What is a Functional Dietitian Nutritionist?

What is a Functional Dietitian Nutritionist?

A “functional dietitian nutritionist” is a term describing a holistic-minded registered dietitian-nutritionist (RDN) who helps people identify and address the root causes of chronic, long-standing health issues. We do this through a combination of clinical expertise, cutting-edge lab testing, nutritional counseling, and a “food as medicine” approach.

The primary goal and role of a functional dietitian nutritionist is to help people crack their unique health code and overcome unwanted chronic symptoms and conditions through leveraging the healing powers of food, herbs, lifestyle changes, and nutraceutical supplements as needed.

In this post you’ll learn what it takes to become a functional dietitian nutritionist, what we do, the benefits of an evidence-based “food as medicine” path, and how to get started working with or becoming a functional dietitian nutritionist.

But first, it’s important to clarity that while all functional dietitians are also nutritionists, not all functional nutritionists are dietitians!

Affiliate disclosure:  This post contains affiliate links* for programs that I love and have enrolled in, as a functional nutrition healthcare provider.  If you enroll in any programs through my affiliate links, I may make a commission at no extra cost to you!

Dietitians vs nutritionists – how are they different?

Technically all dietitians are also considered nutritionists, but not all nutritionists are dietitians.

What is a dietitian?

A dietitian is a board-certified nutrition professional who has completed a bachelor’s degree in nutritional sciences, plus over 1200 hours of accredited, supervised dietetic internship practicum work.  In order to become a dietitian and obtain the “RDN” credential, we also must pass a national board exam.

In order to maintain the RDN credential, all dietitians must complete and submit a minimum of 75 hours of “continuing education units” (CEUs) logged every five years. This allows us to stay up-to-date on the latest evidence-based research and trends in the nutrition and health field, so we can best serve our clients and communities.

  • According to the Commission on Dietetic Registration (CDR), as of January 2024, the minimum degree requirement to become a registered dietitian will change from a bachelor’s degree to a master’s degree.

Keep in mind that not all dietitians are “functional dietitians” – but first, let’s talk about what it means to be a nutritionist.

What is a nutritionist?

The term “nutritionist” refers to anyone who studies or practices in the field of nutrition.

There are no formal regulations or licensure requirements for someone to call themselves a nutritionist, although most nutritionists do receive some form of training and education, either formally or informally.

This doesn’t mean that nutritionists can’t help you – but it’s important to do your research before working with anyone who is going to be giving you advice about what to put in your body! 😉

I actually worked with a holistic nutritionist when I was already a registered dietitian, because I was suffering from leaky gut and irritable bowel syndrome (IBS) but didn’t know how to navigate this stuff from a holistic standpoint at the time. (I hadn’t yet received formal training in functional nutrition or gut health.)

  • I worked with my holistic nutritionist for over a year.  I benefited a great deal from our time together!

What is functional nutrition?

Functional nutrition is a branch of nutrition which stems from the fields of functional and integrative medicine.

How is it different from functional medicine?

Most people aren’t aware that functional nutrition and functional medicine actually overlap by ~90%!

This is because a functional approach to health is all about  “food as medicine” and a root-cause approach.

  • For example, the majority of functional dietitian nutritionists and functional medicine doctors will do functional nutrition lab testing and encourage our clients to make dietary and lifestyle modification based on what we uncover about their body.

But unlike conventional medicine which relies heavily on pharmaceuticals, functional medicine (like functional nutrition) leans mostly towards functional foods, nutraceuticals, and herbal supplements.  All of this is within our scope of practice as dietitians.

How is functional nutrition different from general nutrition?

Functional nutrition is unique in that it is holistic, with an emphasis on dietary recommendations that will allow people to restore wholeness and live more optimally.

General nutrition is often more focused on managing symptoms, counting macros, achieving a certain physical appearance, or a number on the scale.

Functional nutrition vs clinical nutrition

In clinical nutrition, the main purpose of dietary interventions is to help people to be more clinically stable.

It’s all about the short-term (“acute”) situation, without much thought given to long-term health outcomes.

  • For example, in mainstream healthcare settings, patients with diabetes are offered and encouraged to consume a wide range of sugar-free desserts sweetened with chemicals like Splenda or aspartame.
    • These artificial sweeteners don’t raise blood sugar acutely, but they’ve been shown to negatively impact gut bacteria, increase sugar cravings, and amplify insulin resistance in long-term studies (1).
    • Gut health, sugar cravings and insulin resistance are all factors well known to contribute to and amplify diabetes at the root-cause level.

In functional nutrition, our mission is to help people make food choices that will move them away from a state of chronic illness over the long-term.

A functional dietitian nutritionist will discourage you from consuming artificial sweeteners, because they can amplify or worsen your underlying chronic health condition at the root level.

Jenna Volpe Functional Dietitian NutritionistWhat does a functional dietitian nutritionist do?

Functional dietitian nutritionists and functional medicine practitioners look far just acute symptom management or clinical stability!

We bridge the gaps between clinical and holistic health, by combining our clinical knowledge and expertise with evidence-based training in herbal medicine, functional foods, nutraceuticals, and cutting-edge lab testing.

A holistic, multi-dimensional, root-cause approach

We dig deep, think critically, and read between the lines to see the full picture of our clients’ health from a holistic, birds-eye lens.

“Leave no stone unturned until you feel realigned!”

–Jenna Volpe, RDN, LD, CLT

In the Integrative and Functional Nutrition Academy (IFNA), we are taught the “STAIN” root cause acronym which stands for:

  • Stress
  • Toxins (heavy metals, mycotoxins, etc.)
  • Adverse food reactions (food allergies, sensitivities, and/or intolerances)
  • Infections (dysbiosis, mold, fungal overgrowth, etc.)
  • Nutritional imbalances

These are the 5 primary categories of underlying root causes which may culminate and lead to leaky gut, and potentially many other symptoms of chronic illness if left unchecked.

Focused on optimal long-term health outcomes

A functional dietitian and/or functional nutritionist will assess what needs to happen from a nutrition standpoint to move you completely away from a state of dis-ease, towards a state of balance, harmony and wellbeing of mind, body and spirit.

Customized and bio-individual

In functional and holistic nutrition, there’s an emphasis on biochemical individuality.

In other words, we believe that no two people are the same, so every client will likely get their own unique customized nutrition plan and supplement protocols based on a variety of factors.


You’ll notice that pretty much all types of functional dietitians, functional nutritionists, functional medicine practitioners, and holistic health professionals seem to specialize in gut health.

That’s not a coincidence! 😉

The gut is a major gateway into most all other aspects of health and wellbeing.

If you can optimize your gut health, pretty much every other facet of your health and quality of life will potentially improve to a certain degree.

“All disease begins in the gut.”


Related article:  What is a Gut Health Dietitian Nutritionist?

Functional nutrition testing

As a functional dietitian nutritionist, I’ve got access to HUNDREDS of cutting-edge functional nutrition and functional medicine lab tests.  This type of testing allows me to understand what’s going with my clients, on from a root-cause standpoint.

I’m also extensively trained(via continuing education) on how to interpret these tests, so that my clients will get the most out of our meetings.

(Functional nutrition testing is only as good as the ability of the practitioner to understand and interpret the results, and the client’s ability to execute the recommendations made based on what was revealed!)

Functional nutrition tests allow functional dietitians to provide exceptionally customized recommendations and individualized guidance around nutrition, supplements, and lifestyle habits to encourage and support natural healing over time.

Some of the most common functional nutrition lab tests we may run can include GI Mapping, DUTCH testing, micronutrient testing, the Mediator Release food sensitivity test, genetic testing, heavy metal tests, and more.

What does a functional dietitian nutritionist doAdditional services offered by functional dietitians / functional nutritionists

Aside from ordering functional nutrition lab tests, functional dietitian nutritionists are also qualified to provides clients with the following types of support:

  • Clinical nutrition assessment
  • Medical nutrition therapy recommendations
  • Herbal medicine recommendations
  • Holistic health coaching (with emphasis on foundational lifestyle changes)
  • Nutritional counseling/motivational interviewing
  • …and more!

If you’re a functional dietitian who would prefer NOT to work with patients/clients in a clinical setting, you can also share your expertise in different ways, such as:

  • Provide consulting services or teach other providers at a functional nutrition lab (such as Genova Diagnostics, Diagnostic Solutions, Mosaic Diagnostics, Precision Point Diagnostics, Vibrant America, SpectraCell, or Microbiome Labs)
  • Offer continuing education for other dietitians interested in learning about functional nutrition
  • Start a blog* and make passive income via display ads/affiliate promotions
  • Start a YouTube channel and make passive income via ads/affiliate promotions
  • Start a podcast
  • Self-publish low content books*
  • Create and launch a supplement product line
  • Create and launch online courses
  • …and more! (The sky’s the limit)

Areas of expertise

In functional nutrition, we believe that the mind, body and spirit are connected.

That being said, it’s hard to specialize in one niche without another!

Most often, functional dietitians tend to specialize in the following areas of focus:

  • Digestive health
  • Autoimmunity
  • Hormones (the thyroid, endocrine system, and reproductive system)
  • Mental health and the nervous system
  • The adrenals
  • Cardiometabolic health
  • Nutrigenomics

How to become a functional dietitian nutritionist

In order to become a functional dietitian nutritionist, the first step is to become a registered dietitian!

This entails getting a degree in nutritional sciences, followed by applying for and completing an accredited dietetic internship and sitting for the board exam.  This entire process can take anywhere from three to five years or longer.

For those who are already registered dietitians, the next step to becoming a functional dietitian nutritionist is to gain continuing education and experience in the field of functional nutrition/functional medicine!

Work for a functional nutrition / functional medicine clinic

You may want to consider applying to work for a functional nutrition or functional medicine clinic near you or virtually.

Get continuing education

As registered dietitian nutritionists, we’re required to complete at least 75 hours of continuing education every 5 years.  (This is not the case for a “functional nutritionist”, since the term nutritionist is generally less regulated.)

While this list is by no means exhaustive, below are some wonderful ways to get stated meeting (or maybe even exceeding) the continuing education requirements while immersing yourself in the world of functional nutrition:

Foundational training programs

Building a foundation in functional nutrition is a game-changer.  Starting here will help you to see the bigger picture (“the forest”), so you don’t just get lost in the trees or stuck in the weeds, navigating client cases.

(Otherwise, the other one-off trainings may feel piece-meal and/or overwhelming.)

Below are various programs to consider as a starting point. I recommend beginning with at least ONE of the following:

  • Institute for Functional Medicine (IFM) offers a variety of free starter courses if you’d like a glimpse into the world of functional medicine.  There are even some continuing education opportunities available for licensed healthcare providers, which is a nice perk!  They also have a variety of paid trainings. conferences, and certifications available for those who would like to go deeper.
  • Integrative and Functional Nutrition Academy (IFNA).  I love this program because it caters specifically to nutrition professionals.  There are 5 self-study tracks offered via IFNA (I’m currently working my way through all of them!).  I recommend completing at least the first 2-3 tracks  (at your own pace) to establish a solid functional nutrition foundation.  The trainings are expensive, but definitely worth their weight in gold!  If you complete all 5 tracks within 2 years or less, and you’re a licensed healthcare provider, you may qualify for their IFNCP credential (see below).
  • On-Ramp for GI Dietitians Roadmap* (This is a 4-week self-study introductory course with a focus on functional nutrition for gut health. It can be a nice way to dip your toes into the waters of functional nutrition for gut health specifically!)
  • Women’s Functional & Integrative Medicine Professional Training Program.​ (I have not taken this course, but it’s been recommended by several of my colleagues if you’d like to specialize in women’s health.)

Certification programs


These are great ways to stay connected with functional nutrition/functional medicine colleagues and community.  There are opportunities for live calls, special trainings, and case study level support.

Online courses

  • GI Dietitians Roadmap*  (This program was a complete game-changer for my gut health nutrition practice!)
  • SIBO Academy Bundle* (SIBO is an acronym which stands for “small intestinal bacterial overgrowth”.  It’s a growing issue in the gut health field, so if you’re thinking of becoming a gut health dietitian/nutritionist, getting SIBO-informed as a functional nutrition expert is not optional in my opinion!)
  • Kharrazian Institute (I have not yet taken any of the Kharrazian Institute programs but it hasa been recommended by some of my functional nutrition mentors and colleagues.)

Functional nutrition lab webinars

These are very informative and they’re FREE! But I find they will make more sense if you already have a functional nutrition foundation established, via one of the above programs.

(For the record, you don’t need to be a registered dietitian to take these courses. These resources are phenomenal can still help you to be a functional nutritionist! But if you aren’t credentialed as a healthcare provider, you may be limited in terms of how much you can do with 1-1 clients.)

The functional nutrition credential:  IFNCP

IFNCP is an accredited credential which stands for “Integrative and Functional Nutrition Certified Practitioner”.

If you’re a licensed healthcare professional, you can obtain this credential via the Integrative and Functional Nutrition Academy (IFNA).

You don’t need to be a registered dietitian in order to obtain this credential, but you must be a formally trained and licensed healthcare professional such as a Nurse Practitioner (NP), Medical Doctor (MD), Registered Nurse (RN), Naturopathic Doctor (ND), etc.

While you don’t need to have this credential in order to be a functional dietitian, it’s something that, by default, will provide you with a great deal of education and expertise in a relatively short amount of time.

The downside is that it can get very expensive.  Many of us are paying off other expenses related to private practice and business coaching (or life in general, for that matter).  It adds up fast!

Related articles & recommended reading


A functional dietitian nutritionist is a fusion between a registered dietitian and a holistic nutritionist.

We are highly trained from a clinical nutrition standpoint as well as from a holistic, integrative, functional medicine perspective so that our clients and community can get the best of both worlds.

Working with a functional dietitian nutritionist is a fabulous way to address and resolve your unwanted symptoms of chronic illness head-on, especially when related to gut health. Going this path will likely save you many years of suffering and frustration.

Book a 1-1 strategy call with me here if you’d like to chat about next steps in your career path as a functional RDN!