Jennifer O'Donnell-Giles MS RDN CSSD

Board Certified Sports Dietitian, Speaker, Writer, Exercise Physiologist, Triathlon Coach and RRCA Running Coach 


Jennifer has 24 years of  experience working with athletes in all sports and of all ages. She thrives on helping athletes achieve their goals!

Jennifer also has myriad of consulting experience from corporate wellness (GE, Pfizer, Meryl Lynch, Alan and Co.), to Clinical Hospital(Greenwich Hospital, Stamford Hospital, Columbia Presbyterian Hospital, LIJ-North Shore), Community Fitness (YMCA, and personal training facilities). Jennifer works with all athletes of all levels and abilities. 

She sits on the USOC (United States Olympic Committee) dietitian registry and works with Olympic hopefuls, NCAA Student-Athletes, Prep School Athletes, Adult Athletes and Youth Athletes.    Jennifer also writes for publications, speaks to teams, and consults with schools and recreation facilities. She is an author, and a freelance writer and also a faculty member of

Jennifer is also an adjunct Professor of Sports Nutrition at Columbia University -her Alma Mater.

Jennifer’s background is unique in that she was a youth athlete (swimmer and softball player) turned adult athlete (runner, open water swimmer and triathlete) who married an athlete (runner and triathlete) and is now the mother of four little athletes (Swimmers, hockey players and lacrosse players). In other words she knows the expectations of all moving parts for athletics - coaches, parents, sports organizations as well as athletes’ own expectations.


Fun Facts

Jennifer’s sports career has included being A Rev3 Triathlon Ambassador, A Base Performance Sponsored Athlete, A Member of the PowerBar Advisory Board, The Sports Nutrition Expert for NutriBullet, A Blogger for,,, and Appetite 4Health. She authored 3 books for MySportsRD (Nutrition for Swimmers, Nutrition for Lacrosse Players and Hydration for all Athletes), and author and editor for CanFitPro Certification program.

Jennifer is a multiple Ironman Finisher, Multiple Marathon finisher (including the Boston Marathon),  A three time All American Triathlete, and represented the USA three consecutive years at ITU (International Triathlon Union) World Championships competitor.


"I am a 59 year old endurance athlete who has been competing in triathlon for 7 years. I have had the extreme pleasure of working with Jennifer Giles as my coach and nutritionist throughout my triathlon career. When competing in triathlon, nutrition is the key to having a good race. Jenn was spot on for everyone of my races. For each race, Jenn put together a detailed plan for each one of my disciplines, telling me when and what to eat. I also received pre and post race nutrition plans that were crucial to preparing for my race as well as properly recovering from each race. I am pleased to say that I felt strong and still had “plenty of fuel in the tank” every time I crossed the finish line. I highly recommend Jenn Giles as a sport’s nutritionist and coach."

- Lisa Sperry

"Coach Jenn is amazing! She started me out on my triathlon journey when I was only 10 years old and has always been so incredibly supportive of me. Being a para-athlete and having different challenges than other athletes, has made my journey a bit harder. But Coach Jenn always thought of alternative ways of training, always encouraging me to believe in myself and to never give give up!"

Brittney Wheeler, 17 years old

"Jenn is exceptional! She is the best of the best when it comes to personalized training, nutrition, and increasing your physical and mental endurance. I started training with Jenn, not having an athletic bone in my body. Her patience, knowledge, and support was pivotal in helping me train for and finish several distance triathlons, including a half Ironman distance (70.3 mile) triathlon. Jenn's expertise helped me to fuel and train appropriately, as well as recover from racing and training without injury. Jenn has helped me to accomplish what I thought were impossible goals. She is the absolute BEST!!!"

Lisa Wheeler,

"12 years ago Jenn started me on the road to health. She taught me how to fuel my body and move my body. I now fuel my body so that I can swim, bike run and I have the power to lift weights! I haven’t looked back. She has been there every, stroke, rotation, stride and rep with sound nutritional advice. She believed in me and changed my life."

-Sheila Elser

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