I just came across this i thought it was interesting

Women tend to put on weight and eat more unhealthily
when they move in with a boyfriend, a study suggests.

But Newcastle University dieticians said, in a review of seven studies, that men seemed
to become more healthy after they began co-habiting.
The study in Complete Nutrition suggested women's diets tended to increase in fat and
sugar after they began living with a partner.
The team said diets change because each partner tries to please the other.
They looked at a range of studies focusing on the eating and lifestyle habits of thousands of subjects who were either married or who co-habited and found the same theme.

Men found themselves eating lighter, healthier meals and more fruit and vegetables, while women moved towards the creamier, heavier dishes like curries and rich pasta meals favoured by their partners.
One study of 20 US couples found men started to eat less meat, while women began eating more.
Another study of 9,043 adults in the US found marriage itself led to women putting on weight, and moving out of marriage was linked to weight loss in women.

The authors suggested this was caused by more structured eating and less time for exercise within marriage.

you can check out the whole research

http://news.bbc.co.uk/2/hi/uk_news/4879380.stm

Little wonder some women's weight balloon after marriage -- just kidding.

The thing is, each partner tries to please the other -- that's something not found after marriage.

It's true! My wife started getting fat as soon as we started living together.

Yeah, because they tend to get too comfortable and let go of themselves

Mystique:

Yeah, because they tend to get too comfortable and let go of themselves

So I heard.