There is now a study to show that women may just get a bit heavier after marriage. But it works quite the opposite for men, who tend to lose their shape and put on weight after a divorce.
Older people tend to put on weight after these sudden life changes like a marriage or a divorce, depending upon the level of physical activity. The younger lot is still able to battle weight issues before it overtakes them.
Women tended to gain weight in the two years after marriage and for men it was the years immediately following a divorce which turned out to be a problem for their weight.
The reasons could well be that women post marriage get so involved with the home and hearth that they progressively have less time for exercise. On the contrary, men after a divorce, do not find much time for fitness related activities, as they need to make time for domestic chores, which they didn't have to bother during their days of marriage.