According to a study of 6,000 Australian women, shacking up with a man leads to women packing on the pounds. All of the women studied were between the ages of 18 and 23 at the beginning of the study, and by the end of the ten-year study most of them had “partnered” with a man and about half had given birth.

The women who remained single gained the least weight – 11 pounds – while those who had given birth gained an average of 20 pounds. However, the women who were partnered but had not given birth still gained four more pounds on average than the single women.

The study appears to confirm a common, yet usually unvoiced, source of frustration for husbands. Possible reasons for the weight gain cited by researchers include a “more active social life,” although that might seem counterintuitive to many married people, particularly those who have children. Other possible explanations, such as the increasingly sedentary lifestyle adopted by many married women or a sense of complacency (no longer need to find a mate), were not mentioned.