According to a JAMA study<\/a> published last week, the new index combines measurements like waist circumference, waist-to-hip ratio and waist-to-height with an individual\u2019s BMI to more accurately capture body fat distribution and distinguish body fat from muscle mass.\u00a0<\/p>\n When body measurements were incorporated, the researchers found that 4 in 5 U.S. adults who had a BMI classified as overweight would actually be considered obese. An additional 38% of people with a \u201chealthy\u201d BMI would also be reclassified as obese.\u00a0<\/p>\n Just looking at BMI, the prevalence of obesity among U.S. adults was 40% from 2021-2023, according to<\/a> the U.S. Centers for Disease Control and Prevention. Whether the updated figure is truly a better reflection of the obesity epidemic in the U.S. or reason for the commission to tweak its index is up for debate.<\/p>\n \u201cI was shocked,\u201d said Dr. Maria Escobar-Vasco, an endocrinologist and program director of UT Health San Antonio\u2019s Endocrinology, Diabetes and Metabolism Training program. \u201cObesity is certainly an epidemic, and we\u2019re seeing rising incidence and prevalence of obesity, but 75% [seems high].\u201d<\/p>\n Obesity rates in the U.S. have skyrocketed since the early 1970s, when the BMI measurement was introduced and adapted by health care providers. At the same time, a larger conversation has grown around the complex causes of obesity, the stigma surrounding it, and whether obesity is a chronic disease itself (as the CDC and American Medical Association label it) or simply a risk factor for other diseases, like metabolic disease and type 2 diabetes, for example.<\/p>\n Dr. Aaron King, a family medicine physician with the Baptist Health System, said it\u2019s hard to say what the 75% figure truly reflects because obesity still lacks an agreed upon and well-defined definition. The Lancet Commission was created in part to provide a more concrete answer to these questions.<\/p>\n \u201cI think when you draw the line that\u2019s always a question that is up for a little bit of debate,\u201d King said. \u201cBut I think if you\u2019re asking the question, \u2018Do I think that 75% of U.S. adults have or are at high risk for developing metabolic disease?\u2019 I think what we\u2019re finding in the data is yes, sadly.\u201d<\/p>\n What more researchers agree on is that BMI alone is not a reliable gauge for healthy weight ranges, and updating it would help providers more accurately tease out the interactions between obesity and the diseases that often accompany the condition.\u00a0<\/p>\n The problems with BMI and defining obesity<\/p>\n The BMI formula is simple: your weight (in kilograms) divided by your height (in meters) squared. Anything 30 and above is considered obese, and 40 and above is considered extreme obesity. You can find a full BMI table<\/a> here.\u00a0<\/p>\n BMI doesn\u2019t take into account adipose tissue (body fat) versus muscle mass, bone density, and importantly, the distribution of body fat. As a result, BMI both overestimates and underestimates obesity.<\/p>\n \u201cThe classic example is, you can have a weightlifter who is 10% body fat or less, and might have a BMI over 30, which will classify as obesity,\u201d King said. \u201cBut of course, all that weight is solid muscle, and that person likely doesn\u2019t have any metabolic disease and certainly doesn\u2019t have truncal obesity. And then you can also have people that have a BMI around 25 that have a normal BMI, and yet they might have truncal obesity and be at risk for disease.\u201d<\/p>\n Truncal obesity, or excess stomach fat, also known as visceral fat, is especially associated with insulin resistance, metabolic disease, cardiovascular disease, among other comorbidities. On the other hand, fat stored around the hips, buttocks and thighs known as gluteofemoral fat plays a protective role<\/a> against metabolic and cardiovascular disease.<\/p>\n The Lancet Commission hopes to address this flaw in BMI by including waist circumference, waist-to-hip ratio and waist-to-height measurements, helping health care providers screen for greater disease risk.\u00a0<\/p>\n \u201cThe distribution of the fat makes a difference,\u201d Escobar-Vasco said. \u201cInside of our belly, we have a lot of different very important organs that you need to be fully working. The liver, for example. If we don\u2019t have any more fat tissue that can accumulate that extra fat, it\u2019s going to go into the liver. And so that\u2019s when we start having issues with what used to be called fatty liver disease.\u201d<\/p>\n![\"\"](\"https:\/\/www.europesays.com\/us\/wp-content\/uploads\/2026\/01\/UTHealth_DiabetesBMIIndex_WeightManagementLoss_05_01.07.2026_AmberEsparza.jpg\")
Dr. Maria Escobar-Vasco says medical offices should incorporate waist measurements into standard doctor visits when checking a patient\u2019s BMI to get a more accurate picture of a patient\u2019s health versus going off of BMI alone. Credit: Amber Esparza \/ San Antonio Report<\/p>\n
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Registered dietician and diabetes educator Elizabeth McKenzie talks to patients about meal planning to manage diabetes at UT Health San Antonio\u2019s office of Endocrinology, Diabetes, Obesity and Metabolic Health on Wednesday. Credit: Amber Esparza \/ San Antonio Report<\/p>\n