Why We Use a 1:1 Glucose-to-Fructose Ratio

Carbohydrate fueling during endurance exercise has evolved dramatically over the last two decades. What started with simple sugars has progressed into sophisticated strategies designed to deliver more usable energy, more efficiently, for longer periods of time.

One of the most important advances in sports nutrition was the discovery that combining glucose and fructose allows athletes to absorb and use more carbohydrate per hour than glucose alone.

At Formula 369, our drink mix uses a 1:1 glucose-to-fructose ratio. This choice wasn’t made for marketing reasons. It’s rooted in how the human body absorbs carbohydrates and what the scientific literature shows is possible when both pathways are fully utilized.

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Why glucose and fructose work better together

Glucose and fructose are absorbed through separate intestinal transport systems:

• Glucose uses the SGLT1 transporter

• Fructose uses the GLUT5 transporter

When glucose is consumed on its own, absorption is limited by the capacity of SGLT1. This is why glucose-only fueling strategies plateau at around ~60 grams per hour.

Adding fructose activates a second transport pathway, allowing total carbohydrate absorption and oxidation to increase substantially. This principle—often referred to as multiple transportable carbohydrates—is the foundation of modern high-carbohydrate fueling.

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What the research shows about carbohydrate ratios

Over the years, researchers have studied different glucose-to-fructose ratios at progressively higher carbohydrate intakes.

Here’s the key progression:

• 2:1 glucose-to-fructose demonstrated that combining sugars significantly increases carbohydrate oxidation compared to glucose alone.

• Ratios closer to equal amounts of glucose and fructose showed even higher oxidation rates, indicating greater total carbohydrate availability.

• The highest exogenous carbohydrate oxidation rates ever measured occurred when glucose and fructose were consumed in equal amounts (1:1) at high intake levels.

In a landmark study, trained cyclists ingesting glucose and fructose in a 1:1 ratio achieved oxidation rates of approximately 1.75 g per minute, which remains the highest reported in the scientific literature.

This finding is important because it defines the upper physiological capacity for carbohydrate absorption during endurance exercise.

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Why the ceiling matters

The goal of endurance fueling isn’t simply to consume carbohydrates—it’s to deliver usable energy to working muscles.

Higher exogenous carbohydrate oxidation means:

• More fuel available during long or intense efforts

• Less reliance on limited glycogen stores

• Greater potential to sustain performance late in exercise

By fully engaging both intestinal transport pathways, a 1:1 glucose-to-fructose ratio represents the most complete use of the body’s carbohydrate absorption machinery.

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Why we chose 1:1

We chose a 1:1 glucose-to-fructose ratio because:

• It has produced the highest carbohydrate oxidation rates ever measured

• It fully utilizes both major intestinal carbohydrate transporters

• It represents the most advanced expression of multiple-transport carbohydrate fueling

• It aligns with the demands of modern endurance training and racing, where carbohydrate needs are higher than ever

Rather than designing around minimum requirements, we chose to design around maximum capacity.

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The big picture

Fueling strategies have evolved because endurance sport has evolved. Athletes are training harder, racing longer, and consuming more carbohydrate per hour than ever before.

A 1:1 glucose-to-fructose ratio reflects that evolution.

It isn’t about trends or shortcuts. It’s about using the best available science to deliver energy as efficiently as possible—so athletes can focus on the work, not the math.