PMSL, I gained about 10kg in the first 20 weeks! (about 18kg all up)

It all depends on how much you weighed (and your BMI) at the start. I had a friend who lost weight during pregnancy, and ended up about 5kg LIGHTER than her pre-pregnancy weight (she was pretty overweight though...). I definately wouldn't restrict how much you eat, except for making sure you are eating a range of healthy food, and good sized portions. I also wouldn't overdo the exercise if you get back into it (it was the LAST thing on my mind, and the last thing I wanted to do as I was EXHAUSTED my whole pregnancy).