Much like the old saying goes, looks can be deceiving. Research out today shows that a substantial number of people with so-called “normal” body mass index still have health problems related to obesity.

Scientists at the University of Southern California studied nationally representative data on Americans and found roughly a quarter of people with normal BMI and half of people with an overweight BMI still met the standard for obesity under a recently developed criteria. As a result, the researchers say, many of these people likely aren’t getting the optimal care they need.

“Since most doctors are focused on BMI to screen for obesity-related conditions, this is a population that might not be getting enough attention for screening and treatment of obesity-related conditions,” lead study author Brian Lee, a hepatologist at Keck Medicine of USC, told Gizmodo.

Clinical obesity

BMI is calculated using a person’s weight and height, with obesity classically defined as having a BMI of 30 and over.…