I dont have an issue with putting on weight (I'm actually trying to lose it!) but I did have an issue with a high amount of probiotics in Kefir. I drank a small amount of Kefir just to see if I liked the taste and about an hour later I was curled up on the floor screaming in pain. My nutritionist told me that a lot of people with Celiac have a hard time with high amounts of probiotics at least until they heal more. She doesn't want me to drink any more for a long time until I can work it back in slowly. How long have you been gluten free? Maybe you should hold off on the probiotics until you've healed more??
I have been gluten, dairy, soy and grain free for about 17 months now. 2 months ago I had my second endoscopy with celiac panel and the doctor says everything looked great and healed up.. The weird thing is I have actually taken this specific probiotic before, but never had any issues with it other than a little occasional gas... but then again, last time I took it, I was not particularly having belly issues to start out with other than the normal healing pains..I am starting to think that the pains I am feeling right now are the good bugs and bad bugs waging war.