The number you see on the bathroom scale might not tell the whole story. Recent research shows that a notable number of individuals classified as having “normal” weight actually exhibit signs of obesity—and, of course, the associated health risks.
A comprehensive study conducted by an international team examined data from the World Health Organization. They discovered that around one in five people globally with a healthy body mass index (BMI) also show clear indications of abdominal obesity, which refers to excessive body fat. These “skinny-fat” individuals tend to have a higher likelihood of suffering from health issues such as elevated blood pressure, suggesting that doctors might overlook significant health concerns if they focus solely on BMI, the researchers argue.
“Relying just on BMI might not be enough to identify these high-risk individuals for timely treatment,” they mentioned in their paper, published this month in JAMA Network Open.
Obese but “normal”
BMI is determined by a person’s height and weight, with obesity conventionally defined as a BMI of 30 or above. Nevertheless, in recent years, there’s been a push from both patients and healthcare professionals to redefine the parameters of what constitutes obesity.
A collective of obesity specialists, supported by organizations like the American Heart Association, rolled out alternative criteria for diagnosing obesity in January. Their guidelines recommend that physicians use BMI in conjunction with another metric to assess excess body fat or to rely solely on these alternative metrics. One of these measurements is waist circumference.
In this new study, the researchers analyzed data from the WHO STEPS survey, an ongoing initiative overseen by the WHO, designed to help countries monitor risk factors for noncommunicable diseases, particularly those linked to lifestyle. They assessed nearly half a million participants across 91 countries from 2000 to 2020.
Overall, 21% of respondents fell into the category of “normal-weight abdominal obesity,” meaning they had a healthy BMI yet a waist size that categorized them as obese. In comparison to those with a normal BMI and waistline, this group showed higher rates of hypertension, elevated cholesterol, and diabetes.
Beyond just BMI
Recent studies have also emphasized the need to look beyond BMI alone.
For example, a study released earlier this month revealed that almost 70% of Americans now meet this newer definition of obesity; this cohort includes 25% of individuals who have a normal BMI but exhibit other signs of excess body fat, such as waist circumference. The findings indicated that people with skinny obesity are at a higher overall risk for health issues compared to those classified as nonobese. Nonetheless, the authors of the current study claim it is the first to assess how widespread this hidden form of obesity is globally.
Instead of completely discarding BMI, the study authors advocate for its use alongside other metrics to provide a more accurate picture of patients’ cardiovascular and metabolic health.
“Our results indicate the importance of utilizing both BMI and waist circumference together, rather than separately, for a more comprehensive assessment of cardiometabolic risk across various populations,” they noted.
This information should also encourage individuals to schedule a thorough checkup at their next doctor’s appointment, one that takes more into account than just BMI.
