Traditional conceptions of obesity could change radically. In a new report released this week, a widely supported group of scientists is calling for significant changes to the way obesity is diagnosed and classified.
More than 50 obesity experts from around the world produced the report, as part of the committee behind it Lancet. Among other recommendations, the group calls for the gradual abolition of body mass index (BMI) as the sole criterion for diagnosing obesity. They also argue that obesity should be categorized into two different types, depending on how much harm a person’s condition is likely to cause them.
A special goal of the commission was to establish objective but nuanced criteria for diagnosing obesity. Currently, obesity is diagnosed solely by a person’s BMI, which is calculated using a person’s weight and height. People with a BMI greater than 30 are considered obese, and severely obese are those with a BMI greater than 40 (in some parts of the world, lower BMI cut-offs are used to account for population differences in average population size).
While BMI is an easy-to-obtain and trackable measure, it often fails to convey the whole picture, commission experts say — a criticism shared by many other public health experts. expressed in the past. The harm associated with obesity is primarily caused by excess body fat, and BMI may sometimes not be adequately correlated with this. A very fit person might have a high BMI but low body fat, for example, while someone with a so-called “normal” BMI might have a risky amount of body fat. The distribution of excess body fat can also vary from person to person, as can the health risks associated with that fat. Too much fat around one’s waist or around vital internal organs like the liver and heart is usually more dangerous than excess fat in the skin under the arms or legs, for example.
Experts are not urging doctors to completely abandon BMI as a tool for diagnosing obesity, but to use it alongside other body measurements. This includes measuring waist circumference, waist-to-hip ratio, or waist-to-height ratio. Medical professionals should use at least two measurements of body size to diagnose people suspected of being obese, researchers say, and one other measurement besides BMI. Instead, doctors can collect direct measures of a person’s body fat, such as by performing a bone density test, commonly known as a DEXA scan. People with a very high BMI (over 40) can still be assumed to have excess body fat, they added.
“If implemented—people with obesity (BMI near or at or above obesity) should have at least one other measure of body size (eg, waist circumference in most cases or DEXA if available) to confirm accurate detection of excess body fat—it would confirm that someone is indeed obese and not just, for example, a muscular person with a high BMI,” Francesco Rubino, an obesity researcher at Kings College London and chair of the panel, told Gizmodo in an email.
Rubino and his panel also recommend that doctors group obesity into two broad categories: preclinical and clinical obesity. Just having high body fat may not negatively affect your health, experts note, so they’ve created a list of criteria (18 for adults, 13 for children) to identify when someone’s obesity is likely to cause other physical problems. Someone with obstructive sleep apnea, severe knee pain, or poor cardiovascular health suspected to be related to their excess body fat would be classified as clinically obese, for example, while someone with obesity but no signs of abnormal classified organ functions as preclinical obesity.
“Reframing the clinical effect of obesity to explain how obesity can be a risk factor for other diseases and a direct cause of disease is warranted. A definition of clinical obesity thus addresses a gap in the characterization of obesity as a direct cause of ill health and may be an effective way to address widespread misperceptions and biases that misguide decision-making among patients, healthcare professionals, and policy makers,” the authors wrote in their report. published Tuesday at Lancet Diabetes & Endocrinology.
People with preclinical obesity may still be at higher risk for future health problems, but the difference allows for more personalized obesity care, Rubino says. While people with clinical obesity should be treated immediately with effective weight loss treatments, which may include newer drugs like semaglutide (the active ingredient in Ozempic and Wegovy) or bariatric surgery, doctors may use a less intrusive approach with someone who is preclinically obese, depending on their level of risk.
“These strategies can be as simple as suggesting monitoring over time and lifestyle changes aimed at feasible weight loss for people at low risk (even modest weight loss can go a long way in preventing obesity-related diseases), or involve more active forms of intervention if assess the risk as particularly elevated (due to other factors in addition to obesity itself, such as family history, abdominal fat distribution, other conditions, extreme weight and especially a combination of the above), said Rubino.
The group’s recommendations are ultimately just that. But their conclusions are largely supported by health organizations around the world—76 in all, including the American Heart Association in the US, the Royal College of Physicians in the UK and the World Obesity Federation. There are still important big questions about the nature of obesity that need to be answered, such as the exact prevalence of preclinical to clinical obesity (by the current definition of BMI alone, more than 1 billion people worldwide are thought to be obese). But according to report co-author Robert Eckel, an endocrinologist at the University of Colorado School of Medicine, the new guidelines should greatly help both doctors and people living with obesity.
“The intent of our work was to optimize and individualize patient diagnosis, and risk versus care,” he told Gizmodo. “We think this characterization will benefit patients, healthcare providers and the healthcare that follows.”