Gut Training: Practice Your Fueling Before Race Day

Nutrition & Performance · Evidence Explainer · November 12, 2026

A fueling plan needs to work for your stomach as well as your schedule. Research on “gut training” gives endurance athletes a reason to rehearse—and a reason to keep expectations realistic.

What the early running trial found

In a 2017 randomized study, 25 endurance runners completed a demanding laboratory challenge: two hours of running while consuming carbohydrate, followed by a one-hour distance test. They then spent two weeks practicing with carbohydrate gel-discs, carbohydrate food or a placebo before repeating the challenge.

Gastrointestinal symptoms fell by about 60% in both carbohydrate groups, with greater reductions than in the placebo group. Distance-test performance improved by 5.2% with gel-discs and 4.3% with food; the placebo group declined by 2.1%.

Those results are encouraging, but they came from a small, short experiment. The test supplied 30 grams of carbohydrate every 20 minutes—90 grams per hour. That was a research protocol, not a starting prescription for every runner. We reviewed this study’s abstract, rather than its full text.

A later study complicates the picture

A 2022 paper examined a 14-day strategy combining a very high carbohydrate diet, gut practice and other fueling measures in two training-camp studies. One included 19 elite male racewalkers. The other involved 16 highly trained runners, contributing 18 datasets because two participated in both diet conditions at different camps.

The runners improved their finishing time trials similarly under the higher- and moderate-carbohydrate strategies. The higher-carbohydrate plan did not produce a clear additional performance advantage. Racewalkers experienced more gastrointestinal symptoms later in their exercise test under the higher-carbohydrate condition.

This was not a clean test of gut practice alone: several dietary changes were bundled together, and allocation was not randomized. Small groups and changes during training also complicate interpretation. The findings do not establish that gut training is useless; they show why tolerating more fuel and performing better should not be treated as interchangeable outcomes.

Rehearse the plan you intend to use

The Australian Institute of Sport’s sports-gel guidance recommends trying intended race products during training to assess tolerance. It also emphasizes appropriate fluid intake and gradual increases in carbohydrate volume or concentration when practicing.

A practical application is to keep a simple record of the product, amount, fluids, workout conditions and symptoms. That turns rehearsal into information you can discuss with a sports dietitian. It is an organizational suggestion, not a method tested by these two papers.

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