Lack of religion can keep you slim.

• Position: Your Life - Brief article

Could it be the potato salad? Young adults who frequently attend religious activities are 50% more likely to become obese by middle age as young adults with no religious involvement, according to a study by Northwestern University, Chicago, Ill.

"We don't know why frequent religious participation is associated with development of obesity, but the upshot is these findings highlight a group that could benefit from targeted efforts at obesity prevention," suggests Matthew Feinstein, the study's lead investigator. "It's possible that getting together once a week and associating good works and happiness with eating unhealthy foods could lead to the development of habits that are associated with greater body weight and obesity."

By tracking participants' weight gain over time, the study makes it clear that normal-weight younger adults with high religious...