{"id":7077,"date":"2026-03-27T22:28:40","date_gmt":"2026-03-27T22:28:40","guid":{"rendered":"https:\/\/www.healthoptibody.com\/?p=7077"},"modified":"2026-03-29T11:22:06","modified_gmt":"2026-03-29T11:22:06","slug":"bmi-system-often-misclassifies-people-as-overweight-or-obese-research-finds","status":"publish","type":"post","link":"https:\/\/www.healthoptibody.com\/?p=7077","title":{"rendered":"BMI system often misclassifies people as overweight or obese, research finds"},"content":{"rendered":"

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More than one in three adults may be misclassified by BMI \u2013 the standard test used by doctors to decide if people are a healthy weight \u2013 leaving millions with the wrong picture of their health.<\/p>\n

The score is calculated using a simple formula based on height and weight \u2013 but new research suggests it may be far less reliable than many assume.<\/p>\n

The findings add to mounting evidence that BMI is not fit for purpose \u2013 and can give a misleading picture of a person’s true body fat and risks.<\/p>\n

Researchers at the University of Modena and Reggio Emilia, the University of Verona and Beirut<\/a> University compared BMI classifications with dual-energy X-ray absorptiometry (DXA) \u2013 the gold-standard method for measuring body fat.<\/p>\n

The study, published in the journal Nutrients and due to be presented at this year’s European Congress<\/a> on Obesity in Istanbul, analysed 1,351 adults aged between 18 and 98, most of whom were women and all of White European background.<\/p>\n

Based on BMI, 1.4 per cent were underweight, 58 per cent a healthy weight, 26 per cent overweight and 14 per cent obese \u2013 figures broadly in line with population estimates in Italy<\/a>‘s Veneto region.<\/p>\n

But DXA scans told a different story.<\/p>\n

More than a third of people classed as obese by BMI were actually only overweight.<\/p>\n

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\"According<\/div>\n<\/div>\n

According to the most recent health survey data for England, around 64 per cent of adults are either overweight or living with obesity, based on BMI<\/p>\n<\/div>\n

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\"Under<\/div>\n<\/div>\n

Under the BMI system, a score of 18.5 to 25 is healthy. A score of 25 to 29 counts as overweight, and 30-plus means a person is obese, the stage at which chances of illness rocket<\/p>\n<\/div>\n

Among those labelled overweight, more than half were misclassified \u2013 most were in fact a healthy weight, while a smaller proportion were actually obese.<\/p>\n

Even among those deemed a healthy weight, BMI got it wrong in around one in five cases.<\/p>\n

The biggest discrepancy was seen in people classed as underweight \u2013 two-thirds of whom were found to be a healthy weight based on body fat measurements.<\/p>\n

Overall, DXA suggested slightly lower rates of excess weight, with 23 per cent overweight and 13 per cent obese.<\/p>\n

Professor Marwan El Ghoch, who led the study, said: ‘Over a third of adults are misclassified when relying on BMI, which overestimates underweight, overweight and obesity compared with actual body fat measurements.’<\/p>\n

Professor Chiara Milanese, co-author, added: ‘Even when BMI and DXA find similar overall rates, the people identified are not always the same. This shows BMI can misrepresent weight in adults of different ages and genders.’<\/p>\n

One key limitation of BMI is that it cannot distinguish between fat and muscle \u2013 meaning someone with high muscle mass may be labelled overweight, while another person with higher body fat but less muscle could fall within the ‘healthy’ range.<\/p>\n

The researchers say BMI should be used alongside other measures, such as waist-to-height ratio or skinfold tests, to give a more accurate picture of health.<\/p>\n

They also called for further studies to assess whether similar misclassification occurs in more diverse populations worldwide.<\/p>\n

Their findings echo calls from 58 international experts for a broader definition of obesity that includes measures such as waist circumference and fat distribution, rather than relying on BMI alone.<\/p>\n