Omeprazole and weight gain

Hi there, I'm sort of new to this forum. I usually post on the IBS section. I have recently been dx with GERD and was put on omeprazole once daily. I'm sort of over my ideal weight anyway....so before I started taking it I had lost about 13lbs and was really proud of that! But since starting the omeprazole I have gained it all back. Is there anyone else out there that has experienced the same thing, and if so, what can I do now to take the weight off? I exercise 4-5 times a week and haven't changed my diet....I'm sort of at a loss here and don't know what more I can do....having IBS is bad enough because I have to stay away from several food groups. The omeprazole has really helped my gut, but I'm just not sure of a diet program that I can really do to restart my weightloss.

Any suggestions?

Thanks,
db