Fueling Zone 2 Workouts

But most people don’t ride every day. So your approach means that people have to change how much “real food” they’re eating every day, to account for how much they ride on any given day.

And what happens when life gets in the way of riding?
If I plan to ride in the afternoon, and eat a full breakfast and lunch based on that plan, but then my ride gets canceled, how would I maintain a caloric deficit in your plan? I think I would have to skip dinner, which isn’t healthy or sustainable.

For most of us, it’s easier/better/healthier to adjust our on-the-bike nutrition on days when we ride, instead of changing our regular food meal plan based on how much riding we plan to do that day, and to stick to the plan of riding that day.

Decades of behavioral science research showed that people are better off with regular routines around eating.

It’s really a shame that you refuse to accept that other peoples views are legitimate in this discussion.
Your dogmatic approach to never eat on the bike may work if you train the same amount every day, or if you are willing to change your off the bike meals significantly each day to account for how much you’ve ridden, but most of us don’t ride every day, and have real life that interferes with our riding plans sometimes.


I use MFP to track mine every day and most days i need to eat around 3800 (2300 bmr + 1500 ex. @ 74kg). A cheeky bowl of cereal or a couple of bananas goes a long way to keeping up the calories. It’s often a conscious thing though like last night, even after dinner, because of a 2 hour 1800cal early evening ride ride (3 gels) i was looking like going to bed 800 cals down on the day so I grabbed a bowl of cornflakes, a banana, an apple and some chocolate 15 minutes before bed. Problem solved.

I fuel every ride, I feel better and have a better controlled appetite the rest of the day. If I want to lose weight I’ll look at what I eat the rest of the day. Eating 500 calories on the bike for any hour long workout sounds better than not. But that’s me.

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Depends I will if it’s a straight out of the bed ride. Other than that it’s usually a 90g drink mix or 2 clif bars an hour.; that is 86g of carbs at 500 cals.

I’m also 6’3” 184 pounds and need to eat around 4000 calories a day for maintenance. I think weight and height play a role for how much people might fuel. I might be wrong but I don’t think a 5’6” 130 pound person needs to fuel like I do.

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endurance ride ( /inˈd(y)o͝orəns /rīd/ ) : a cycling workout to create a caloric deficit in order for one to reload glycogen stores with beer.



I also think you are using the extremes of fueling recommendations. 100+g/h is usually a recommendation for a long hard day/race pace. A practical recommendation to fuel a 2 hour endurance ride might be 50-60g/h. And as others have pointed out, it also depends on what your priorities are: weight loss, performance gain, or a combo of the two. It sounds to me like your focus is weight loss and you have found what works best for you. That is great, but many others have different priorities so some of your recommendations would not be good for them.

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Maybe I’ll regret posting in this thread. There are a couple of things that I think people are forgetting when they are thinking about the concept of fueling on long slow rides (ie: z2).

  1. A training ride is not a race. The goals of a training ride and how you do it, are often very different than what you’d do during an event.

  2. Different people have different purposes for their training. The “optimal” training of a pro riding 20-30h a week training for the TdF will likely be different than the optimal training of a MTB cyclist, will likely be different than the optimal training of someone who only races crits, will likely be different than the optimal training of someone who just rides three TR sessions a week over the winter so they stay in shape for group rides in the spring.

  3. If we are talking about whether to continuously take in calories on a z2 ride or not… this is a slightly different question than whether you should be doing fasted rides or not. Someone who eats breakfast, then rides for 4 hours with only a snack in the middle, is neither continuously fueling their ride, nor riding fasted.

That being said, what is the purpose of long slow rides?

We do them for a number of reasons. People talk about things like “improving muscle capillarization,” or “increasing mitochondrial biogenesis/density,” or “improving mitochondrial energy usage.” They all boil down to adaptations that allow your body to be more efficient at extracting mechanical work out of the stored chemical energy in your body.

Why do these z2 rides need to be so long (and low intensity)? Because the duration of time you are doing this training for is felt to the key variable that elicits these target physiological adaptations. It is the time spent doing the activity that overwhelms your bodies existing adaptations, and forces it to continue to adapt to this new stress.

What exactly is going on in your body that you are trying to overwhelm/train? What is the signal for beneficial endurance adaptations (like increased mitochondrial biogenesis?) THE signal which triggers many of the adaptations you are trying to gain from z2 rides is low energy levels in your muscle cells.

Specifically, AMPK is a major regulator of mitochondrial biogenesis in response to exercise. AMPK activity is triggered proportionally to a reduction in intracellular ATP levels. The lower the available energy in a given muscle cell (ie: lower ATP:AMP ratio), the higher the activity of AMPK, the stronger the adaptive signal for increased mitochondrial biogenesis/enhanced mitochondrial density.

You don’t need to reach a state of “glycogen depletion” for this to happen. Which is great, as your glycogen is never fully depleted anyways. Rather, the more of an intracellular energy deficit you’ve put your muscle cells into, the higher the degree of activity of AMPK, and the stronger the signal for beneficial physiological adaptations is.

This is why long slow rides have to be long. They need to be long enough that you overwhelm your body’s existing adaptive mechanisms to continue to provide energy to your myocytes (in the form of lactate, glucose, fat, etc.) during exercise, such that AMPK levels drop, and you get an beneficial adaptive signal. “Long” here depends on you and your training background.

In addition, low intracellular energy levels in your muscle cells are the major trigger for muscle-derived IL-6 release during and post aerobic exercise.. IL-6 is critical in inducing many of the other goal adaptations of long slow rides. Things like improved fatigue resistance.

Low intracellular energy levels in your muscles are also the key trigger for other cell signalling pathways involved in the adaptive response to exercise (ex: PPAR).

Long story short: the whole point of doing long slow rides/z2 rides is to put your muscle cells into a state where they are struggling to adequately get the chemical energy they need. This low energy state is the fundamental cellular signal that triggers most of the beneficial effects of z2 training.

The implication of this is that you will not achieve the full training benefits of your long slow rides, if you never actually reach a state where your myocytes are struggling to access enough energy to continue riding.

If you are constantly eating the entire time you are doing your long slow ride, the primary signal that elicits all the adaptive changes you’re trying to get by doing this ride in the first place would be expected to be gone. Or at least lower.

  1. Does this mean you shouldn’t eat any food during your events? No, that would be stupid. Training is different than an event. You should definitely consume lots of calories during an event as the goal there is performance, not to elicit a training adaptation.

  2. But so and so pro team does their training with consuming 120g of carbs per hour all day every day for all of their training rides. Sure. But many other pros don’t do this. I have no idea why they’re training that way right now, you’d have to ask them. Without knowing what specific training goals these people are going for when doing this, you can’t infer their behavior onto your own training goals.

  3. Fasted rides (or not) are a related but separate issue from the matter of continuously fueling during a z2 ride or not. You can see from the science above how it seems to make sense that fasted rides may be beneficial; however, I don’t want to get into that as it wasn’t the topic of this thread, and there are other variable to consider.

Edit: Also remember: long slow rides are not just long, they are slow. This is because you want to maximize the amount of physical activity you are making your myocytes do while in a low energy state. Doing a set of VO2 max interval will also put your myocytes into an energy depleted state… but for not as long.

Related - if you don’t eat anything at all during your z2 ride… it is unlikely you will be able to continuing exercising as long as if you stopped when you noticed you were getting hungry or slowing down, and ate some food.

My personal take away from all of this is that I will eat some food during z2 rides. I’m not trying to take in an absurd amount of calories per hour. But I’m also not trying to make myself bonk. I’ll eat breakfast, go for a ride. When I notice I’m getting a bit hungry or performace is dropping/RPE is increasing, I’ll eat a bit of something. Just enough that I’ll be able to actually finish the target duration of the ride without being so ravenous when I get home that I eat an entire bag of chips.


This is really bad advice. There’s a grain of truth to it, but in the big picture it’s not worth doing. Know what else works? Training. Crazy right?


I also have avoided posting on this thread, I guess for similar reasons, it is a bit like a TR cult, I heard this, it must be true in all circumstances without considering the context and goals of the session.

I would suggest the are a number of people that do not realisie the advice for threshold sessions, or a slightly down regulated version when applied to Z2 is blunting the adaptations, unless you have loads of time and can go even longer, but that is not your typical TR user.

There is alot of people that need to read the post quoted multiple times, hopefully they will finally understand instead of regurgiting sound bites from the TR crew that really doesnt apply to the goal of these Z2 sessions, they are relevant to tempo+ not really Z2 in most circumstances, context is everything.

If you still dont get it just do your reseach, tip it has got nothing to do with MaxFaxOx, and is more to do with maximal adaptive signaling re: mitochondrial biogenesis.


Sorry what? Riding fasted is better for body composition? Energy balance determines body composition. I have a large number of clients eating 50-120g/h on the bike who are losing weight (deliberately). The body is a better energy accountant than you seem to give it credit for. If it’s a thing that works for you, fine, I can’t and won’t argue that, but it is not therefore a universal principle.


I’m not sure I listened to the same podcast as you if that’s your takeaway, lol. Chad from 8:40 (discussing bonking) - “muscle depletion is not necessary to stimulate these aerobic adaptations he is seeking. You can under fuel, that’s the training low we just described that signals aerobic adaptation. Endurance training in and of itself stimulates aerobic adaptation, whether it be long slow distance, HIIT, sprint intensity training, etc. All of these things stimulate aerobic adaptation as long as there is consistency, recover, and proper nutrition. Going is route is far less detrimental to further training in terms of metabolic disruption, unfavorable hormonal shifts, muscle protein synthesis, immune health, literal danger on the bike, etc. So my short answer to a short question-sounds like a pretty unhealthy unpleasant way to achieve something that can be done in a better, safer, more productive manner.”

I think Chad agrees with what just about everyone has been saying: Have a snack and ride your bike.


Yeah, that prior summary/paraphrase above is misleading at best and way off the mark compared to what I heard.

I appreciate the transcript @BenB .


I think I discovered why you gained weight with that fueling strategy. Clearly if you’re adding hundreds or thousands of calories on the bike you do need to change your diet. Not to say you should or shouldn’t be fueling - but if you’re saying you aren’t able/willing to make changes to your off-bike diet based on your on-bike diet then of course your weight will change.

A lot of this discussion (on all sides) seems to be trying to remove nuance from a topic filled with it.

If you are purely chasing performance and have optimized your diet and body composition your on-bike fueling looks different than if you are chasing performance but have not optimized your diet and body composition. Likewise, if you’re chasing weight loss over performance your fueling (as well as your priorities) are different

For most people, if you’re trying to lose weight changing your off-bike diet is likely to help long term more than changing your on-bike diet, but this will be different for everyone. If, like @Crosshair indicated in his post above, you are unwilling/unable to change your off-bike diet then doing fasted and minimally fueled rides will be a great (or maybe your only) strategy to lose or maintain weight.

On top of all of this is what is your actual FTP in raw watts. Regardless of the above factors, if your FTP is 200 you should likely be fueling differently than if your FTP is 400. If you have an FTP of 400, even your Z2 work is going to be burning so many calories that under fueling can put you in a much bigger hole than Z2 for the 200 FTP rider.

As an example of the above - I did a 2:15 Z2 workout to start my day earlier this week where I burned just shy of 2200 calories. Could I have done this fasted? Sure. Would I have been in ok shape mentally for work while chasing that caloric deficit all day? Probably not. So I fueled with around 190g of carbs. If my FTP was 50% of what it is and I burned 1100 calories - I could’ve still fueled at the same level and been negative, but also could’ve gotten away with a lower level of fueling if I was trying to lose weight


I don’t pay much attention to fasted training, my take on the ‘science’ is that it is high risk / low reward. Not the kinda odds I want to play.


I think you’re just noticing the swing away from the fad of “fasted training”.

Just like Polarised and Zone 2 are in vogue right now. It’s all useful to pay attention to, but none of these things are the universal answer.

To answer the original question, I did my first “Zone 2” workout yesterday where it was set and forget. I didn’t fuel quite as much as SS, but it’d have been absolutely miserable without fueling, and I’m someone who can go out for 3-5hrs without fueling. I had 2 bottles of 100g each and 1 of 60g and made that last the 4.5hrs.

On the bike is genuinely the best time to start refueling for the next workout.

But endurance/z2 riding was never a fad, its been a mainstay of training. The fad was rejecting endurance riding in favor of threshold style, and then too much threshold style is being rejected by the polarized fad.


The fad is the extreme adoption of one methodology above all others and using descriptive trendy terms to prescribe training universally.

Of course endurance training is the mainstay of endurance sport. Lydiard was doing this “Zone 2” stuff forty years ago. Their training wasn’t Long Slow Distance.

Coaches have known the value of using different intensities forever. The fad is coming up with it and presenting it as new information that can apply to every single situation



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Crosshair in an earlier post you said you were rigidly holding to eating 1400 cal a day; now I understand! I’d be argumentative on the internet if I was eating a 3100cal deficit a day! :wink: