CDC senior epidemiologist David Williamson, PhD, who worked on the study, says the findings can be considered good news for people with otherwise healthy lifestyles who can't seem to lose those extra few pounds.
"If you are overweight and your parents lived to their 80s or 90s and you have no strong risk factors for heart disease or diabetes, it may be that you can shift your energy and emphasis from weight loss to ensuring that you are physically active every day and eating a healthy diet," he tells WebMD.
Using data from the same ongoing nutrition and health study, CDC researchers also reported a sharp decrease in the rates of three major heart disease risk factors over the past 40 years, especially among overweight and obese adults.
The declining rates of high cholesterol, high blood pressure, and smoking among obese people was so great, in fact, that researchers concluded that their levels of risk factors are lower than that of their leaner counterparts three decades ago.
"Obese people are still at increased risk for various disease outcomes compared to lean people, but over time this outlook appears to have improved," researcher Edward W. Gregg, PhD, tells WebMD.
The one heart disease risk factor that did not decline over time, among all BMI groups, was diabetes. Gregg and colleagues reported a 55% increase in diabetes over the past four decades.
In an editorial accompanying the two studies, JAMA contributing editor David H. Mark, MD, MPH, noted that while the two studies are encouraging, many questions remain unanswered about the impact of obesity on disease and death.
He tells WebMD that among the most important is the role the obesity epidemic among America's children will have on future mortality.
"People are becoming obese at younger and younger ages, and we really don't know the consequences of that in terms of future health," he says.
A Healthy Weight Is Still Important
By Kathleen Zelman, MPH, RD
It's certainly great news that the death rate associated with obesity is less than it was a few years ago -- but don't let this information deter your weight loss efforts.
There is still plenty of scientific evidence showing that weight loss can bring important health benefits. You don't have to be model-thin to be healthy, but losing as little as 5% to 10% of your body weight can help lower blood pressure, cholesterol, and blood sugar and improve your overall health. Another thing that hasn't changed: being overweight is still associated with chronic diseases, such as diabetes.