Several studies have shown that a healthy weight is linked to longevity. Now, researchers have found that maintaining a steady weight after the age of 60 could bring "exceptional longevity" in women.

In the latest study published in the Journal of Gerontology, researchers have found that women who have a stable weight after 60 are likely to live longer than 90.

The researchers from the University of California San Diego, who led the study, examined 54,437 participants enrolled in the Women's Health Initiative, a longitudinal study that investigates the causes of chronic diseases in postmenopausal women.

During the study, the weights of the participants were recorded at baseline, year 3, and year 10. Based on the values, the participants were then classified into three groups: weight loss (those with more than 5% decrease from baseline), weight gain (participants with 5% or more increase from baseline), or stable weight (less than 5% change from baseline).

Out of the total participants, 30,647 (56% women) showed exceptional longevity--a life expectancy beyond the age of 90.

The findings suggest that those participants who lost or gained 5% or more weight from baseline are less likely to live longer when compared to those with stable weight. The study was the first of its kind research that evaluated the impact of weight changes on longevity among women.

"It is very common for older women in the United States to experience overweight or obesity with a body mass index range of 25 to 35. Our findings support stable weight as a goal for longevity in older women," Aladdin H. Shadyab, the first author of the study, said.

The researchers also found that weight loss, when it is unintentional, has a more strong association with reducing longevity beyond 90.

"If aging women find themselves losing weight when they are not trying to lose weight, this could be a warning sign of ill health and a predictor of decreased longevity," Shadyab said.

While conventional weight loss recommendations may not help older women improve their longevity, researchers warn that women in the age group should still follow medical advice and lose weight in moderation if required to improve health or quality of life.