140g carbs per hour

Excellent! Thank you.

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Great question: hydration becomes so critically important for longer events that it trumps optimal fueling needs. Consuming 120g/hr sometimes marginally slows gastric emptying and ability to hydrate.

If you know for sure that you’re able to maintain 99+% of your body weight during very long sessions via adequate fluid and sodium intake, then you can certainly continue to push the higher rates of consumption. Best way to find out. Try it. If you don’t get gut cramps or GI issues doing >100g/hr in an 8-12hr event, then by all means increase carb consumption rate to 110 or 120g/hr and give it a go. Could also taper carb consumption rate throughout the event from something like 120-140g/hr at the outset down to 80-100g/hr when gut issues start to sneak up on you. The more practice the better, obviously.

Losses of >2% body weight are a near guarantee of needing to reduce hourly carb consumption rates. Down 1% BW and you’re starting to flirt with needing a slight slowdown.

In all honesty, I’ll probably update that when I write v2 of the book. I now think it can be safely pushed to 120-140, if in cooler temps or for a person who is a very limited sweater.

The book was written a couple years ago and while there still is not literature on those higher rates of consumption out past 3-4 hrs, in 2020 and 2021 I was able to test pretty extensively the high carb consumption rates out past 6 hours. Book v2 is a couple years away though. Other projects in the works first!


So when you state 120-150 g/hr, you mean for 2.5+ hours only?

Yeah or maybe 2+ hrs, rather than 2.5+ hrs.

If anything, I’m starting to think that many of the figures in the carb table I’ve shared could be a bit higher. There is not substantial scientific literature yet supporting this. I suspect that given 10-15 more years of testing with more optimal sugar ratios and higher concentrations for the 2-3hr range, we’ll see 120+ more commonly discussed there, especially in cycling where the tradeoffs are minimal.

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Just to confirm @Dr_Alex_Harrison: you’re talking about a 1:1 malto-fructo mix here? Do you use a 1:1 m-f mix for all your energy drinks, regardless of amounts and duration? For example, on shorter (30-60 minute rides) you’d be using between 20g and 70g of carbs in a 1:1 m-f mix?

I generally do 60-90% sucrose, and 10-40% Gatorade. Sucrose works as well as malto + fructose and is slightly lower osmolarity and slightly less sweet than a 50:50 malto:fruc mix.

Yes, I go pretty much 1.2:1 to 1:1 gluc:fruc all the time. Always via sucrose, which is glucose+fructose in one disaccharide, and Gatorade which is probably right around 2:1.


Everything I see talks about ratios from 1:1 to 2:1 glucose to fructose. Always more glucose than fructose. Has more fructose than glucose ever been researched?

What is happening when people take in more than 60ish g in a one hour workout? We see a lot of anecdotal evidence of success, but if that’s overkill, what’s actually happening with those extra carbs?

I’m very curious about this.

I go for 100g per hour. But if you have an FTP in the 300+ you literally cannot replace the amount of carbs you’re burning.

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If your gut is absorbing it, those carbs will be used to fuel the work or elevate blood sugar so that cognitive drive remains high, or both. Then subsequently re-pack muscle with glycogen post-workout if blood sugar remains elevated, as is ideal.

Yes but minimally. I think maybe 2 studies have investigated it. Only one of the top of my head. Rowlands and colleagues I believe. I think it’s a pretty safe bet that optimal ratio is somewhere between 0.8:1 and 1.3:1 gluc:fruc.

My intuition is that 15 yrs down the road recommendations will be something to the effect of:

If you’re doing 90g/hr, target 1.3:1
If you’re doing 100g/hr, target 1.2:1
If you’re doing 110g/hr, target 1.1:1
If you’re doing 120g/hr, target 1:1
If you’re doing 130g/hr target 1:1
If you’re doing 140g/hr target 0.95:1
If you’re doing 150g/hr target .9:1

Totally made that up on the spot, based purely on intuition. Also did no math to verify my logic.

If you have an FTP of 300+, you will never not benefit from more carbs, if gut-tolerance allows, for rides over 2 hrs. MAYBE for racing, maximizing carb intake isn’t so important and staying in the 90-120 range at 2-hr ride duration is reasonable, but for 2-hr training rides, there is very little reason not to encourage max carb availability during training to maximize recovery, adaptation, and future carb-burning and absorption ability in the future.


@Dr_Alex_Harrison - have I got this right: sucrose (ordinary, everyday, white granulated sugar) is just as effective as a 1:1 mix of maltodextrin-fructose? In other words, I can effectively and efficiently fuel all my rides on ordinary household sugar? If so, is there any difference between refined (white) and unrefined (golden)?

That’s how I see it.

What is sucrose ? Sucrose is crystallised white sugar produced by the sugar cane plant and can be found in households and foods worldwide. Sucrose is a disaccharide made up of 50% glucose and 50% fructose and is broken down rapidly into its constituent parts. Due to its glucose content, sucrose has a GI value of 65.

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Is there any difference on dental effect between using granulated sugar or a Malto/fructo mix?

My teeth are already in pretty bad shape so this is a worry for me.

Same here. While I like the idea of maximum fuel efficiency for minimal cost, I cringe at the thought of all that ordinary sugar swishing over my already battered teeth. Be interested to know, from a dental hygiene point of view, if all sugars are the same.

That’s how I’m reading it too. If that’s the case, a bag of ordinary household sugar is going to be a damn sight cheaper than bags of malto and fructo, which in turn are cheaper than branded energy mixes :thinking:

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I’m glad I’m not the only one reading it that way as I thought I was going mad. To me, it does everything you need without the faff of buying other products and even more expense.
I’ve been using plain white sugar for a while now and it’s been doing the job. However, I haven’t tried upping it to 140g per bottle.

If you carried two bottles, one with plain water and one with a sugar water mix, you could rinse your mouth with the plain water to help rinse away the sugar. I’m not a dentist, so this is just a thought.

Also from a taste point of view: I am not sure, but I think sucrose is tasting sweeter than a mix of glucose & fructose, right?

One of the things I like about malodextrin… it’s not as sweet as using sugar. Sugar is just so damn sweet!

Not according to Alex:

Oh, did not see that. Thanks!

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