If you use endurance gel or carbohydrate drinks, you've probably noticed that many formulas use more than one type of carbohydrate: most commonly it's glucose (or maltodextrin) combined with fructose.

A 2:1 glucose-to-fructose ratio has been used across endurance nutrition products for years, but recently they seem to be moving toward a 1:0.8 ratio.

This shift is due to the variance in how the gut absorbs different carbohydrates and what happens when athletes start trying to consume higher amounts of fuel during prolonged exercise.

Why the combination?

In our article about how many carbs per hour you actually need, we discuss the way glucose and fructose use different transport pathways in the intestine. Glucose is primarily absorbed through a transporter called SGLT1, while fructose uses another transporter known as GLUT5.

When an athlete relies solely on glucose, the glucose transport pathway can become saturated, leading to a plateau in usability at around 60g per hour. Adding fructose gives the body access to a second intestinal transport pathway, which can increase the absorption and efficacy of use during exercise.

Research comparing glucose alone versus glucose-fructose combinations has consistently shown higher rates of breaking down and utilising carbs for energy when multiple transportable carbs are used. 

So where did the traditional 2:1 ratio come from?

A 2:1 ratio just means there are approximately two parts glucose to every one part fructose. eg. 60g of carbohydrate would contain roughly 40g glucose and 20g fructose.This ratio became common because early research showed that adding fructose to glucose could substantially increase carbohydrate oxidation compared with glucose alone.

A study in trained cyclists compared a glucose-only drink with a glucose-fructose drink supplied in a 2:1 ratio. Both provided carbohydrate at a high rate of 1.8g per minute, or around 108g per hour. The glucose-fructose condition resulted in better cycling time-trial performance than glucose alone. 

Hence, these studies told us 2:1 was a pretty successful ratio, and it showed that dual carb sources works better than relying on glucose alone. But is it the optimal ratio?

Let's discuss the 1:0.8 ratio.

A 1:0.8 glucose-to-fructose ratio contains proportionally more fructose than a traditional 2:1 blend.

At 90g carbohydrate per hour, for example:

Ratio (at 90g carbs / hr)	Glucose (g)	Fructose (g)
2:1	60g	30g
1:0.8	50g	40

While this difference may not seem significant, it does change how evenly the carbohydrate load is distributed between the two intestinal transport pathways. Rather than trying to push a large amount of glucose through a pathway that may already be approaching saturation, a 1:0.8 ratio makes greater use of fructose absorption as total carb intake rises.

A review examining glucose-fructose mixtures found that solutions containing fructose-to-glucose ratios between ~ 0.7:1 and 1:1 were absorbed particularly well. Within the studies reviewed, a ratio around 0.8:1 fructose to glucose performed favourably for endurance performance. 

Another study that directly compared several fructose-to-glucose ratios during cycling showed that the 0.8 ratio produced higher carbohydrate usability and moderately better sprint performance than the lower and higher fructose ratios tested. 

Is 1:0.8 better than 2:1 in all use-cases?

Like most things, the context dictates the ideal ratio required. The advantages of using dual carb sources become most relevant when carbohydrate intake is already reasonably high, particularly during prolonged endurance exercise.

If you are consuming 30g of carbohydrate per hour during a shorter session, the precise ratio of glucose-to-fructose is unlikely to be the main factor that make or break your performance. The argument for manipulating the ratio is strongest when athletes are consuming higher carbohydrate intakes, often above 60g per hour, and exercising for several hours.

The ratio is just one part of the fuelling plan: the total amount of carbohydrates, the duration of exercise, and what your gut can tolerate are also important factors to be considered alongside carb source ratio.

What about gut comfort?

This is a significant consideration, yet so often given lower importance. When carbohydrate stays in the intestine rather than being absorbed efficiently, it can cause bloating, cramping and nausea. Not what you want on race day, or any training session.

Using glucose and fructose together can increase carbohydrate absorption compared with supplying a very large amount of glucose through one pathway. Research has found that multiple transportable carbohydrates can reduce gastrointestinal distress compared with high-dose single-carbohydrate strategies in the endurance space.

However, a 1:0.8 ratio doesn't necessarily guarantee zero gut issues in every case. Experiencing these symptoms when you race can also be influenced by your total carbohydrate dose, concentration of the drink, fluid intake, exercise intensity, heat, individual fructose tolerance and whether or not you have practised the strategy in training.

A well-designed carbohydrate ratio does offer improved carb absorption, however, which supports lower risk of excess carbohydrates sitting in the gut causing these disruptive symptoms.

You still need to train your gut.

Changing carbohydrate ratios does not eliminate the importance of practising your fuelling strategy. If you currently tolerate 40g of carbohydrate per hour, switching to a 1:0.8 product does not mean you should suddenly jump to 90g or 120g per hour. Higher carbohydrate intakes should be built progressively through training so you can establish what your gut tolerates while exercising at the intensity you expect on race day.

An endurance supplement is only useful if you can consume it comfortably and effectively when you are two or three hours into an event.

We cover how to build that tolerance in our guide to gut training and working towards 90g of carbohydrate per hour →

References.

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5. Wilson PB. Multiple transportable carbohydrates during exercise: current limitations and directions for future research. Journal of Strength and Conditioning Research. 2015;29(7):2056–2070.
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7. Rowlands DS, Thorburn MS, Thorp RM, et al. Effect of graded fructose coingestion with maltodextrin on exogenous 14C-fructose and 13C-glucose oxidation efficiency and high-intensity cycling performance. Journal of Applied Physiology. 2013;115(10):1452–1460.
8. From Metabolism to Medals: Contemporary Perspectives and Revisiting Carbohydrate Guidelines for Fueling Endurance Athletes during Exercise. 2026.