(HealthDay News) -- If excess weight doesn't kill you by old age, it could make your life miserable in the form of chronic health problems and impaired mental fitness.

According to a new study, women who are obese in middle age are almost 80 percent more likely to have multiple health problems by the time they reach age 70.

"Those who gained weight [in adulthood] actually suffered reduced odds of healthy survival," said study author Dr. Qi Sun, a research associate at the Harvard School of Public Health's department of nutrition.

"The key message is that women really need to keep a healthy weight from early adulthood to midlife to enjoy a healthy and long life," he added.

Sun added, however, that the women in the study had nonetheless survived to their eighth decade, meaning they remained healthier than the general population.

The study findings were published in the Sept. 30 online edition of the journal BMJ.

Previous research had focused on how excess weight affects survival, rather than how healthy that survival looks in older adults, said Sun.

The new study is well-timed, given that the U.S. population is not only aging rapidly but ballooning rapidly. Two-thirds of American adults are overweight or obese, up from 14.5 percent in 1976, when this study started.

The study authors analyzed data on 17,065 women participating in the Nurses' Health Study. Volunteers were, on average, 50 years old when the study began with no major chronic conditions or major mental or physical problems.

Twenty years later, only about 10 percent of women had "healthy survival," and obese women were 79 percent less likely to have healthy survival than the slim minority.

Overweight as early as age 18 affected healthy survival the most, although women who were lean in their late teens who later gained weight still had lower odds of healthy survival, the study found.

Every kilogram (2.2 pounds) of extra weight lowered the odds of healthy survival by 5 percent, according to the study.

"We typically see this struggle not only in middle age but even as teenagers. If you struggle as a teenager, you're going to struggle for the rest of your life," said Eugenio Lopez, a registered nurse with the Texas A&M Health Science Center Coastal Bend Health Education Center in Corpus Christi.

And women may be starting out at a disadvantage, Lopez added.

"We typically see more women than men in diabetes programs. Women outnumber men 4-to-1 or 5-to-1," Lopez said. "They're genetically predisposed to hold more fatty cells than men are."

"The data is following common sense," added Dr. Mitchell Roslin, chief of the bariatric surgery program at Lenox Hill Hospital in New York City. "Why do people die? Of cardiovascular disease and cancer, and women die of colon and breast cancer. What has been linked to obesity? Breast cancer, colon cancer and cardiovascular disease."

More information

The U.S. Centers for Disease Control and Prevention has more on healthy aging.
http://www.cdc.gov/aging/