If you keep track of what you eat..and when...you will be just fine. It does tend to make you hungry at times...but just keep track, you can do this!! I have not been on it long, 75 mg a day, but I have to say that I did not get all loopy, it did not help my sleep at all...but it does help with the pain and extreme fatigue.
If you have control of your well-being...weight gain should not be an issue, so far..it isnt with me anyway.
I've been taking it for 10 months, and yes, I did have weight gain from it, but it appears to be edema; though I have no idea how much I gained b/c I never weigh myself. But I definitely went up a size or 2.
I do not have constipation from it, nor do I have dry mouth. What is weird is...I normally have a very dry mouth, but for some reason, the Lyrica helps my dry mouth. For a while, when you first take it, you might feel strange, kind of spacey, or feel like your brain is out of focus.