April 19, 2005 - Obesity is a risk factor for death, but the risk appears to be much lower than it was just a few decades ago, according to new research from the CDC.
Two new studies offer compelling evidence that obese people in the U.S. today are healthier than they were in the 1970s and 1980s.
The reasons? CDC researchers who spoke to WebMD credited a combination of medical intervention and public health intervention. Medical intervention includes the increased use of drugs to control blood pressure and cholesterol; public health intervention includes the campaign that convinced millions of Americans to stop smoking.
"This tells us that certain aspects of public health efforts to improve cardiovascular disease risk factors are getting through to obese people as well as lean people," CDC epidemiologist Edward W. Gregg, PhD, tells WebMD.
The two studies are published in the April 20 issue of The Journal of the American Medical Association (JAMA).
The findings come at a time when more Americans than ever are obese, meaning that they have a body mass index (BMI) of 30 or greater. Someone who is 5 feet 5 inches tall and weighs 180 pounds or more would be considered obese, as would a 5-foot-8-inch person who weighed 200 pounds or more.
In one of the two studies, researchers reported that both underweight (BMI of less than 18.5) and obese people were at an increased risk of death compared with people of normal weight. But the obesity-related risk was lower than other studies have indicated.
Using data from a large ongoing study of nutrition and health trends in the U.S., Katherine M. Flegal, PhD, and CDC colleagues estimated that obesity was associated with about 112,000 excess deaths in the year 2000. Other researchers, reporting earlier this year, put the figure at about 400,000.
Surprisingly, no increased risk of death was seen among people who qualified as overweight but not obese -- those who had a BMI of between 25 and 29.9 and are at increased risk of obesity. That would mean weighing between 150 and 175 pounds if you are 5 feet 5 inches tall, and between 165 and 200 pounds if your height is 5 feet 8 inches.
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.