I lost 10 lbs in the first 2 months when I started Lamictal (same drug as Lamictin...just different name). I told my neuro and he said it's very common to lose weight when you first start any form of lamotrigine.

You should be taking vitamins on Lamictal anyways. I went out and got a pre-natal. I was always really tired and could take a nap everyday after class. Turns out I was having seizures in my sleep and not getting a good nights sleep ever. Got on lamictal AND started taking a pre-natal. This has all the vitamins and minerals you need. My neuro told me to take it simply bc I'm sexually active and at child bearing age. He said I need to even though i'm on birth control bc if I were to accidentally get pregnant, lamictal could cause severe birth defects.

I suggest going out and getting a pre-nata vitamin. You really should drink more water. I don't generally like drinking just water but, if you have a craving for salty foods, that's an indication that you are dehydrated.

I agree with Perna in keeping a food diary. It helps you be more conscious about what you're eating throughout the day. My bf was complaining about not losing weight so he started keeping a food diary and realized that he was eating without realizing it. You could use this in the opposite way. After a couple days of writing and you realize "man, I go hours and hours without eating" you could shove a little snack in there but not something that will fill you up too much since you are already concerned with being underweight. Try something NOT filling. I can't believe I'm advising someone to eat empty calories! haha