As gyms across the country fill up today with people eager to fulfill New Year's resolutions, a new study may change Americans' views on those extra pounds they're so eager to lose.
Researchers at the Center for Disease Control and Prevention found people who are merely overweight-with a body mass index (BMI) of 25 to 29.9-actually have lower mortality rates than those of normal weight, defined as having a BMI of 18.5 to 24.9.
The study also confirmed the severely obese, with a BMI of more than 35, have a shorter life span than people of normal weight. But those who are mildly obese, with a BMI of 30-34.9, die at comparable rates to people of normal weight.
Previous studies also found this so-called "obesity paradox," but this is the most comprehensive analysis done so far. The study, published online Tuesday in The Journal of the American Medical Association, compiled 97 studies analyzing almost 3 million people from the United States and eight other countries. A total of 270,000 people died during the studies.
On average, overweight people were 6 percent less likely to die during the studies than those of normal BMI, while extremely obese people were 29 percent more likely to die.
The paper did not make any recommendations or explain why the overweight people had a higher rate of survival.
"Our goal is really to summarize existing information and not conclude what people should do, other than follow good health practices, no matter what their weight," study lead author Katherine M. Flegal told the Los Angeles Times.
Some argue the results are inconclusive because BMI is not an accurate measure of body fat or heath risk, as having more muscle mass may increase a person's BMI. Others argue that being thin, especially in old age, is a sign of having a serious illness, which also skews the numbers.
But in an accompanying editorial, obesity researcher Steven B. Heymsfield of Pennington Biomedical Research Center explains how carrying a few extra pounds might be helpful. While packing on too much fat can lead to health complications such as high blood pressure, diabetes, and heart attacks, having a little extra fatty tissue may provide extra energy reserves during serious illnesses and extra cushion to protect bones during falls.
Heymsfield also suggests that people who are overweight are often treated more aggressively by their doctors for blood pressure or cholesterol problems than people of normal weight, leading to earlier detection of health problems.
And so, the best news for those of us who may have overeaten this holiday season: "Not all patients classified as being overweight or having [mild] obesity...can be assumed to require weight loss treatment," Heymsfield wrote. "Establishing BMI is only the first step toward a more comprehensive risk evaluation."