I took 8mg of zofran twice a day for about 6 weeks this pregnancy. It wasn't a cure-all, but it made a world of difference. I still couldn't cook or eat most things, but I was able to eat about a meal a day (something random, always from out) and a few snacks here and there. I gained no weight while I was taking it, but I didn't lose any additional weight. I still avoided any odors/smells/fragrances whenever possible since they still made me gag, but I didn't throw up!
I will second the constipation issue. I suggest *not* taking pre-natal vitamins, just a regular multivitamin, since iron is constipation and PNVs have a lot more iron. I will also say that I will take constipation over vomiting any time
I'm usually very anti-medicine especially when pregnant, but since I had already been treated for dehydration once and had lost 11 pounds, I figured the zofran was the lesser of the two evils. And, it's category B for pregnancy.