Overweight older adults with stable weight likelier to survive

Some overweight older adults don't need to lose weight to live longer, but could risk an early death if they gain more pounds, according top a study.

The researchers used data from the Health and Retirement Study, a nationally representative survey of Americans born between 1931 and 1941.

The study, led by Hui Zheng, assistant professor of sociology at The Ohio State University, analyzed 9,538 respondents who were aged 51 to 61 when the survey began in 1992. They were re-interviewed every two years until 2008, and the researchers had information on how their body mass index (BMI) changed at each interview and whether they died at any point before December 2009.

Zheng and his colleagues classified respondents into six groups, depending on their BMI at the beginning of the study and how it changed over the 16-year period they were surveyed.

While slightly overweight people (BMI of 25 to 29.9) whose weight was steady had the highest survival rate, those who moved from overweight to obese (BMI 30 to 34.9) were close behind.

The third highest survival rate among the six groups was normal weight individuals (BMI of 18.5 to 24.9) whose weight increased slightly, but stayed within normal range.

Next came the Class I obese (BMI of 30 to 34.9) whose weight was moving upward.

Next to last were normal weight individuals who lost weight. Although the study attempted to control for illnesses among those studied, it may be that many of these individuals dropped weight because of illness.

The most obese individuals (BMI of 35 and over) who continued to add weight had the lowest survival rate of the six groups.

The study has been published online in the American Journal of Epidemiology.