Questioning the Review That Suggests as Little as 10g/h of Carbohydrate Can Sustain Endurance Performance

A recent review by Noakes et al. has attracted significant attention for its suggestion that consuming low doses of carbohydrates (e.g., potentially as low as 10 grams per hour) is sufficient for maintaining performance during endurance exercise. More specifically, the authors argue that this intake is adequate to prevent exercise-induced hypoglycemia (EIH) and, in turn, sustain athletic output.

It is important to note that this publication is not a new experimental trial, but rather a review and synthesis of existing research. Its conclusions have gained considerable traction on social media, where they have recently been presented as a challenge to long-standing sports nutrition guidance.

But does this interpretation of the evidence truly overturn what decades of research and applied practice have shown about carbohydrate needs for endurance performance? We don’t believe it does. This article examines the review more closely and outlines why we believe its conclusions warrant a more critical reading.

EIH Matters – But It’s Not the Only Factor

A research review is only as useful as the question it sets out to answer, or more precisely, the hypothesis it seeks to evaluate. In the case of the Noakes et al. review, the authors frame endurance fatigue primarily through the lens of exercise-induced hypoglycemia (EIH), arguing that falling blood glucose triggers a protective, centrally mediated reduction in performance.

There is little dispute that blood glucose regulation matters. The role of hypoglycemia in limiting endurance performance has been recognized for decades and carbohydrate ingestion has long been used, at least in part, to stabilize blood glucose during prolonged exercise. In that sense, the review does not introduce a new concept. What it attempts to do, however, is reposition EIH as the dominant limiter of endurance performance, while downplaying the importance of other carbohydrate-related mechanisms, including – but not limited to – glycogen availability.

This is where we believe the argument becomes overly narrow.

We agree that EIH matters. But we do not agree that preventing hypoglycemia alone can fully explain the broad and consistent performance benefits observed with carbohydrate fueling across different athletes, intensities, and race formats.

What the Evidence Shows – and What the Pros Are Doing

A substantial body of high-quality research demonstrates a clear dose-response relationship between carbohydrate intake and endurance performance, with performance benefits consistently observed as intake increases into the 60-90g/h range. Across these studies, higher carbohydrate availability is associated with improved time trial outcomes, greater power output sustainability, and delayed fatigue.

Regardless of the precise mechanism, this evidence alone challenges the suggestion that intakes as low as 10-30g/h are broadly sufficient for endurance performance. In many of these trials, athletes are not experiencing overt exercise-induced hypoglycemia at lower intake levels, yet still perform better when carbohydrate availability is increased. This strongly suggests that carbohydrate’s role extends beyond the prevention of hypoglycemia alone.

The contrast becomes even more striking when we look at contemporary elite practice. Over the past several years, many of the world’s best endurance athletes have progressively increased carbohydrate intake during racing, with reported intakes now commonly reaching 90-120g/h and, in some cases, exceeding that range. Athletes and coaches frequently attribute these higher intakes to improvements in durability, late-race performance, and overall output at intensities previously difficult to sustain.

To be clear, there is currently limited experimental evidence specifically designed to validate ultra-high carbohydrate intakes at these levels.  But the absence of such evidence does not imply the absence of benefit. Rather, it highlights a familiar lag between applied practice and controlled research.

If anything, the widespread adoption of higher carbohydrate intakes among elite performers suggests that additional mechanisms – beyond hypoglycemia prevention – are contributing meaningfully to performance. At the professional level, where livelihoods depend on marginal performance gains, fueling strategies are rarely adopted casually. These athletes operate within highly resourced support systems, often alongside leading sports scientists and nutritionists, and their collective shift toward higher carbohydrate intake strongly suggests that such approaches confer real-world performance benefits, even as the scientific literature continues to refine its understanding of the underlying mechanisms.

Our Conclusions and Key Takeaways

The Noakes et al. review focuses attention on blood glucose regulation and EIH as meaningful constraints on endurance performance. Few would disagree that EIH matters, particularly during prolonged exercise. Where we part ways, however, is in how narrowly this mechanism is positioned to explain the full performance benefits of carbohydrate fueling.

Preventing hypoglycemia is clearly one function of carbohydrate intake, but is unlikely to be the only one. Decades of controlled research demonstrate performance improvements as carbohydrate intake increases. These findings, taken together with contemporary elite practice, suggest that carbohydrate availability influences endurance performance through multiple interacting pathways that are not yet fully captured.

Ultimately, the question is not whether endurance athletes can sustain performance on very low carbohydrate intakes under certain conditions. The more relevant question is whether such intakes represent an optimal strategy across the wide range of demands imposed by modern endurance racing. Based on the totality of evidence and applied experience, we remain unconvinced that they do.