- A growing body of evidence suggests that a waist-to-hip ratio (WHR) measurement is a better indicator of obesity and health than body mass index (BMI).
- New research suggests that BMI measurements may be significantly underestimating the number of U.S. adults with obesity, which can lead to other chronic diseases.
- Experts say obesity misdiagnoses may be preventing people from getting the treatments that they need.
New research suggests that body mass index (BMI) may be drastically underestimating the number of people in the United States with obesity.
Around a quarter of people considered to have a healthy BMI measurement may actually meet the standard of having obesity, which raises the risk of various chronic health conditions.
Researchers say that half of those classified as “overweight” based on their BMI should be reclassified as having obesity. The findings were published on June 1 in the Annals of Internal Medicine.
The authors said that measurements of abdominal fat may be better indicators of obesity. They noted that people who are misdiagnosed based on BMI may not be getting the medical intervention they need or qualify for pharmacologic or surgical treatments for obesity.
In addition, physicians may not flag these patients as needing lifestyle modifications that could improve their health.
“Many people assume that if their BMI says they are not obese, they don’t have to worry about the many health problems linked to obesity,” said Brian P. Lee, MD, a hepatologist and liver transplant specialist with Keck Medicine and principal investigator of the study, said in a statement.
“Our findings show that millions of Americans may already have obesity-related health impacts and may be missing needed health interventions.”
They concluded that 26% of people with a “normal” BMI and 50% of people with an “overweight” BMI actually qualified as having obesity.
“BMI is problematic because it does not specifically measure body fat and instead reflects total body weight, which includes muscle and bone,” Lee said in a statement.
“So, a muscular person can have a very high BMI but not have excess fat, while someone without much muscle can have a normal BMI but have excess fat causing health problems.”
David Cutler, MD, a family medicine physician at Providence Saint John’s Health Center in California, who wasn’t involved in the study, said that, based on BMI, some professional athletes might be classified as overweight or obese when, in reality, they are in peak shape.
“All you have to do is watch a football game to see that,” he told Healthline.
Mir Ali, MD, a bariatric surgeon, bariatric medicine specialist, and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in California, said that while BMI alone isn’t the most accurate measure of obesity, there are reasons for its use. Ali wasn’t involved in the study.
“I agree that BMI is not the ideal indicator of obesity and that measuring the waist-to-hip ratio offers certain advantages,” he told Healthline. “However, BMI remains the most widely used measure by providers and insurance companies because it is easier to calculate, whereas waist-to-hip measurements can vary.”
In recent years, research has suggested that the waist-to-hip ratio (WHR) may be a more accurate measure of overweight and obesity.
For instance, a
Cutler said he favored waist-to-hip ratio measurements over BMI. “BMI measures weight. The others measure fat. They’re two different things,” Cutler said.
Ali noted that WHR, DEXA scans, and body roundness can more accurately determine whether a person has obesity. “However, these methods have not been widely adopted due to drawbacks like cost and complexity,” he said.
“While BMI fails to account for body composition — potentially categorizing muscular individuals as overweight — it will likely remain the standard until a more effective, simple calculation is established,” Ali continued.
Dan Azagury, MD, an associate professor of surgery at Stanford University and the medical director at the Stanford Lifestyle and Weight Management Clinic, shared similar thoughts. Azagury wasn’t involved in the study.
“BMI is a useful and widely used screening tool for obesity because it is simple and easy to apply,” he told Healthline.
“However, it is not perfect for several reasons. Most importantly, BMI is not designed to assess the health impact of obesity. As a result, two patients with the same BMI may experience very different health effects. In this regard, the waist-to-hip ratio is a better measure, as it more accurately reflects metabolically active fat, which tends to accumulate inside the abdomen rather than around the hips,” Azagury continued.
Cutler said that a critical issue with relying solely on BMI is that people who are overweight may not be getting the information they need on diet, exercise, medications, surgery, and other ways to manage obesity.
“It puts them at higher risk of all the diseases that are associated with obesity,” he said. “This condition needs to be recognized and managed.”
The Centers for Disease Control and Prevention (CDC)
However, a
Even with BMI measurements, the National Institutes of Health (NIH) reports that about
The CDC
The federal health agency adds that non-Hispanic Black adults and adults may have
Obesity can also affect many parts of the body, including the brain, blood vessels, liver, and joints.
“Obesity is a complex, long-term medical condition influenced by genetics, lifestyle, and hormones,” said Ali. “If not properly treated, it can affect every organ system and contribute to diabetes, hypertension, and cancer. Studies also show that obesity can significantly shorten a person’s life span.”
Diet is considered a primary factor in the development of obesity.
When the calories a person consumes exceed those they burn, the body stores the excess as fat, which may lead to weight gain over time.
In addition, the quality of the calories consumed is another important factor. Foods high in sodium, fat, sugar, and refined starches can lead to weight gain. Many processed foods fall into this category.
Other factors, such as a lack of exercise and inadequate sleep, can also contribute to obesity.
Experts say the first step is to know the facts about obesity and receive a definitive diagnosis. From there, people can seek treatment.
“The good news is that obesity can be treated,” said Lee in a statement. “Whether through lifestyle changes, medication or both, we have effective ways to reduce excess body fat and lower the risk of future health problems. The earlier we identify people at risk, the better chance we have of improving long-term health and quality of life.”
Ali said that what a person eats and how much they exercise are key to healthy weight management.
“To lower their risk, individuals should maintain a healthy diet and lifestyle, and consult a medical professional if they face challenges in doing so,” he said.
Azagury said the focus should be more on treatment and less on risk reduction. “Prevention is always preferable,” he said. “However, obesity is a highly complex condition with multiple contributing factors, including genetics, which makes prevention challenging.”
“At this point, our main advantage is the availability of several highly effective treatments,” Azagury said.
“For individuals with obesity, initiating effective therapy — such as GLP-1 medications or surgery — early is important, ideally before health complications develop. For that reason, discussing treatment options with your physician at an early stage is critical,” he said.
Leave a Reply