as long as you are eatting health and not starving yourself baby is fine. just eat small meals thruout the day and snack on fruits veggies cheese anything healthy and you should be ok. if worried talk to your dr though and they will let you know if there is something to be concerned about.
I have lost 20+lbs since finding out we are expecting. My doctor said its OK as long as the baby is getting the proper nutritions from your eating habbits!
I am 17w and have lost 22lbs due to horrible morning sickness. Try to snack as much as possible and to take your vitamins, even if you loose due to vomiting at least a part is being kept in. Also keep hydrated!! Good luck