Study finds BMI alone can miss or misdiagnose obesity in millions

Researchers tested an obesity definition that combines BMI with waist measurements and organ-function checks. The approach was proposed by experts in a Lancet Commission report. The researchers analyzed health records from more than 800,000 people in the UK, US, China and Spain, tracking their health for up to 15 years.

The researchers said BMI alone missed obesity in 5-9% of adults and wrongly diagnosed it in as many as 3%. The new definition separates clinical obesity, in which excess body fat impairs organ function, from pre-clinical obesity, where it poses a health risk but has not caused problems. They reported that 80% to 90% of people with pre-clinical obesity did not develop clinical obesity in the next 10 years. Francisco Rubino said individual diagnoses could help guide care, including lifestyle advice, GLP-1 weight loss drugs or surgery.