A range of factors, from self-confidence to stress to body weight, can make the difference between taking up exercise or staying on the couch, according to a new study.

Researchers found that among 274 middle-aged adults at risk of developing type 2 diabetes, those who were thinner, more confident in their ability to be active, or had lower stress and depression levels were more likely to exercise.

The findings, published in the Journal of the American Dietetic Association, come from a larger study that originally showed that exercise and other lifestyle changes could cut the risk of type 2 diabetes by more than 50 percent in adults at high risk of the disease.

In the current study, researchers re-analyzed the data to see what factors made certain people more likely to boost their activity levels. Linda M. Delahanty, director of nutrition and behavioral research at Massachusetts General Hospital in Boston, led the study.

All the participants included in the analysis had completed questionnaires on self-confidence, stress levels, anxiety and depression at the start of the study.

Overall, Delahanty’s team found, men were more likely than women to already be active at the outset, as well as at the end of the study, two years later.

In addition, people with more confidence in their ability to exercise were more active throughout the study, as were those with relatively lower weights. Men and women with higher stress, anxiety or depression levels were less likely to exercise.

“Our results suggest that programs that focus on improving motivational readiness for physical activity and self-efficacy will be critically important,” Delahanty and her colleagues write.

As an example, they point to women-only fitness programs, which may encourage women who lack self-confidence to give exercise a go.

In addition, the researchers write, health professionals should help adults who are at risk of diabetes to address any depression, anxiety or other psychological problems that may be keeping them sedentary.

Men and women who are particularly overweight, they note, may first need counseling on what types of exercise they can handle, or may need help shedding weight before they become active.

SOURCE: Journal of the American Dietetic Association, May 2006.