A study by Weill-Cornell Medical College, in New York, showed that whilst BMI recorded 26% of study participants as obese, an alternative measure, using X-rays, suggested 64% of participants were obese.
The study was published in the scientific journal PLoS One on Monday. The X-ray diagnosis was a technique known as a dual-energy X-ray absorptiometry scan, or DXA scan for short. The DXA scans measured fat composition of the participants and calculated obesity standards by the measures used by the American Society of Bariatric Physicians. 1,393 patients from researcher, Dr Braverman’s Manhattan practice took part in the study.
The Body Mass Index, BMI, measures a person’s height against their weight to give a rough indication of a person’s body fat. Whilst BMI is easy to measure, Dr Braverman states the system tends to under-diagnose obesity: “BMI works about half the time. That’s why I call it the baloney mass index”.
According to the BMI system, a score between 25 and 29.9 is considered to be overweight and a score above 30 as obese. Dr Braverman notes that weight loss related to loss of muscle mass in age, particularly in women, exacerbates the under-diagnosis of obesity and suggests that obesity in women should be recorded at a BMI score of 24 and in men a BMI of 28.
Obesity is closely linked with type 2 diabetes and BMI is one of the factors used to identify those at higher risk of diabetes. The University of Leicester has suggested a need to adjust BMI scores for obesity for different ethnities. Dr Braverman’s research could lead to calls for BMI scores to be adjusted by gender and age as well.

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