Dr Tallis Barker
Extended Water Fasting Specialist · Registered Nutritional Therapist · Registered Associate Naturopath
Dr Tallis Barker, D.Phil., NT.Dip., Nat.Dip. is a specialist in extended water fasting, based in the UK and working internationally with clients worldwide. He is a registered Nutritional Therapist with the Federation of Nutritional Therapy Practitioners and a registered Associate Naturopath with the Society of Naturopaths. His professional practice is fully insured through Balens Specialist Insurance.
Over more than a decade, Tallis has worked with over 1,000 clients internationally, supporting water fasts ranging from 3 to 40 days, including longer fasts and people coming to fasting with complex or long-standing health concerns.
His particular interest lies where fasting becomes more complex: prolonged fasting, individual responses during the fast, careful refeeding, and the relationship between fasting and longer-term nutrition. His work combines extensive practical experience with professional training in nutritional therapy and naturopathy, published case research, teaching, and more than fifteen years of his own fasting practice.
Research, Teaching & Professional Work
Alongside his work with clients, Tallis writes, teaches and speaks about extended fasting.
He has presented at international health events including The Real Truth About Health, where his 2025 lecture focused on the role of extended fasting in chronic illness. The full lecture can be viewed here.
His published work includes two extended-fasting case reports:
• Long Covid: A Full and Permanent Resolution of Long COVID Symptoms achieved through an Extended Hybrid Water Fast: a Case Report, published in the Journal of Traditional Medicine and Clinical Naturopathy. Read the article.
• SIBO / gut dysbiosis: The full healing of SIBO (gut dysbiosis) achieved through an extended water fast: A case report, published in the Journal of Preventive Medicine and Holistic Health. Read the article.
Tallis has also lectured for the School of Health in the UK and is regularly invited to speak, consult and contribute to discussions on longer-term fasting.
His clients have included people fasting for general health reasons, those living with long-standing health problems, and health professionals seeking experienced support with extended fasting.
Academic Background & Training
Tallis’s route into health and fasting was far from conventional. He first trained as a musicologist, studying at Harvard University, where he graduated magna cum laude, before completing his D.Phil. at Oxford University. He remained at Oxford for several years afterwards, teaching and continuing his academic work.
In his forties, his interests began to move increasingly towards health, the body and fasting. What started as a personal exploration gradually became a new professional direction.
He went on to retrain at the School of Health in Stroud, UK, completing diplomas in Naturopathy (Nat.Dip.) and Nutritional Therapy (NT.Dip.), including work under Mary Sharma, ND. That later training did not replace his earlier academic background so much as take it in a very different direction: combining a habit of close inquiry with a much more experiential understanding of health and fasting.
Fasting as Lived Practice
Fasting has been part of Tallis’s own life for more than fifteen years.
In 2016, he undertook his first 21-day water fast and documented the experience in a detailed day-by-day journal, which remains one of the longest-running personal resources on this website. In 2025, he completed a 30-day water fast, again documenting the process and reflecting on how his experience of prolonged fasting had changed after nearly a decade of working with clients.
He continues to fast regularly himself, typically devoting around a month each year to fasting practice. His personal experience has included both water fasting and periods of dry fasting.
This lived experience is not a substitute for professional training or individual assessment, but it has given him a detailed understanding of what prolonged fasting can feel like physically, mentally and emotionally — from the inside as well as from the coaching chair.
Beyond Fasting
Tallis’s interests have always extended well beyond fasting and nutrition.
He is an avid long-distance trail runner and has become increasingly interested in the parallels between prolonged fasting and endurance sport. Both involve adaptation to fat-based metabolism, but for Tallis the connection is also psychological: each demands a particular mixture of discipline, patience and surrender.
He is also a classical pianist, with recordings available on Spotify and Apple Music, and the author of Growing into Being, a book exploring personal growth, philosophy and lived experience.
Tallis also hosts The Fasting Mind, a podcast devoted to the mental, emotional and philosophical dimensions of fasting.
PERSONAL EXPERIENCE
Personal Fasting Journals
My 30-Day Water Fast — 2025
In 2025, Tallis documented a 30-day water fast, reflecting not only on the physical experience but on how prolonged fasting had changed for him after many years of practice.
My 21-Day Water Fast — 2016
Tallis’s first 21-day water fast was documented day by day in 2016. The complete journal remains available as an unusually detailed record of his early experience with prolonged fasting.
Fasting Guides & Resources
Tallis has also created downloadable fasting guides and self-directed resources for people looking for practical support with preparation, shorter fasts and refeeding.
Check out the webshop on waterfasting.org
The webshop offers downloadable fasting plans and guides to help make your water fast a success.
