January 28, 2013
John DiTraglia MD
Research on the relationship between body mass index (BMI) and lifespan (1) received a significant amount of coverage in print and online. Many sources quote the study’s lead author, Katherine Flegal, a senior scientist at the Centers for Disease Control and Prevention.
The New York Times (1/2, A10, Belluck, Subscription Publication) reports that research published in the Journal of the American Medical Association “found that those whose BMI ranked them as overweight had less risk of dying than people of normal weight.” Although “obese people had a greater mortality risk over all, those at the lowest obesity level (BMI of 30 to 34.9) were not more likely to die than normal-weight people.” The Times adds, “The report, although not the first to suggest this relationship between BMI and mortality, is by far the largest and most carefully done, analyzing nearly 100 studies, experts said.”
USA Today (1/2, Hellmich) reports that Flegal said, “People are sometimes amazed that overweight people have a lower mortality than normal-weight people, but a lot of the research has shown this for a long time.” Flegal “colleagues at the National Center for Health Statistics, part of the Centers for Disease Control and Prevention, reviewed the studies, which tracked three million adults from around the world.” The investigators, “looked at deaths from all reasons and people’s” BMI.
The Los Angeles Times (1/2, Mestel) reports that “the scientists…found that people classified as overweight, with a BMI of 25 to 29.9, died at slightly lower rates - not higher - than those of so-called normal weight.” They also “found that those who were mildly obese, with a BMI of 30 to 34.9, died in no greater numbers than did their normal-weight peers.” However, individuals with a BMI of 35 or more did have shorter lifespans than normal-weight individuals. Flegal “said she and her colleagues could not say what lay behind the apparent survival edge for overweight people.”
Bloomberg News (1/2, Cortez) points out that “the heaviest participants were 29 percent more likely to die from any cause during the course of the studies, according to the data.”
The Wall Street Journal (1/2, A2, Beck, Subscription Publication) reports that Thomas Frieden, director of the U.S. Centers for Disease Control and Prevention, said, “I don’t think anyone would disagree with the basic fact that being more physically active and eating a healthier diet is very important for your health.”
On its website, ABC News (1/2) reports, “On one hand, said obesity experts not involved with the research, the findings suggest that the current widespread use of BMI as a way to determine if one is overweight or obese may need to be reconsidered. Flegal said that the problem may not be the BMI scale, but, rather, how the different rungs on the BMI ladder are interpreted by” physicians.
According to the New York Daily News (1/2, Beekman), “Skeptics immediately attempted to cut the report down to size, noting it failed to account for gender, age, fitness levels and where fat is distributed on the body.”
Medscape (1/2, Tucker) reports, “In an accompanying editorial, Steven B. Heymsfield, MD, and William T. Cefalu, MD, both from the Pennington Biomedical Research Center, New Orleans, Louisiana, caution against relying on weight alone to stratify risk.”
HealthDay (1/2, Reinberg) reports that Cefalu said, “Body mass index simply is a parameter; it doesn’t take into consideration family history, it doesn’t take into consideration smoking, fitness, cholesterol and other factors that should be considered beyond body mass index.”
John DiTraglia (Portsmouth Daily Times) It’s not just me and the Portsmouth Daily Times who are writing about fat science.
1.Flegal KM et al. Association of all-cause mortality with overweight and obesity using standard body mass index categories. JAMA 2012;309(1):71-82