I gain weight
everywhere! 
LOL!
Sorry for being insensitive

I read on your other post that you're an artist? If you work sitting down, that might be the problem (I used to be really pear shaped! People kept asking me when the baby was due!) Maybe doing some sit-ups or yoga, that would exercise that part of the body, would help?
I've heard that eating after 6pm causes you to gain weight. I don't know how true this is. But my friends march me past kebab shops, and don't let me in the kitchen in the evening...
I've also heard that sugary drinks (cola, etc.) causes unusual weight gain, like when girls have a great figure, but secretly have chubby, cullulite-ridden thighs or bottom...
Just a few thoughts... I don't want to encourage you to cut out food if you're underweight! Have a massive smoothie from me

And let me know if this is any help!