Women's Weight Tied to Healthy Aging

Sept. 29, 2009 -- For women, the odds of being healthy at age 70 are best for those who don't gain a lot of weight between ages 18 and 50 and who aren't obese at 50.

That news appears in the "Online First" edition of BMJ.

But millions of middle-aged women are overweight and obese, and they can't go back in time to change that. Researcher Qi Sun, MD, of the nutrition department at the Harvard School of Public Health, doesn't want those women to give up on the possibility of healthy aging.

"The key message from our paper is that to enjoy a healthy yet long life, women need to maintain a healthy body weight throughout adulthood," Sun tells WebMD in an email. "Meanwhile, I believe it is never too late to take initiatives to lose weight (in a safe and healthy way) to maximize the probability to achieve healthy survival," Sun writes.

Sun points out that being physically active, at any weight, is a healthy habit.

"The bottom line is women who are already age 50, no matter what [their] current weight is, can still benefit from physical activity to increase their odds of having wonderful health at later life," Sun writes. "Of course, the best way to maximize the probability of healthy survival is to maintain at least moderate levels of physical activity AND a healthy body weight throughout adulthood."

Tracking Healthy Survivors

Sun's study focuses on "healthy survivors." That's the term Sun and colleagues coined for women they studied who lived to age 70 without any of the following:

• Cancer (except nonmelanoma skin cancer)
• Diabetes
• Heart attack
• Coronary artery bypass
• Congestive heart failure
• Stroke
• Kidney failure
• Chronic obstructive pulmonary disease (COPD)
• Parkinson's disease
• Multiple sclerosis
• Amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease)
• Major impairment of mental skills
• Major limitation of physical function
• Mental health that's less than good (based on scores from a mental health survey)

Data came from a long-term health study of 121,700 female U.S. nurses.

The women answered questions about their height, weight, health, and lifestyle every two years for decades, starting in 1976, when they were 30-55 years old.

About 17,000 women were still alive, with enough data for Sun's team to study, at age 70.

Only 10% of those women qualified as healthy survivors.

Weight and Healthy Aging

Women who were obese at age 50 were 79% less likely than women with a normal BMI at that age to be healthy survivors.

What had happened to the women's weight between age 18 and 50 mattered most.

Women who were overweight (but not necessarily obese) at age 18, and who gained at least 10 kilograms (about 22 pounds) by age 50, had the worst odds of becoming a healthy survivor. Only 18% of those women became healthy survivors.

The more weight the women gained between the ages of 18 and 50, the less likely they were to become healthy survivors.

The study doesn't prove that the women's weight affected their survival. Observational studies, like this one, don't prove cause and effect. And it's possible that the nurses in the study don't represent all women.

However, the results held when the researchers adjusted for these factors: women's age upon enrolling in the study; level of education; marital status; husband's level of education; hormone use after menopause; smoking; various diet patterns; family history of heart disease, diabetes, or cancer; and physical activity.