According to Psychologist Tene Lewis of Rush University Medical Center (in USA Today) "Under stress people conserve more fat, and we think that may be what's going on here."
A new study indicates that the stresses of middle age can make women who have suffered distressing experiences more likely to gain weight. Researchers asked 2,000 women in their 40s to relate any unhappy experiences from the previous year, then tracked their health through menopause. The more stressful events that women reported, the more weight they gained. It wasn't just because they ate more; traumatic events actually reprogrammed their metabolisms.