Major weight gain

I am currently 4+ weeks along & I am worried about my weight gain this time around. With my first pregnancy I started out at 120lbs and gained at least 100 lbs by delivery. I got back down to around 145lbs then I got pregnant with baby #2. My highest weight at delivery was 250+ lbs. I am currently 216 lbs and really really don't want the pattern to continue. What do you do to help stay healthy and keep your weight gain controlled?