TUESDAY, Nov. 6, 2007 (HealthDay News) -- If you're one of the millions of Americans carrying excess weight, a pair of new studies has good news and bad news for you. It turns out that a little extra weight may not shorten your life but may make it harder to perform everyday activities as you get older.
The studies, which are published in the Nov. 7 issue of the Journal of the American Medical Association, assessed the effect that weight has on mortality and disability as people age.
The first study found that obesity is associated with functional impairments, such as the inability to bend over to pick something up. The second study compared mortality rates in people of all different weights and found that weight affected the most likely causes of death, with underweight people most likely to die of non-cancer, non-cardiovascular causes and obese people most likely to die from cardiovascular disease or obesity-related cancers.
"People know that obesity places them at increased risk of diabetes and heart disease, but I think people don't always think about how the increased weight may affect quality of life and to do the things you want to do," said the author of the first study, Dawn Alley, a Robert Wood Johnson Health and Society Scholar at the University of Pennsylvania.
Knowing the potential effects of overweight and obesity is becoming increasingly important as Americans' waistlines are ever-increasing. According to the statistics from the U.S. Centers for Disease Control and Prevention, the incidence of obesity in American adults has risen dramatically from the 1970s, when 15 percent of the population was considered obese. Today, that number has more than doubled to 33 percent.
Being overweight increases your risk of high blood pressure, diabetes, heart disease, stroke, arthritis and some cancers, according to the CDC.
Many of these conditions can be controlled, at least partially, by medications, and some research has suggested that may be why obese people today may be healthier than they were a generation ago, according to background information in Alley's study. What hasn't been well-assessed up to this point, according to Alley, is what effect overweight and obesity may have on day-to-day living.
Alley and her colleague, Dr. Virginia Chang, compared two sets of data collected for the National Health and Nutrition Examination Surveys (NHANES). They looked at data from 1988 to 1994 and compared it to data from 1999 to 2004 on Americans over age 60.
The researchers looked for difficulties in two disability assessments: functional impairment and activities of daily living (ADL). Functional impairments include the inability to bend over to pick something up, walk one-quarter mile, walk up 10 stairs, lift 10 pounds and stand from an armless chair. Activities of daily living are more basic skills, such as the ability to feed and dress yourself.
Functional impairments increased 5.4 percent between the two study periods for obese individuals. During the final study period, obese people had nearly a threefold increased risk of a functional impairment compared to normal-weight peers. That represents a 43 percent increase in the likelihood of being functionally impaired for obese people, versus their counterparts of normal weight, the study said.
While the odds of having an activities-of-daily-living impairment didn't increase between the study periods, the odds of an obese person experiencing an activities-of-daily-living impairment were double that of a normal-weight person, because people of normal weight saw a decrease in ADL impairments.
"Obese elderly people have a higher risk of being disabled, and the gap is increasing," Alley said. "Obese older persons are experiencing a potentially preventable impairment. This is just one more reason we need to be concerned about obesity."
In the second study, U.S. government experts looked at specific causes of death based on weight. They also used data from NHANES but went back to 1971 and followed up through 2004.
Interestingly, they found that being overweight -- that's a body mass index (BMI, a ratio of weight to height) of 25 to 29.9 -- was not associated with an increased risk of death from cardiovascular disease and cancer. But overweight was linked to a decreased risk of death from non-cancer, non-cardiovascular disease causes. Being underweight -- a BMI of 18.5 or less -- was associated with a significantly higher risk of death from non-cancer, non-cardiovascular disease causes, according to the study.
Obesity -- defined as a BMI over 30 -- was associated with increased cardiovascular disease mortality. When the two groups -- overweight and obesity -- were combined, the risk of death from diabetes or kidney disease was higher. And, obesity was associated with an increased risk of death from obesity-related cancers, such as breast cancer.
"The message here is that it's not just that if you're heavier, you're at a higher risk of death from all diseases. It's a little more complex than that," said the study's author, Katherine Flegal, a senior research scientist at the National Center for Health Statistics at the CDC.
For advice on losing weight, visit the U.S. Food and Drug Administration.