K.O.
I have a master's degree in Human Nutrition and passed the Registered Dietitian Exam last year.
A great place to start for information is the American Dietetic Association website:
http://eatright.org/cps/rde/xchg/ada/hs.xsl/career.html
If you scroll down to the bottom of that page there's a link to 'Education Flowcharts' which will give you an idea of what the process is to get educated and credentialed.
The ADA also has a listing of accredited education programs. You can take some of the classes online:
http://eatright.org/cps/rde/xchg/ada/hs.xsl/career_401_EN...
I highly recommend going for the RD credential. It does require an internship but you will be better positioned for job opportunities and to offer the best, most current, evidence-based information on food and nutrition to your clients. Registered Dietitians truly are the experts in this field of work. I completed my internship in 6 months and learned so much.
Also, you do have to be licensed by the state of Texas in order to practice here. Here's a link to Texas licensure:
http://www.dshs.state.tx.us/dietitian/default.shtm
Good luck to you!