According to this week's issue of National Enquirer, Mary-Kate Olsen has packed on over twenty pounds, and the magazine is speculating that it's because MK is pregnant.

The magazine does not come outright and claim this is in fact true. Rather, it just speculates it's a possibility because MK has been looking healthier-her weight is up to 102 pounds-and that she's eager to start a family with Nate. This was supposedly spurred by Heath Ledger's death,
because Heath told Mary-Kate that becoming a father was one of the best and most rewarding things he's ever done.
This claim contradicts her statement in Influence, where she says she'd rather be a cool aunt or godmother.
Regardless of how or why MK has gained weight, she does look noticeably healthier. She seems happier too.