How Do I Go About This New "Job" Opportunity?

You need a business license.
And you'd need a waiver of liability of some sort. So that, you are not liable for any unforeseen things, like someone having an allergic reaction to something you told them to buy and eat.
And, you are not "officially" a Nutritionist. With a certificate or license of any sort. And you are a freelancer.

Do you have a disclaimer on your blog? Saying you are not a professional Nutritionist and this is just your opinions???

Or, you could work at Whole Foods. The employees in the supplement department for example, are very knowledgeable and have training. Per the company.

To me, a "Health Coach" and a "Food Shopper" and a "Nutritionist" are all very different things and requirements.
You need to, narrow down, WHAT exactly, you will do. And then research, the qualifications you need, and the laws of it.

The thing is, you do this now as a "hobby." It is something you like etc. But to make it a business and then have people pay you for your services, makes it a whole other, realm. You need professional qualifications etc. and business licenses, and liability forms/insurance etc.
Or, you could just be a person's "personal shopper." Like how some clothing department stores, have, "Personal Shoppers" to help them put together a wardrobe.
But with "food" things, well, there are more ramifications... such as a person's health status, their allergies etc. and their lifestyle dietary requirements etc. And, you are not a Doctor.
Or you just teach people how to shop and read labels.
But you need to research, the legalities of it and the requirements for such a role.
And consult with an Attorney.

LOL I think S. is an attorney (S.H.). :P

How about calling yourself a "Lifestyle Consultant"? That doesn't imply medical knowledge, and you can just share with people your worldview about how you shop/exercise/eat.

I'm not sure if I'd pursue another degree per se, unless there was some clear benefit to doing so.

I agree with the general waiver, and always refer people to their own physicians before they start doing things the way they do them.

I would research any licensing necessary, but I'd be surprised there would be licensing for something that generalized.

Good call on the taxes.

Let us know how it goes!

JMO.

ETA: I'd definitely look into forming an entity if you start spending time on this. And I agree with SH about researching the legalities of talking to people about food.

Talk to a lawyer,
talk to a lawyer, and then
talk to a lawyer!
It's a neat idea and sounds like you are following your passion but there are so many what-ifs with people's health and well-being and you don't want to accidentally hurt someone or lose the farm. What if the person is diabetic, has gerd, what about drug/food interactions, supplement/food interactions, add and adhd food issues, food allergies, etc.

I don't mean to be a debbie-downer. I just think you need to be totally protected before you begin.

Keep us posted and good luck!

business license
liability insurance
thorough tax receipts
& absolutely have a disclaimer.

But.....are these clients going to be in our neck of the woods or will you be traveling into St Louis/Jeff City? How will you factor the travel expenses into your fees? & how will you go about setting fees for such a unique niche in personal training?

In addition to your FB postings, I would also contact your local drs, gyms, & mental health facilities. They may be able to direct business your way! Also set up at local/area fundraisers, festivals, etc. .....get your face known! Oh, & what about doing presentations at PTO, daycares, & church groups? Good Luck! Hope you hit St James!