Extra pounds, on their own, may not be the killer they have been made out to be, a new study indicates.
An analysis of records following patients for six years shows that being overweight or mildly obese was not associated with an increased risk of premature death. Being severely obese was, but only if the extra pounds were accompanied by diabetes and high blood pressure.
"There is currently a widespread belief that any degree of overweight or obesity increases the risk of death, however our findings suggest this may not be the case," lead researcher Anthony Jerant, professor of family and community medicine at the University of California, Davis, said in a statement.
Jerant and colleagues looked at nationwide survey data for 50,994 adults collected beginning in 2000. Body mass index (BMI, an indicator of body fatness) was calculated for each and used to categorize each patient as underweight (BMI of less than 20), normal weight (BMI 20 to less than 25), overweight (BMI 25 to less than 30), obese (BMI 30 to 35) or severely obese (BMI more than 35).
Among those included in the survey, just over 3 percent, or 1,683 participants, died during the six years of follow-up. Deaths were assessed using the U.S. Centers for Disease Control and Prevention's (CDC) National Death Index, a computerized index of death record information. [10 Easy Paths to Self Destruction]
According to their analysis, severely obese people were 1.26 times more likely to die over the course of the study than people in the normal group. But once people with diabetes and hypertension were eliminated from the data, severe obesity was no longer associated with increased mortality.
More mildly obese and overweight people, meanwhile, had similar or even lower death rates than people of normal weight. (In fact, the risk of premature death associated with diabetes was lower for mildly and severely obese people than for lighter people.)
Those with the highest risk of premature death: Underweight people.
Americans have gained a lot of weight in recent decades. During the past 20 years, obesity has increased dramatically. Currently, about 36 percent of adults and 17 percent of children and adolescents are obese, according to the CDC.
Previous research, using older data, found a connection between increasing weight and risk of premature mortality, note the researchers, who suggest their work indicates that this relationship may have shifted as more of the population has put on pounds.
"Our findings indicate that the risk of having an above-normal BMI may be lower than in the past," Jerant said in the statement. "While this study cannot explain the reasons, it is possible that as overweight and obesity have become more common, physicians have become more aware of associated health issues like high blood pressure, cholesterol and blood sugar, and are more aggressive about early detection and treatment of these conditions."
The results of the research are detailed in the July-August issue of The Journal of American Board of Family Medicine.