It's a story as old as time.

Boy meets girl. Boy and girl fall in love.

Boy and girl start eating out all the time and they start staying in watching TV while eating pizza and gelato. All of a sudden boy and girl have ballooned three pants sizes.

Yes, the quandary of watching our waistlines while navigating the ups and downs of love is one many of us can relate to.

It's also the subject of a new book titled "Love Me Slender: How smart couples team up to lose weight, exercise more and stay healthy together."

Its authors Thomas Bradbury and Benjamin Karney are the co-directors of the UCLA Relationship Institute. And they join us now.