TUESDAY, April 19, 2005 (HealthDay News) -- Being obese may not be as hazardous to some people's health as doctors have feared.
Two new U.S. government studies report that many cardiovascular risk factors in overweight and obese people, with the exception of diabetes, are on the decline. And although there are still more than 110,000 excess deaths each year in America attributed to obesity, that number is below previous estimates.
The findings appear in the April 20 issue of the Journal of the American Medical Association.
Surprisingly, one of the studies also found that being underweight can kill you, too. The researchers found almost 34,000 excess deaths are associated with being underweight, especially in the elderly, according to study author Katherine Flegal, a senior research scientist for the National Center for Health Statistics.
The declining cardiovascular risk factors include high blood pressure, elevated cholesterol and smoking rates, according to the researchers from the U.S. Centers for Disease Control and Prevention. They speculate that improved awareness, better screening and more effective medications are responsible for the falling rates of high blood pressure and high cholesterol in the overweight and obese population. Massive public health campaigns and policies against smoking are cited as a possible reason for the decline in smoking rates.
However, the researchers are quick to point out that their findings don't mean you can just take a pill and it's OK to be overweight.
"Being obese is still associated with a high risk of many health conditions and disability -- certainly diabetes, perhaps some cancers, and it may affect your quality of life. So controlling and maintaining better body weight will still have a huge impact on quality of life and for a number of chronic conditions," said Edward Gregg, author of the second study and an epidemiologist in the division of diabetes translation at the CDC in Atlanta.
The findings seem to run counter to a study published in the April 20 issue of Circulation that found obesity increases the risk of heart disease in both men and women.
Dr. George Fielding, a surgeon at New York University Medical Center's Program for Surgical Weight Loss, agreed with Gregg's endorsement of weight control. "If you're obese, you will get these diseases, like diabetes, high blood pressure and high triglycerides," he said. "It's cool that these diseases are being better treated, but there are still a lot of dead people purely from being overweight."
Flegal's study compared mortality and body mass index (BMI) information from three different National Health and Nutrition Examination Surveys (NHANES) done in the early and late 1970s, and then again in the late '80s and early '90s, to an NHANES study conducted from 1999 through 2002.
The researchers found that being obese -- a BMI over 30 -- was associated with 111,909 excess deaths compared to people with a normal BMI -- from 18.5 to less than 25. Being underweight -- less than an 18.5 BMI -- also contributed to excess deaths, nearly 34,000 of them. However, being overweight -- a BMI of 25 to less than 30 -- didn't appear to cause excess deaths.
In an accompanying editorial, Dr. David Mark, a contributing editor to JAMA, wrote that these estimates appear "to strongly contradict prior estimates published in JAMA." He cited previous studies that found between 280,000 and 414,000 excess deaths were obesity-attributable.
"The magnitude of the differences cries out for explanation of the reasons behind these differences," Mark wrote.
While uncovering these differences may be important from a public health perspective, Fielding pointed out that what's really important to note is that no matter the number, past studies have all found that too many people are dying just because they're obese.
"A man who's 45 with a BMI of 45 will live about 10 years less than someone of normal weight," Fielding said.
In Gregg's study, he and his colleagues examined data from five NHANES studies, beginning in 1960 through 2000, searching for trends in cardiovascular risk factors by BMI.
They found that high cholesterol, high blood pressure and the number of people smoking has declined for all BMI groups. The one disease exception was diabetes, levels of which remained stable throughout the 40-year study period.
Thirty-nine percent of obese people in the early 1960s had high cholesterol, compared to 18 percent in the 1999-2000 survey. High blood pressure was present in 42 percent of obese people in the '60s, and in 24 percent in the later study. And in the 1960s study, 32 percent of obese people smoked, compared to 20 percent in the 1999-2000 study.
"Obese persons now smoke less, and have lower cholesterol and lower blood pressure. Although mortality outcomes are not evaluated in the study by Gregg et al, because of interactions between risk factors, this across-the-board decrease in risk factors across all weight groups could translate to a lowering of the elevated risk of death associated with obesity," Mark noted in his editorial.
Still, all the experts agreed, a healthy body weight is best.
"Maintaining a healthy lifestyle -- by increasing physical activity, eating a healthy diet and following up with health-care providers for testing, screening and necessary treatments -- will help reduce cardiovascular risk factors whether you're lean, overweight or obese," Gregg said.
More information
To learn more about the health risks of being overweight or obese, read this information from the National Institute of Diabetes and Digestive and Kidney Diseases.
