Is the current High-Carb training paradigm total BS?

Training
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I think you’re missing a few important distinctions here.

First, maximizing fat oxidation during exercise doesn’t necessarily mean greater body fat loss. Burning more fat during a session isn’t the same as losing more body fat over time. Overall energy balance is what determines fat loss

Second, your maximum absorbable training load isn’t independent of fueling. Carbohydrate availability affects training quality, glycogen replenishment, and recovery. Proper fueling can actually increase the amount of productive training you can absorb, rather than simply helping you reach a fixed ceiling.

I think the mistake is assuming that maximizing fat oxidation is equivalent to maximizing endurance adaptations. They’re not the same thing, and deliberately restricting carbs could mean sacrificing training quality and recovery without actually becoming a better athlete.

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22

I think the question wasn’t if fuelling is necessary, but if high carbs are hype. Some answer sounds like the second.

If someone does 3-4 hours a week on the bike, and is eating a “typical” western diet, do you really think you need more carbs also during your workout? If someone has a 200w FTP and is maybe riding usually at 120w for 1 hour?

If you are a pro, riding 20h at 300w, then it’s absolute necessary to fuel as much as you can.

But I would argue that the general recommendation to fuel (as much as you can) is wrong and it depends on the rider.

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I think people can benefit from proper carbohydrate fueling regardless of how much or how little they train.

But I think you’re still missing the distinction I was trying to make between exercise fueling and general nutrition.

Exercise fueling has three parts: pre, intra, and post. Ideally, you should fuel across all three based on the demands and goals of the workout, as well as your overall training.

I’m not suggesting everyone needs 100g of carbs per hour. Someone riding easily for an hour probably doesn’t need any additional intra-workout carbs if they’ve eaten beforehand. But that doesn’t mean carbohydrate availability isn’t important.

Personally, even for those one-hour sessions, I find it much easier to simply bring and consume 100g of carbs during the workout rather than plan an additional 100g carb (400 kcal) meal beforehand and time it so it’s properly digested and not sitting in my stomach. That’s a practical preference, not a claim that everyone needs that much.

Generally, I think people should aim to adequately fuel their training and manage any desired calorie deficit through their overall nutrition, rather than deliberately underfueling workouts to lose weight.

Once you start looking at the actual energy demands of longer or harder sessions, it becomes clear how useful higher intra-workout carbohydrate intake can be. Even longer easy sessions can benefit, particularly when you consider the impact on recovery and subsequent training.

The goal isn’t to consume as many carbs as possible. It’s to fuel the work you’re asking your body to do, regardless of whether you’re training 4 hours or 20 hours per week.

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24

This ^.

Fatmax training isn’t going to help you lose a meaningful noticeable amount of fat nor is it helping your performance much if you’re someone new to training with lower hanging fruit to go after first (consistency, sleep, structure, adequate recovery, etc.).

You don’t need to do 100-120g carbs/hour like a 5 watt/kg pro. Most of us are going to be fine shooting for something in the normal-person range, like 60-90g carbs/hour - and only if you are doing a ride over an hour. Your carb needs vary depending on the intensity and length of each ride.

Personally, I feel like rubbish when I don’t fuel my rides - and then I spend the next day or two feeling ravenous. Not good for fat loss, trust me. Fueling my rides with carbs has been the best thing I’ve ever done for losing fat, ironically.

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25

“Fueling my rides with carbs has been the best thing I’ve ever done for losing fat, ironically.”

You are not the only one, here is an experiment done by Roadman podcast Anthony Walsh, about which he wrote

“Following the periodised (feeding) approach for 60 days produced stable or slightly lower body weight, improved power, and consistently higher energy levels.”

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26

The topic of FatMax and carb-restricted training is very popular and interesting. For many years I believed that improving fat metabolism was possible only with restricted carb availability. Training without breakfast, without extra fueling.

But when I dug deeper into this topic, I realized — fasted training doesn’t improve fat metabolism, but it creates a lot of stress that’s very hard to dose, and fasted training can very easily even worsen your results.

FatMax assessment is quite reliable, possible on a metabolic cart test. Where you can see that carbs start being used from the very first minute of the workout, but at some point fat usage starts to decline — that’s the FatMax point: the maximum intensity at which high fat utilization is still maintained and the fat/carb ratio is 50/50.

Here’s an example of a treadmill test.

image
image1073×637 84.2 KB

The yellow line is carbs in grams per hour.
The white line is fat in grams per hour.
The fills are calories from the substrate.

At about 9.5 km/h (or 6:19 pace), my fat burn is 60 grams per hour, and carbs 15 g.
At about 10.5 km/h, or 5:43 pace, fat burn is 54 grams per hour, carb burn 48 grams per hour.
Whereas already at 11 km/h, or 5:27 pace, the ratio becomes 51/60.

So I train fat metabolism at intensity no higher than 5:43, and ideally maintain a pace of 6:00–6:19 min per km.

However, if I run 3 hours at 5:27 pace, that burns ~150-180 grams of glycogen and creates excessive stress. There’s nothing wrong with consuming about 40–50 grams of carbs, sparing your glycogen, while fat utilization doesn’t change — meaning the fat metabolism training is preserved.

Second example: when I rode the bike without fueling, holding stable intensity (via ventilation control), I could observe that my power after about 2 hours (when, by mathematical calculation, I’d burned about 120 grams of carbs) started dropping sharply, by almost 50%. After taking carbs, about 40 minutes later my power came back, but not to the original level — only to about 80% of what it was at the start.

What conclusions do I draw:

Fat metabolism training is necessary for an athlete, but that doesn’t mean you should restrict carbs. And how many carbs — depends on your intensity and your gut’s ability to absorb. Of course, there’s no point for me to take in 120 grams. But you definitely need to fuel. It will only improve your results.

I’ll add more:
after I stopped restricting carbs during workouts, my feel for the load got much better. My recovery improved, my training volume went up. It’s all very subjective, but for me it’s really obvious. And I think fasted training is evil. But you need to dose fueling consciously.

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27

People can “benefit” from “proper” anything.

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28

You started this thread with a question to the community here, and plenty of people speaking from their own experience and experiments and from the science they studied are giving you balanced insights. I don’t understand why you are contributing to the conversation you started with passive-aggressive comments only. This is not Reddit.

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Do you think your graph would be the same if you did the test after a ‘properly’ fuelled 3 hour run at 6:00 - 6:19 pace?

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I haven’t done that, so it’s hard for me to say. Probably something would change. After all, the body isn’t a high-precision mechanized machine. Deviations would most likely occur.
But I know for sure that without fueling my power/pace will drop significantly more than with fueling, and I’ll be forced to shorten the workout. And if I try to hold them, the stress will probably be too much. So with fueling I can increase time under load in the Fatmax zone without excessive stress.

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31

AIUI that - power / pace dropping significantly - is due to glycogen levels in the muscles dropping past a threshold level.

Being more aerobically efficient is one way to delay the onset (when working aerobically) and fuelling the work with carbs is another.

There are sound reasons that one might incorporate depleted glycogen workouts in a properly structured plan - most of which are covered in the papers and other resources I have linked previously.

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Attention is the answer

34

Test it yourself. Go do a 6 hour ride with 3 x 30m sweet spot intervals along with mixing some upper LT1. Once with low carbs and once with high carbs and see for yourself. Shoot just go do 6 hour ride with low carbs and high carbs and report back how you felt after and later on in the day and the next day when you ride again, and the day after that.

Also, how you mix your carbs is important too. When you crank up you need to use maltodextrin and fructose instead of just sucrose (table sugar) to reduce osmolality and don’t forget salts.

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35

Hexis changed the way I fuel and approach recovery. The push updates quickly too. It may not be of value for all, but for me it was instrumental in my progression.

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I think that your response illustrates a fundamental misunderstanding of my question.

And in many ways this misunderstand is part of the issue I’m trying to illuminate.

I do not dispute that eating a certain amount of carbs will improve my performance for a ride, for even 6 weeks, etc.

My question is, is it optimal for LONG TERM performance. Especially considering my upper limit of absorbable load, anecdotally, is sleep and mood degradation from sustained load.

And I apologize to the readers who view my replies as passive aggressive or what they perceive to be attention seeking. Not sure how you would reply to any thread without it grabbing attention.

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I agree that training with depleted glycogen has its value, but from my point of view it’s not in training fat metabolism, but in greater stress for the body with less duration. The same stress, but less time. But without proper control it’s dangerous, and I don’t know of any reliable control tools.

Whereas long workouts in the FatMax intensity zone with reasonable carb support increase training time in the effective zone with less stress for the body. Gas analysis testing shows that carbs are used from the very first minute of movement, just like fat, but at some point as intensity rises the share of fat use declines. My task is not to exceed that intensity, but at the same time not to let glycogen become fully depleted

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38

My thesis is that the upper limit of your absorbable load would reduce if you did not fuel properly.

It could be that what you think is your current upper limit could be increased with proper fuelling. It could be that you actually went through your upper limit in your experiment.

Properly, in my definition, is avoiding persistent glycogen depletion and managing diet / nutrient breadth off the bike, rather than on it.

Your current mix of carbs:fat may, or may not, be optimal for you. Maybe more fats would benefit you.

There may be some other nutrient that you are lacking or overdoing.

If you want to get into it seriously, most specialists would recommend a series of bloodwork across a 3 - 6 month period to establish some reliable base data to work from.

Sustaining a work load close to an athlete’s upper limit for is a serious business and is best taken seriously.

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39

Rather than debate this abstractly, here is the experiment I have actually been running.

On September 22 I started riding carb-restricted. I have ridden daily, doing what I call my fastest moving FatMax rides, and I have also gone to the gym each day roughly six hours before the ride. “FatMax” here is my practical pacing label, not a lab gas-exchange claim.

My body mass has fallen from 74.2 kg on September 22 to 69.1 kg this morning.

I then looked at the FIT files in a fixed mechanical-work window: kJ 599–1,199 from the start of each ride. This avoids comparing fresh riding with the finish of rides of different lengths. Thirteen rides reached that point.

In that fixed work slice:

  • Power rose from about 155 W to 170 W
  • HR rose from about 119 bpm to 130 bpm
  • Raw watts per bpm was effectively unchanged: +0.6%
  • Power per kg rose from 2.09 to 2.46 W/kg
  • Power per kg per bpm rose about 7.9%

So my observation is not that carb restriction has produced a dramatic increase in absolute cardiac efficiency. It is that, after 599 kJ of work, I am producing more relative power at a substantially lower body mass while maintaining roughly the same watts-per-beat relationship.

My next hypothesis is about acute fueling, not long-term adaptation: now that I am at this lower weight, I suspect a strategically carbohydrate-fueled one-off test would quickly improve the absolute result—either more power at the same HR or a lower HR at the same power—compared with remaining carb-restricted. I would treat that as an acute fuel-availability effect, not proof that I should be high-carb every day.

The clean test is to repeat the same ride at the same body mass and compare only the kJ 599–1,199 segment: once carb-restricted and once with deliberate carbohydrate before and during the ride, while holding gym timing, route/trainer, pacing, hydration, caffeine, sleep, and preceding load as similar as possible.

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40

It is interesting data.

It brought a couple of things to my mind, some of which might be relevant.

5.1kg weight loss in 18 days is pretty dramatic, but not off the charts for a switch to low carb. A chunk of that can be down to water loss. Keeping an eye on electrolytes is sensible. If you notice headaches, that could be a sign of low electrolytes.

The change in watt/bpm shows that you were at a decent aerobic fitness level already (given what you have done in the past months, that can be no surprise).

Are any of the fatmax rides so long that you reach glycogen depletion (if you aren’t sure, they aren’t: you would notice it!).

Acute fuel availability effect. The concept of “train low, race high” was prevalent for a while. It has its place.

I expect that this structure will work (i.e. the numbers will improve) until it doesn’t. If I was to guess, that would happen somewhere around 5 - 6 weeks from the start.

Once the numbers stop improving (as quickly), it could be time for a new training stimulus for a while.

That could fit well with your hill climb coming closer. Timing a specialty training block, to match the effort needed in that event, probably wants to be mostly completed 3 weeks or so before the event, doesn’t it?

Ed Laverack - a half decent climber by anyone’s standards - is vlogging his training for the British Hill Climb championships (this year is a 4.1mile climb with 13’30" - 14’00" on the cards). You might find a couple of his recent videos an interesting way to pass the time on a trainer ride? https://www.youtube.com/@edlaverack

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You’re right that weight loss will work until it doesn’t. But the same is true of high carb diet gains. You can get gains until you don’t.

Against my hypothesis is that high carb isn’t the one-shot performance solution most hold it out to be.