I have been on a gluten free diet for 5 years. It was tough in the beginning, but I have really gotten use to it - it's a very healthy diet.
When I was first diagnosed in 2006 at the age of 24 I weighed 184 pounds, and I'm 6"4". I was very skinny and looked sickly.
5 years later - I weigh 206 pounds. I got tired of everyone calling me skinny, so I joined a gym last year. Best move of my life.
I am extremely sensitive to gluten, so it was tough finding high quality protein products and workout supplements. Here are my recommendations:
Protein powder - Solgar Whey to go protein - excellent quality, 20grams of protein per serving. I buy it in larger quantities at Vitacost. Wegman's also sells it in smaller containers. I like the natural vanilla.
Preworkout - Jack3d Raspberry lemonade - awesome flavor. I only take 1-1.5 scoops before my workout. This product works!!!! I could hit the weights for an hour plus, and in the end, I'm not even tired.
Post workout - Proasis protein shots. Excellent taste. All natural and allergen free. 2.9 ounces has 25g of protein. Wegman's sell these as well.
Proetin bars - as stated above Purefit are awesome. Best if you buy by the box of 15, usually around $28 a box. Berry almond, Peanut Butter, and almond crunch are excellent.
Also, I buy the Organic food bar "Protein bars". These are soy & dairy free, and have 22g of protein per bar. Excellent taset, made from almond butter. Buy them by the box of 12 at Vitacost at around $25-$26 a box.
Add these into an additional 3 healthy mneals with lean meats, veggies and fruits, you'll be putting on lean muscle in a few weeks. I also take a multivitamin each day as well.
Hope this helps,