Being classified as overweight based on the body mass index (BMI) scale does not necessarily lead to an increased risk of death when considered independently of other health factors, a recent study has found. The BMI, a calculation based on an individual’s height and weight, categorises adults into various degrees of body fat.
Individuals with a BMI falling between 25 and 29.9 are considered overweight, while a BMI between 18.5 and 24.9 is categorised as a healthy or normal weight, according to the US Centers for Disease Control and Prevention. A BMI of 30 or higher is classified as obese.
Dr. Aayush Visaria, an internal medicine resident physician at Rutgers Robert Wood Johnson Medical School, emphasises that BMI alone is an inadequate indicator of mortality risk and overall health. He suggests, according to CNN, that additional factors such as waist circumference, other measures of fat distribution, and weight trajectory should be considered.
Experts not involved in the study caution that the findings may be influenced by factors other than BMI. Dr. Baptiste Leurent, a medical statistics lecturer at University College London, points out that using the term “overweight” solely for those with a BMI between 25 and 29.9 is misleading, as it excludes individuals with a BMI above 30, which falls into the obese category.
While the study examines the association between BMI and mortality rates, it does not consider other important outcomes such as quality of life or the development of comorbidities like diabetes or heart disease. Observational studies like this can only establish associations and not causation.
The study analysed data from over 554,000 non-pregnant American adults over the age of 20, comparing BMI levels with deaths that occurred over the following 20 years. The researchers found that mortality risk increased for individuals with BMI levels higher than 27.5, following a U-shaped curve where risk rose as weight increased.
Notably, the study found no significant increase in mortality risk for adults aged 65 and older with a BMI between 22.5 and 34.9, encompassing the range from normal weight to obesity.
Experts stress that, while being overweight may not directly lead to early death, it does contribute to the risk of chronic diseases. Factors like the development of diabetes are of particular concern for individuals in the overweight and moderate obesity range.
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Updated: 06 Jul 2023, 01:35 PM IST