Stanford Medicine statistician Maya Mathur, was initially under the impression, based on popular culture and public health advice, that being overweight reduced lifespan. However, she was intrigued to discover research indicating that the life expectancy of overweight individuals (BMI between 25 and 29.9) is not necessarily shorter than that of people with a normal BMI when accounting for factors like age and smoking habits.
Obese individuals at risk of reduced mortality
Two studies from 2013 and 2016 examined the relationship between weight and mortality. The 2013 study, based on 100 studies involving 2.8 million people, indicated that being overweight slightly reduced mortality risk, except for those classified as obese with a BMI of 30 or higher. Conversely, the 2016 analysis of 240 studies suggested a small link between being overweight and higher mortality.
Mathur stated that that from her exposure to public health messages it was evident that being overweight was associated with increased mortality risk. However, after review of the studies she concluded that that the perception is not evidence based taking into consideration available literature.
Mathur with her mother, Vandana Mathur, a practicing physician and biomedical researcher, conducted a survey of nearly 200 primary care physicians in the U.S. to understand their perceptions of mortality risks for overweight individuals, as there was a curiosity if doctors shared common misconceptions regarding this issue. Approximately one in three American adults are overweight but not obese.
Being overweight doesn’t reduce one’s lifespan
In their study published in Epidemiology, they discovered a significant disparity between doctors’ beliefs and medical guidelines. The study revealed that 90% of doctors surveyed believed that being overweight reduced patient lifespans, despite clinical guidelines from the American Heart Association the American College of Cardiology contradicting this notion. This indicates a substantial disconnect between doctors’ perceptions and empirical evidence.
Mathur suggests that the disparity may arise due to confusing messages doctors receive from the medical community. Clinical guidelines indicate that being overweight doesn’t raise mortality risk, yet they advise doctors to inform overweight and obese adults that higher BMI correlates with greater all-cause mortality risk.
