What’s The Difference Between Nutritionists, Registered Dietitians, and Functional Medicine Practitioners?

General Health

written by:

Emily Hage, MS, RD

What’s the difference between nutritionists, registered dietitians, and functional medicine practitioners? Deciding who to work with to take control of your health can be challenging when you’re unclear about what the various credentials and titles mean. Understanding how they differ can help you choose the right practitioner to fit your needs. It’s important to look for specific certifications, academic training, experience in the field, and a proven track record of providing results.

In this article, we break down what distinguishes these titles from one another and provide a brief overview of the field of functional medicine. First, let’s explore the differences between a nutritionist and a registered dietitian, as these two titles are frequently mistaken as being synonymous.

Nutritionist vs. Registered Dietitian

While all dietitians are considered nutritionists, the reverse is not necessarily true. “Nutritionist” is an unregulated term and does not necessarily require any specific education or training. “Registered dietitian” is a legally regulated professional credential awarded to those who have completed specific education and training requirements and have passed a national certification exam. Dietitians are trained to diagnose nutrition conditions and provide medical nutrition therapy, whereas nutritionists may not be qualified to do so. As of 2024, a master’s degree will be required to become a registered dietitian. Similar to a registered dietitian, there is one other legally regulated nutrition degree, certified nutrition specialist (CNS), which requires a minimum of a master’s degree in nutrition or a related field.


“Nutritionist” is an unregulated term, and does not require any formal education or training; this means that someone using this title can be self-taught about nutrition. Nutritionists may or may not have taken online or in-person courses in nutrition. Without a certification or advanced degrees such as an RD or CNS, they are not necessarily licensed or qualified to prescribe supplements or medications, order labs, diagnose or treat nutrition-related conditions, or provide medical nutrition therapy. If you want to work with a qualified nutrition expert, it’s recommended to find an RD or CNS.

Registered Dietitian

Registered dietitians (RDs), also known as registered dietitian nutritionists (RDNs) are healthcare professionals with specialized training in nutrition, dietetics, and medical nutrition therapy who focus on using nutrition as a way to manage certain health conditions. The requirements to receive the RD/RDN credential per the criteria of the Academy of Nutrition and Dietetics in the U.S. include:

  • Completion of at least a bachelor’s degree (minimum of a master’s degree starting in 2024) and a collection of academic coursework accredited by the Accreditation Council for Education in Nutrition and Dietetics (ACEND) including courses such as chemistry, biology, anatomy and physiology, organic chemistry, microbiology, biochemistry, psychology, food science, clinical nutrition assessment and intervention, nutrition education and counseling, food production and management, community nutrition, research methods, and more
  • Completion of a 6-12 month ACEND-accredited dietetic internship program encompassing 1000+ hours of supervised practice including a clinical rotation at a healthcare facility
  • Successfully passing the national registration exam through the Commission on Dietetic Registration (CDR) 
  • Obtaining licensure, depending on the state(s) of practice
  • Completion of ongoing education requirements (CEUs) to maintain the RD/RDN credential and staying current in a constantly evolving field 
  • Optionally obtaining additional certifications in specialty areas such as oncology, renal nutrition, diabetes education, eating disorders, pediatrics, and sports dietetics

Most RD programs focus on clinical training for dietitians to work in hospital settings, providing support to medical teams in the treatment of acute and chronic illnesses and various disease states. However, many dietitians go on to work in a variety of settings and specialty areas (such as private practice nutrition counseling, research, food service management, education, public health, and corporate wellness programs) and/or seek out additional training in areas such as eating disorders, intuitive eating, and functional medicine nutrition therapy. It’s important to find an RD whose specialty meets your needs.

Similarly to registered dietitians, certified nutrition specialists are nutrition experts who take an evidence-based personalized approach to nutrition care and have met specific education, training, and examination requirements. Certified nutrition specialists must have an advanced degree in nutrition or another healthcare field, complete supervised practice hours, and pass an exam by the Board for Certification of Nutrition Specialists.

Functional Medicine Practitioner

Functional medicine is a systems-based patient-centered approach to healthcare that focuses on identifying and addressing the underlying causes of disease to help patients achieve optimal health. Functional medicine practitioners create comprehensive care plans encompassing the hallmarks of functional medicine, which typically include:

  1. Holistic, systems-oriented approach – The systems-based approach of functional medicine focuses on the interactions and connections between all body systems (including the digestive, hormonal, immune, and nervous systems), and how they may be influencing the development or persistence of chronic health issues. Rather than a focus on each individual organ system, functional medicine offers a holistic understanding of the interconnected nature of the body.
  2. Patient-centered, individualized care – Functional medicine is patient-centered rather than disease-centered. Functional medicine practitioners assess and treat patients by considering the whole person and all the factors that may be contributing to their current state of health and health concerns. This may include analyzing health history, physiology, nutrition, lifestyle, sleep, stress, genetics, and environmental factors. Patients are empowered to develop a deeper understanding of their body and overall health, and may take an active role in the creation of a customized treatment plan that suits their unique needs. 
  3. Identification and treatment of underlying causes – By addressing and treating the underlying causes of health issues–whether it’s stress, toxin exposure, food sensitivities, medication/antibiotic use, or another root cause–functional medicine seeks to identify, prevent, and treat issues and imbalances before they become diagnosable conditions.
  4. Optimal health and prevention-focused – Functional medicine practitioners aim to help patients achieve optimal health and vitality by focusing on the foundational aspects of wellbeing (nutrition, movement, sleep, stress, and physical/social environment). The goal is to optimize health and quality of life in the long term rather than only treat symptoms or problems in the short term.
  5. Comprehensive testing and multimodal treatment plans – Functional medicine combines the best cutting-edge testing and treatments with conventional medicine practices. Practitioners leverage data from patient health history, comprehensive laboratory testing (blood, stool, urine, saliva, and/or hair), and wearable tech devices to create personalized multimodal treatment plans. These interventions range from dietary changes, targeted therapeutic supplementation, lifestyle adjustments, and restorative mind-body techniques to improve the overall functioning of the body and restore balance in the body’s systems. Nutraceuticals and pharmaceutical treatments are incorporated when needed.
  6. Evidence-based – Functional medicine utilizes evidence-based research and treatment modalities from peer-reviewed studies and is on the cutting edge of science and medicine.

The growing demand for functional medicine has led to an increase in practitioners trained in this area, including those certified by organizations such as the Institute for Functional Medicine (IFM) and the Integrative and Functional Nutrition Academy (IFNA). Functional practitioners may also be registered dietitians, certified nutrition specialists, or hold other advanced degrees in nutrition, medicine, or another health-related field. To be eligible for these certifications, practitioners are typically required to have a graduate degree in a health-related field or at least a bachelor’s degree incorporating qualifying coursework. It’s important to note that there is currently no standardized certification process or governing body. Therefore, it’s crucial for individuals seeking functional medicine services to do their research on each practitioner’s education and experience. 

Nutritionists vs. RDs vs. Functional Medicine Practitioners – Final Thoughts:

We understand all too well how difficult it can be to find a practitioner that you trust with your healing process. It’s important to look into the credentials of any practitioner you’re considering working with and find someone with the scope of practice that fits your needs.

At Birchwell, you’re getting the best of both worlds by working with a practitioner who has an academic nutrition background and is also an expert in advanced and alternative treatment modalities. Yes, food is an integral part of our toolkit. However, we don’t subscribe to textbook diets – and recognize that sometimes food modifications alone are not enough. We combine functional and integrative nutrition advice with advanced testing to identify issues, incorporating supplements in therapeutic ways, and recommending specific lifestyle products and strategies. This is how we are able to heal the issues that a conventional dietitian or nutritionist cannot resolve, including digestive problems, hormonal imbalances, mood disorders, skin conditions, metabolic dysfunction, inflammation, autoimmunity and more. The improvements in our clients’ signs, symptoms and labs speak for themselves.


Feeling better is possible. Meet with one of our practitioners to find out if 1:1 Functional Medicine Consulting is right for you.

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Anya is a Registered Dietitian, Functional Medicine Practitioner and founder of Birchwell, a virtual integrative health clinic based in New York City.

She specializes in helping her clients identify the root cause of their health concerns through advanced lab testing and her comprehensive assessment. She uses functional diet, supplement, and lifestyle strategies to address any imbalances in the body. Through her integrative and functional nutrition practice, Anya has helped hundreds of adult women and men fix their gut health (e.g. SIBO, reflux, candida, etc.), balance their hormones (e.g. PCOS, peri-menopause, estrogen dominance, etc.), clear their acne or eczema, boost their energy and performance, combat anxiety and depression, improve their body composition, reduce their joint pain - and more.

Anya Rosen, MS, RD, LD, IFNCP, CPT

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