We had a nutrition consult done with a holistic vet when Elle was young and didnt want to eat... it was a lot of moola, a lot of a travel time, and a HUGE waste of money.
I could have gotten the same or better info researching on my own for free.
Make sure you know what you want and are sure you cant get it on your own, know what you are paying for and what you will be getting for your money.