# Carb Ratio: How to Truly Optimize Your Carbohydrate Intake During Training

> What carb ratio means - and how to combine glucose and fructose for optimal results.

In endurance sports, carbohydrates are the primary source of energy, but optimal intake is more complex than quantity alone. What matters is the ratio of different carbohydrate forms in order to make efficient use of the body's maximum absorption capacity. Getting the dosage wrong can impair performance and cause gastrointestinal problems.

## The Importance of Glucose and Fructose

Carbohydrates are absorbed in the intestine via specific transporters. **Glucose** and **maltodextrin** use the SGLT1 transporter, whose capacity is limited to about 60 grams per hour. Exceeding this amount means undigested carbohydrates remain in the gut. **Fructose**, on the other hand, is absorbed via a separate transporter (GLUT5). By combining glucose and fructose, both transport systems can be used simultaneously, raising total absorption to as much as 90 grams of carbohydrates per hour.

## The Optimal Carb Ratio for Endurance Sports

The most scientifically studied ratio for carbohydrate intake is **2:1 (glucose to fructose)**. Studies show that this ratio can improve athletic performance by 8-13 % during efforts lasting over 90 minutes compared to glucose alone. While newer research is also examining ratios such as 1:0.8 for very high intake amounts (up to 120 g/h), the 2:1 ratio remains the pragmatic standard for most endurance athletes.

## Putting Carbohydrate Intake Into Practice

The amount of carbohydrates you need depends heavily on the duration and intensity of your activity. For efforts under 60 minutes, additional carbohydrates are generally unnecessary. For moderate intensity lasting 60-90 minutes, 30-40 g per hour is recommended, while for high intensity in that time frame, 60 g per hour with a 2:1 ratio makes sense. For intense sessions over 90 minutes, 60-90 g per hour with a **2:1 carb ratio** is essential to maintain performance.

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## Frequently Asked Questions

**What does a 2:1 carb ratio mean?**
A 2:1 carb ratio describes the proportion of two parts glucose (or maltodextrin) to one part fructose. This ratio enables maximum carbohydrate absorption per hour because it uses different transport systems in the gut.

**How many carbohydrates do I need per hour during sport?**
The amount varies depending on the duration and intensity of the effort. For longer or more intense sessions, between 30 and 90 grams of carbohydrates per hour may be necessary, with the 2:1 ratio becoming crucial at amounts above 60 grams per hour.

**Is gut training necessary for high carbohydrate intake?**
Yes, targeted gut training is essential to absorb high amounts of carbohydrates during sport without gastrointestinal problems. It increases transporter density and improves absorption capacity over a period of 4-8 weeks.

## Sources

Jeukendrup AE (2010), Sports Medicine - Carbohydrate and exercise performance.
Currell K & Jeukendrup AE (2008), Medicine & Science in Sports & Exercise - Superior endurance performance with ingestion of multiple transportable carbohydrates.
van Loon LJC et al. (2000), Journal of Applied Physiology - The effects of ingesting different amounts of carbohydrate on nutrient oxidation during prolonged exercise.

*WOO® Fast Endurance in the NEMAPO Shop.*