Exercise is good for your waistline -- but it's a writing exercise

"We have this need to feel self-integrity," says Christine Logel of Renison University College at the University of Waterloo, who cowrote the new study with Geoffrey L. Cohen of Stanford University. When something threatens your sense that you're a good person, like failing a test or having a fight with a friend, "We can buffer that self-integrity by reminding ourselves how much we love our children, for example," she says.

For this study, the researchers recruited 45 female undergraduates who had a body mass index of 23 or higher. A body mass index of 18.5 to 24.9 is considered normal weight; 58% of the women were overweight or obese. Each woman was weighed, and was then given a list of important values, like creativity, politics, music, and relationships with friends and family members. Each woman ranked the values in order of how important they were to her. Then half the women were told to write for 15 minutes about the value that was most important to her. The other half, a control group, were told to write about why a value far down on their list might be important to someone else.

The women came back between one and four months later to be weighed again. Women who had written about an important value lost an average of 3.41 pounds, while women in the control group gained an average of 2.76 pounds, a pattern of weight gain that is typical for undergraduates.

"How we feel about ourselves can have a big effect," Logel says. "We think it sort of kicks off a recursive process." Maybe when one of the women who wrote about an important value went home that night, she felt good about herself and didn't eat to make herself feel better. Then the next day snacking wasn't as much of a habit, so she skipped it. Over a few months, that could make a real difference in her life.

Many studies have found that even briefly thinking about values can have a big effect on situations where people feel a threat to their integrity. For example, Cohen used the same technique on minority seventh-graders who were underperforming relative to their white peers. Those who did the exercise were still performing better years later.

It's too soon to say whether this could work for everybody; the women in the study didn't know that writing about values was supposed to help them live better (although they may have wondered why this psychology study required a weigh-in).

"My dream, and my research goal, is to get this to the point where people can do it deliberately to benefit themselves," Logel says. In the meantime, she carries around a keychain that reminds her of a value that she considers to be important. And everyone else can do that, too. "There's certainly no harm in taking time to reflect on important values and working activities you value into your daily life," Logel says.