How to train your body to use more carbohydrates?

Most runners, cyclists, and triathletes limit themselves to 50-60g of carbohydrates per hour… for fear of bloating, reflux, nausea, or diarrhea. As a result: they lack fuel during long efforts and performance plateaus. However, the gut is not a fixed limit. It adapts remarkably when trained in a targeted manner.

This process, called “gut training,” increases the number and efficiency of intestinal transporters (SGLT1 for glucose, GLUT5 for fructose). It also improves gastric emptying and reduces malabsorption. Studies show that 4 to 8 weeks of practice are often enough to gain an additional 30 to 60 g/h of capacity, with far fewer gastrointestinal symptoms.

Here is the concrete and progressive protocol to follow:

1. Increase doses in progressive stages
   Start from your current tolerance (e.g., 50-60 g/h) and increase by 10-15 g/h every 1 to 2 weeks, only during long outings (≥ 90 min to 2 h). Realistic example: weeks 1-2 at 65 g/h → weeks 3-4 at 80 g/h → weeks 5-6 at 90-100 g/h. Adaptation takes 4 to 10 weeks maximum.
2. Choose multiple transportable and easily digestible carbohydrates
   Prioritize mixtures that use multiple absorption pathways (glucose + fructose in a 2:1 ratio or HBCD + fructose). Very low osmolality formulas such as Highly Branched Cyclic Dextrin (HBCD) are ideal during this training: they empty the stomach quickly and limit the feeling of heaviness even at high doses.
3. Simulate your race conditions and stay consistent
   Do these sessions at least 1 to 2 times a week, at the intensity and in the conditions (heat, duration) of your competition. Always combine carbohydrates with proper hydration and electrolytes. Keep a journal of your sensations to adjust quickly. Avoid changing everything on race day.

Classic mistakes not to make: increasing too abruptly, using only pure glucose in high doses, or doing gut training only during competition.

With this method, the majority of athletes go from "I can't tolerate anything beyond 60 g/h" to intakes that truly delay fatigue during marathons, long trails, or Ironmans.

In Elixyr, the 30% HBCD while respecting the 2:1 glucose:fructose ratio makes this training significantly more comfortable. The branched structure of HBCD allows you to load more carbohydrates without irritating your digestive system, thus accelerating your adaptation.