I was about 15-20 lbs over weight when I became pregnant. The first 2 trimesters I lost weight and was concerned but my dr said it was totally fine. He said if the baby was not growing like she should he would be concerned as well but everything was normal. He also told me that dieting is ok while pregnant.....although you don't want to starve yourself or use any type of weight loss products. If you just eat right your body and baby will use what it needs. Also exercising is so good for you and your baby. I would talk to your Dr on what exercises would be best for you though....because all women and pregnancies are different. Good luck and good job wanting to stick with your goal, thats awesome!!!
It's best to talk to your Obstetrician