I’m Dr. Nanci Guest, in private practice since 1996 (formerly Power Play: Nutrition, Fitness, Performance) in the health & fitness industry. I am a Researcher, Registered Dietitian, Personal Trainer & NSCA Certified Strength and Conditioning Coach. I completed my PhD in Nutritional Sciences at the University of Toronto, where I researched “Nutrigenomics & Athletic Performance” with a particular interest in caffeine response & genetic variation (more papers coming from this data 2020). I offer this type of Genetic Testing for Personalized Nutrition (Plant-Based reports available) to athletes & the general public.

I also specialize in advanced sports nutrition as an international consultant. I help athletes who follow dietary patterns that include omnivorous, plant-based & vegan. I am currently researching high performance athletes & their unique genetic response to dietary nutrients & supplements based on their genotype (DNA) in my post-doc at UofT. My research will also look at associations of performance and body type to sport/muscle function genes in this athletic population.

In addition to research, I run a private practice with a variety of fitness/nutrition services. I serve athletes of all ages & levels as well as healthy individuals in the general population. Check out my outdoor bootcamp in Leaside!

Genetic Testing

The Nutrigenomix-Sport genetic test is now available. My goal is to help athletes reach their genetic potential by aligning their diet to their DNA.
Details at
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Dr. Nanci S. Guest is your expert in personal training for all ages and fitness levels, performance conditioning for athletes at all levels, and nutritional consulting all ages/sports in Toronto, Ontario.
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Nutrition Consulting

Nutritional consulting, dietary analyses, seminars and grocery store tours offered to individuals, families, team mates, school/sport team groups and more. Dietitian health benefits/coverage applicable to all services.
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What’s New

My First Book!

Honored to be the “Sport Nutrition Expert” in…

March 2018

Published PAP online Med Sci Sport Exerc (in press, August 2018)

As seen in the New York Times March 21, 2018.

Read Abstract at:

Caffeine, CYP1A2 genotype and endurance performance in athletes

Nutrition • Training • Genetics

Toronto: 416.873.3312  |  Vancouver: 604.818.8348

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