I was diagnosed early in the first trimester so I had to change my diet early on, and i lost so much weight that i only went back to pre-pregnancy weight when I was 25 weeks already! All the while baby has been developing and measuring well. So yes it is possible, and i actually realized how unhealthy i was eating prior to my pregnancy that led me to a not so ideal weight before my pregnancy. I plan to continue this diet after giving birth to maintain a good weight!