Lose weight while pregnant?

I'm 12 weeks pregnant and weigh 240 lbs so I'm overweight. This pregnancy has been a lot different from my first but NOTHING sounds good to eat or drink ever. I get to the point where I wanna cry because I'm hungry but once the food is in my mouth it's just blah and don't wanna eat anymore. I weighed myself and I've lost a couple lbs. So my question is.. is it okay to lose weight while pregnant?