The 60/90/120 Debate: What is The Right Amount of Carbohydrate For Your Needs?

Endurance events are booming. Marathons, sportives, triathlons, adventure races. Every year, more of us are tackling new challenges. We’re all looking for ways to train smarter, feel stronger, and go longer. And we want to enjoy every minute and every mile. 

We’re after every edge we can get – and not just with our bike and our shoes. Suddenly, the science of fuelling is a big deal. And one debate dominates… Just how many carbs do we really need? And how does the quantity affect our performance?  

So, let’s take the very latest sports science and break it down into something practical that will help you in both training and competition.

Fuelling to Go the distance

Endurance performance isn’t just about fitness. It’s about how efficiently you can produce energy, how long you can hold your pace, and how well you resist fatigue.  

Let’s look at the four key factors: 

• VO₂max: the size of your aerobic engine
• threshold utilisation: how much of that engine’s capacity you can hold
• running/cycling economy: how much oxygen you burn at a given pace
• durability: how well you hold your form and efficiency as you tire

Carb availability influences all four. When carbs run low, everything gets harder: your oxygen cost rises, your pace drifts, and your ability to hold form drops.  

It’s all about the carbs

Your body typically stores roughly 400–500 g of carbs as glycogen. At long-distance pace, you burn through them quickly – anywhere between 1.5 and 3.5 g per minute. 

Once those stores get low, you’re forced to rely more on fat. It’s a great long‑game fuel, but it just can’t support race pace. That’s when you end up slowing down, losing rhythm, and facing that dreaded, wobbly sensation nobody wants to feel – ‘hitting the wall’. 

During endurance efforts, carbs take care of crucial functions: 

• keeping blood glucose steady
• maintaining high energy output
• delaying the shift to fat use
• reducing the risk of hitting the wall

The question isn’t whether you need carbs. It’s how many?

The new frontier: carbs per hour

Endurance nutrition has evolved fast. The upward trend has been dramatic. Just how many carbs can we (1) handle and (2) use?  

For a long time, nobody even thought about it. Then, through the ‘80s and ‘90s, 30–60 g per hour was the benchmark. More recently, 90 took over. Now, 120, and even higher, is shaping the future of endurance fuelling – not as a gimmick, but because the science supports it. 

This shift comes from a clearer understanding of how the gut and muscles work together during longer runs and rides. Carbs are still the best fuel for maintaining strong, sustained output. More of them is generally a good thing. But there’s more to it than just shovelling them in and hoping. 

Lifting the ceiling, lowering the times

What’s new is the recognition that our guts are trainable, and, with practice, most of us can tolerate and use far more carbs than we previously thought. 

This isn’t about chasing ever-increasing numbers for the sake of it. It’s about determining each athlete’s tolerable limit – the upper point where more fuel still means better performance. It’s an ambitious, individualised approach to endurance fuelling. And it’s in an exciting place. 

Elite runners and cyclists are now pushing 140–150 g per hour and beyond, volumes that would have been unthinkable even a decade ago. We’re seeing the impact in high-profile races. Check out Charles Hicks’ 2:04 in the Boston Marathon. It’s eye-opening stuff. 

Welcome to the new reality: fuelling is no longer a limiter to be managed – it’s a performance tool to be optimised.  

The science that’s changing the game

The landmark study of carb uptake redefines what’s possible. It was the first to directly compare 60, 90, and 120 g per hour in runners, not cyclists, which matters, because running places far greater stress on the gut.  

The results are decisive. As carb intake increases, so does exogenous carb oxidation, meaning athletes can actually use more of what they take in. At 120 g per hour, elite marathon runners can consistently maintain high carb use across a full race, rather than drifting towards fat use.  

It gets even better. Running economy improves by around 3% at the highest intakes – a meaningful gain in any endurance setting. On the downside, gut discomfort is highest at 120, but still well within what trained athletes can typically tolerate.  

These findings have the same compelling implications for the bike. The takeaway is clear and conclusive: most of us can use more carbs than we think, especially if we train our gut to handle them. 

Real-world fuelling. Food vs Supplements – What Actually Works

We’ve established, put simply, that more on-the-move carbs equals better endurance performance. So how do we get them on board? 

Pre-session fuelling would be unthinkable without regular solids. It is, rightly, built around them. But long distances and durations bring practical considerations.  

We all love a jam sandwich. But hauling a stack of them around a marathon course and then trying to enjoy and digest them on the move has very limited appeal.  

It’s time to talk about volume. 

Energy gels: Why Two Really is Better than One

It’s not hard to see why energy gels have become indispensable. They deliver high-quality, concentrated carbs quickly and easily. You know exactly how many you’re getting – crucial when calculating intake and timing. Most importantly, they do it with manageable volume, both in your pocket and in your stomach.  

But carb delivery isn’t just about how much you can gulp down – it’s about how much your gut can actually absorb and your muscles can actually use.  

Single‑source carbs (like maltodextrin) rely on just one intestinal channel. At around 60 g per hour, it can’t handle any more. Absorption stalls, and the excess sits in your system, feeling unwelcome and slowing you down. 

Dual‑source carbs (maltodextrin and fructose combined) change the rules. They tap into a second route, allowing more fuel to reach your muscles. It’s win–win–win:  

• Higher total carb absorption
• Faster delivery to working muscles
• Less undigested fuel sloshing around

It’s dual-source formulation that makes today’s 90–120+ g per hour approach possible. That’s how influential it is.

BETA Fuel: More Carbs, Less Stress

Extensive research has shown that a 1:0.8 glucose–fructose ratio is the sweet spot for high‑carb intake with minimal gut pushback. It offers key benefits: 

• Higher carb oxidation rates; more of the fuel becomes usable energy
• Reduced fullness and nausea; crucial when race intensity rises
• More stable blood glucose; fewer peaks and troughs

The result? A significant performance improvement. 

SiS BETA Fuel was the pace-setter and still leads the way. It raises the bar in endurance fuelling, and remains the most efficient method yet formulated to deliver very high carb loads with minimal gut stress. 

BETA Fuel’s celebrated high-profile wins are well documented. But it’s in fuelling everyday endurance – the long runs and rides, the big weekend events, the individual and team goals – that it changes the game.  

How to Build Your Carb Capacity

So, increasing your carb intake moderately can genuinely boost your performance. But you don’t leap from 60 to 120 overnight. Your gut adapts just like your engine does: gradually, through repeated exposure.  

Your training sessions are where you build – increasing volume, improving tolerance, refining timing, and finding your preferred products.  

If you’ve got an event to focus on, use your long outings to develop your strategy and rehearse fuelling on the move. When race day comes, you’ll know your target numbers and feel confident about hitting them.  

It’s a great feeling at the start line when you’ve got the science working with you. 

Fuel-first fitness: The new era of high-carb performance 

Endurance fuelling has come a long way. The carbs-per-hour ceiling has been raised repeatedly. What once seemed extreme is the new normal. The progress is impossible to ignore, as it fuels more and more medals and records. 

What unlocked this revolution? The science.

We understand that:

• Carb availability directly drives endurance performance
• The gut is trainable to handle greater loads
• Dual‑source carbs unlock higher absorption

The impact has been transformative. The results have been inspiring – and show no sign of slowing. 

High‑carb fuelling isn’t about getting through it – it’s about going beyond it.  

But here’s the thing. The lab breakthroughs powering these gains are no longer reserved for the elite. With quality fuel and a disciplined approach, we can all push our limits. We can all get to places we previously thought impossible. 

It’s time to unlock your own potential to go longer, stronger, and faster.