I went when I was first diagnosed and have to agree with gemini kiwi as to them being useless unless you get lucky to have one that specializes in IBD. Unless you are trying to learn portion control or for diabetes.
I originally requested a dietician specializing with crohn's patients and was told this one knew what she was talking about. #1 she asked me if I wanted to continue to lose weight. I told her that I had lost 20# in a month and "no I didn't want to lose weight at this time I just want to know how to eat nutritious and make what meals I DO eat count."
#2 She also told me to eat things that I was told not to eat until I called her on it. whole nuts... beef... fiber... For example, I was told when I was in the hospital to eat a low risidual diet 2 weeks prior to the appt to give my intestines a rest and this woman wanted me to eat kashi cereal right away until I asked her: "if you went without fiber for 2-3 weeks aren't you supposed to slowly introduce fiber back into your diet? I told her I didn't feeling like having a blockage and going from no fiber to 10g of fiber doesn't sound appealing.
I would get your information from the internet or from books. Basically I learned it's trial and error. When I was first introducing foods into my diet, I would try something new with the stuff I KNEW worked for me and waited for a reaction. I also kept a journal for about a month so I atleast had a base of some kind of food I could eat. No reaction=add to menu. Reaction=chalk up to it being non crohn's approved for now and wait a while and try it again to see if you get same result before you permanetly axe from diet. ie one day I tried peanut butter and got really bad cramps. 3 weeks later, I tried it again (I LOVE peanut butter) and am fine.
Things you might want to check out....
http://www.mypyramid.gov/ food pyramid
http://www.mypyramid.gov/related_links/index.html related food info links
http://www.cfsan.fda.gov/~dms/foodlab.html how to read food labels
http://www.cfsan.fda.gov/~dms/ds-savvy.html regarding making informed decisions on supplements.
http://www.environmentaldefense.org/documents/4966_fishflyer.pdf information on fish and mercury levels. what things are safer to eat.
hope this helps...