Race-day gut issues followed Marie Stevenson through 8 years of triathlon, and she’s a family doctor. So how did she race the IRONMAN 70.3 World Championship in Nice without them?

Marie is a family doctor from Calgary, Canada, who has been racing triathlon for 17 years. She thought her nutrition was great, yet for 8 of those years she planned every run around where the portaloos were. She shares what she used to eat on race day, the everyday fuelling gap she had no idea she was carrying and the 3 changes she credits for her first race without gut issues in 8 years. She also explains how she rebuilt her carb load in a foreign country when the bag holding her race food was stuck in Amsterdam during race week.

WHAT YOU’LL LEARN

• What Marie ate on race day for years, and why it kept letting her down
• What 8 years of trial and error did and didn’t fix
• The daily fuelling gap hiding behind a diet she believed was great
• How she rebuilt her carb load when her race bag went missing before 70.3 Worlds
• The 3 changes she credits for racing Nice with no gut issues
• Why it’s never too late for a masters athlete to change how they fuel

TIMESTAMPS:

01:22 From marathon runner to reluctant triathlete

06:14 Her race nutrition before TNA

07:30 8 years of race-day gut issues

10:54 Why a doctor finally fixed her fuelling

12:31 The daily fuelling gap she missed

16:03 Carb loading properly for the first time

18:25 Fuelling a 1,500km cycling trip

20:57 Race week chaos at 70.3 Worlds

29:51 What fixed her gut in Nice

32:34 Better sleep and changes for her patients

34:59 Advice for masters triathletes

ABOUT MARIE

Dr Marie Stevenson is a family doctor from Calgary, Canada, and a Triathlon Nutrition Academy athlete. She took up running at 47, has run 30 marathons and qualified for the Boston Marathon along the way. She has been racing triathlon for 17 years and finished 12th in the 65 to 69 age group at the 2026 IRONMAN 70.3 World Championship in Nice, France.

RESOURCES MENTIONED

• Ep 259: How 5 Masters Triathletes Fuelled the Hilliest 70.3 in the World

FUELLING THAT HOLDS UP WHEN RACE WEEK FALLS APART

Marie’s fuelling held up in Nice because she understood why her plan worked, which meant she could rebuild it on the fly. That’s what I teach inside the Triathlon Nutrition Academy, my education program where you learn how to fuel properly for training, racing and the rest of your life. Register your interest for the next cohort

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