How to not gain too much weight in pregnancy?

So, I had a doctor appointment on October 27th, and my last one was yesterday, December 6th. I had gained 9 pounds in that amount of time, and the doctor told me that even though it's the holidays I need to be careful so I don't gain too much weight before the baby gets here..

So, mommas, what are some ways to prevent weight gain when you're hungry all the time!! (Mind you my first 2 appointments I hadn't gained anything, then I gained 4 pounds, then 9 pounds...)