The best thing is to get a degree in Nutritional Science and become a licensed nutritionist.
If you choose to get a certificate you want to make sure you understand what your legal scope of practice includes. This is something it is helpful to talk about with your insurance company before paying for any training. I see that Venice beach talks about this on their site. They seem to be saying that if you use their services you can claim an exception to the legal rule. I think I have heard of a couple of such organizations structuring themselves in this way. I don’t know much about ISSA.
Personally I still think the answer to your question is that it is BEST to get fully trained rather than quickly trained, both to display professionalism, and to diminish possible liability issues.
As far as the two specific certs that you’re asking about: From what I know, ISSA seems to get more detailed with the science component of nutrition while the Venice certification get a lot more into the business aspect of nutrition and even gives you tools to start your business.
So, the knowledge component looks as ISSA is the winner. I personally don’t understand why a person wants to build a business around nutrition coaching with merely a certification so that’s why I don’t see the point as much in the Venice certification.
I do believe that ISSA nutrition cert is much like Precision Nutrition, as they are both un-accredited and are open book tests.
If you’re already ISSA certified than I would run with ISSA, especially if you had a good experience the first time.
I do hope you know, at this point in time, that your profile looks spammish, with the hidden identity under “Mind Else” with no profile information. There’s nothing to hide on here, we’re all here to help.