Looking for Time Travel Weight Gain Story

I'm looking for a story about a guy who uses a time machine to go back in time and change aspects of his wife's life to make her gain weight. He gets her to stop smoking before the wedding, take part in an experimental pill during college, and eventually crosses paths with his wife going back in time to encourage him to like larger women. It ends with him coming home to find his wife almost immobile returning home from work. Any help would be appreciated in finding it. Thanks!