I am not 100% what California regulations are. However, to avoid the nutrition certification, why not work with a nutritionist, or dietician of your choice. Networking with people can not only benefit your clients, but benefit yourself through a referral system. You refer clients to them they refer to you. Then you do not have to worry about getting money for a nutrition certification which most likely be very limited anyway. This will help as they will consult with a professional who specializes and also, work with you! I am not sure of people who know how to exercise and not eat, and vise verse. This can also, be done with physicians, and physical therapists to expand your client/patient base.