinical obesity as a chronic illness in its own right and not require the presence of other diseases (like type 2 diabetes) for coverage of treatments.
Care for Pre-Clinical Obesity
People with pre-clinical obesity (who have excess body fat but no current health issues) need a preventive approach. This might involve:
“This new approach ensures that adults and children with obesity get care that matches their needs, without over diagnosis or unnecessary treatments,” said Professor Louise Baur from the University of Sydney, in the statement. It also helps healthcare systems save resources while providing better care.
(Edited by Ananya Rao)
