One in five overweight people will now be diagnosed with obesity.

With the new obesity classification framework proposed by the European Association for the Study of Obesity (EASO), one in five people previously considered overweight will now be reclassified as obese . This new definition better aligns with the biological reality of obesity, says Andrea Ciudin, of the Board of the Spanish Society of Obesity (SEEDO) and head of the Comprehensive Obesity Treatment Unit at Vall d'Hebron Hospital (Barcelona).
Obesity is not simply defined by a number on the scale, but as a disease characterized by an excess and/or dysfunction of fatty tissue that negatively impacts health. For a long time, she explains, "the body mass index (BMI) has been mistakenly used as the sole diagnostic tool. This index, which relates weight to height, was created by a Belgian mathematician to describe the average physical characteristics of the population and was validated solely on male soldiers from France and Scotland, without considering its relationship to health events."
BMI is a measure of body size, but it doesn't directly reflect body composition. Instead, she adds, "obesity involves not only excess total body fat, but also aspects such as its location (subcutaneous or visceral fat) and its functionality. Visceral fat, located in the abdomen, is metabolically active and is associated with diseases such as diabetes, cardiovascular disease, and certain types of cancer."
Thus, a person with a BMI of 25 but unfavorable fat distribution (for example, a waist circumference greater than half their height) may be obese, even if it doesn't appear so based on their BMI, explains Ciudin. "These people have an abnormal accumulation of fat, especially visceral fat, which has been linked to a higher risk of metabolic complications."
According to this classification, 18.8% of adults in the U.S., previously classified as overweight based on their body mass index (BMI), were reclassified as obese, according to a study published in the Annals of Internal Medicine .
The research analyzed cross-sectional and longitudinal data from 44,030 U.S. adults aged 18 to 79 who participated in the National Health and Nutrition Examination Survey (NHANES) between 1999 and 2018.
Despite this reclassification, the researchers observed that the risk of death for these people was similar to that of those with normal weight .
The results suggest that the new EASO framework could be a more sensitive tool for diagnosing obesity in its early stages, although the authors emphasize the need for further studies to assess whether these patients would benefit from specific obesity treatment.
Obesity can be divided into two broad categories : excess fat mass disease, where there is an increase in body volume due to excess adipose tissue; and unhealthy fat, where there may not be as much fat, but rather dysfunctional visceral fat, with inflammation and fibrosis.
In the first case, "people tend to have mechanical complications, such as osteoarthritis, sleep apnea, or gastroesophageal reflux, while in the second, they have a higher risk of metabolic diseases such as diabetes, fatty liver, heart attack, or cancer."
Therefore, the SEEDO expert asserts, "although this new definition increases the number of people classified as obese, these individuals already had associated risks. This is not an overdiagnosis , but rather a more accurate fit with the biological reality of the disease. This approach allows for earlier detection of those at risk who could benefit from appropriate treatment."
abc