Four years ago, after reviewing almost 100 scientific articles, a researcher from the CDC concluded that being overweight corresponded with a 6 percent decrease in the risk of premature death.
For the third of Americans who are overweight—and the near 100 percent who worry about it—that was reassuring news. But at the time, sceptics said the findings relied too heavily on BMI as the sole indicator of health. As epidemiologist Walter Willett told NPR, BMI measurements don't take into account someone's fitness or health. A thin person could be ill, putting them at risk of death. Overweight people are also at higher risk for chronic diseases like diabetes and heart disease, affecting their quality of life while they are alive.
Now, four years later, a new study has reaffirmed that scepticism.
"Our findings confirm that there is no benefit of being overweight on risk of death, and indicate that [being] overweight is actually associated with an increased risk of dying," head demographer Andrew Stokes told NPR this week. His research actually found a 6 percent increased risk of death for overweight individuals.
Stokes' study took into account maximum BMIs over a 16-year period, which he said gave a more accurate analysis because they weren't influenced by people who lost weight due to illness.
For the record, an "overweight" BMI is defined as anywhere between 10 to 30 pounds of extra weight (a BMI of 25 to 29.9). But BMI categorises people based on only two measurements—weight and height—not more insightful factors, like muscle mass or location of extra fat. An accurate measurement, according to FiveThirtyEight, is waist circumference, or the ratio of waist size to hip size. Willet in 2013 also suggested that people usually hit their "ideal weight" when they are 20 years old. Any weight change from that number, he said, is worth a second look.