Fueling Zone 2 Workouts

More to this side AFAIK. I’m not as well-read on many of these studies as some others here, but the ones I have seen where they’re seeking to show glycogen depletion/fat utilization as a performance benefit, the evidence is repeatedly quite weak (or it even shows it as a detriment to performance as in the study I linked 100 posts ago).

Doing the longer many month studies on stuff like this is going to be really challenging because not many trained athletes are going to want to experiment with a training intervention that’s as uncomfortable and potentially performance-limiting (as possible as it is performance-enhancing) for many months. So what you’re probably going to end up with is some college students who aren’t particularly well-trained doing these studies and often times when people like that do anything consistently for several months their performance is going to improve. It’s a real challenge the science side of this has to overcome.

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Nothing has made me cast a critical eye over physiology studies like being the questionable college student who participates for beer money.


Doesn’t deprive me of any food, I am just less hungry after a fuelled endurance ride and have more energy for the rest of the day. Our metabolisms are all different and there are many different ways individuals react to the same stimuli, that’s why there are so many different weight loss “diets”, it’s not a 1 sized peg problem.


Same. I don’t need to take in many carbs during an endurance ride, but a little goes a long way in preventing me from raiding the local bakery after the ride or generally being tired the rest of the day.

Also, some make it sound almost like carbs on a ride can only consist of sugary water. Personally, I prefer something that is more satiating.

But we are all different.

As long as you pick simple carbs that are quick to digest.

If this is the case it doesnt matter what you eat on the bike(if you burn more then you consume). You are eating too much off the bike.


Thanks for the explanation. Let me just clarify two things: (1) I just wanted to test my understanding with regards to wanting to become fuel adapted and the underlying mechanism. (2) I shouldn’t have written that muscle glycogen is being (completely) depleted, but that this graph suggests that after hour 4 muscle glycogen dose not make a meaningful contribution to total energy expenditure, it is just fat and exogenous carbs:
I meant that after 3ish hours they reach a threshold and at least in my experience my body reacts quite differently when it comes to fueling.

Perhaps the study this graph is taken from does not represent the state of the art.

Certainly, I have no interest in becoming fat adapted. It wouldn’t make any sense for me. I wish I could do regular 4–10-hour rides, but with two young children at home, that’s currently not an option. My endurance rides are currently 3-hour rides with my kids in tow. :slight_smile:

So this is specifically about you and not a general statement? As a general statement I dont agree with it.

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I think you miss that fasted ≠ fasted. As others (including @kurt.braeckel, I think) have pointed out, when coaches prescribe fasted rides, it does not mean that the athletes don’t take anything in during the ride.

Disagreeing with you is different from missing your point.


If you need to loose a few kg of body fat, your mindset should be: I need to change my eating habits little by little, such that my body eventually will not be able to hold as much fat.

What doesn’t work is thinking that you can eat the same as before and use those 1000 or 2000 kCal from a bike ride as pure deficit that will get you to the desired weight.

It doesn’t work like that because there is an unlimited amount of kCal available around you and you have an appetite that is fine tuned to keep your weight stable.

To loose weight you need to eat less than you want to.
Not a lot, just a little and you need to do it all the time, at least on average over each week.

When on the bike the best you can do is get stronger, which means going harder and longer and you need fuel for that.


That really depends on the rider, and type of events they do. Not every UK cycling discipline is based around summer events only.

My experience of long Z2 rides without eating is that it takes longer than that for me. But then I have 13 years of audax / brevets under my belt, plus over 40 years of riding my bike 5 days a week, starting with school in the 70s and never stopping.

As this thread is demonstrating everyone’s mileage varies when it comes to the length of Z2 rides they can easily manage without eating or performance decline or hunger issues.

It’s an interesting topic for sure.


There are some strong feelings in this thread but in my opinion at least, it is easy to see why, and here it is:

We have done the

Fuel every workout for gains!
Don’t diet on the bike!
Raise your FTP and you’ll naturally burn more calories
Your body composition will take care of itself!
You will be faster with higher FTP even if you weigh a little more!

The problem is some athletes still put on extra body fat and that isn’t optimal. If you put on weight during base, overfuelling Z2 workouts, that means you have to start having a caloric deficit if you want to lose weight before race season. That means during your build phase, which has obvious negative aspects.

I’m not sure I believe in the whole “teach your body to burn fat” thing, but I definitely believe its possible to get too much pure sugar as our bodies become more efficient on the bike, and we are losing out on good nutrients and fiber by drinking rocket fuel instead of eating balanced food during Z2 efforts.


Looking for a balanced approach has no place here!

I think before it went down a rabbit hole, several people said they fuel, but don’t focus on it for zone 2 to the same degree especially in the context of outdoor group rides. But anything diet/ nutrition brings out more extremes than polarised v sweet spot!


Appropriate term for carbs :laughing:

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I don’t know of anyone who prescribes rides where the athlete does not take in anything except water, unless that ride is very short (e.g. less than 2 hours) where that might be how you handle it anyway. I certainly don’t know of anyone I respect who is telling people to go ride 3+ hours without any caloric intake. In most cases, the way I see “fasted” rides prescribed is you ride before a substantial meal, maybe on 10-12 hours of no food consumption (overnight), but you don’t limit carbohydrate intake during the ride. In other words, you come into the ride in a carb-depleted state, but you don’t deny your body exogenous carbs during the workout. In one case, I know of a coach who would have you come in carb-depleted and then take in only water for the first 20-30 minutes or so, then fuel as normal. I understand the physiological thought process behind it, it’s just not something I think is probably worthwhile for the people I coach.


I would not use you as an example for the broad majority of cyclists. As I mentioned above, for audax/brevet/ultra-endurance (24 hour or unsupported adventure rides) being fat-adapted and worrying about substrate utilization might be more meaningful. For the average road/mountain/gravel racer who’s doing 1-8 hour events with access to adequate carbohydrate sources, it’s not going to be performance enhancing to chase it, IMO.

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Yeah I meant zone 2/endurance rides. Should’ve been more specific. I don’t know of anyone who prescribes fasted interval sessions. Some people do them because of time or whatever, but I don’t know any coaches who say, “Go do 2x20 at 97% before eating and don’t take in anything.”

As I’ve mentioned, the mantra of 100g/hr no matter what is just as bad advice as the guys running around saying don’t fuel anything.


OP how thare you asking such a question?!?! :rofl::rofl:

As you might have noticed there is quite a few passionate people around. :stuck_out_tongue_winking_eye::stuck_out_tongue_winking_eye:

You don’t give much background info and you didn’t specify a goal, so the advice is a bit generic.

For 2-3h true Z2 you don’t “need” to fuel, but if you choose to so, you might find controlling after ride cravings easier and if you’re working out next day, it might aid your recovery (although 24h of nutritious meals should do the trick anyway).

As you implied it’s a bit of a limbo. I would personally play and see what rolls for you. You can then come to the forum and give your anecdotal experience! That’s what I did :stuck_out_tongue_winking_eye::rofl:

My advice is based on potatoes and some first hand experience… and a bit of pragmatism!

Enjoy your rides!


This may be a large part of the confusion for a lot of folks with regards to fueling. I don’t use TR anymore, but the vast majority of my rides would have been 1 hour or a 90 O/U type workout once per week. Even if it was a SS or thresh session for one hour I wouldn’t fuel for it, but I would for a 90min SS or thresh session. I also wouldn’t for a 2 hour or less Z2 ride. I certainly would for any type of ride over 2,5 hours though.

Most people just don’t ride long enough or hard enough to warrant the fueling we are talking about here. I think it’s kind of that simple. If you ride long enough and hard enough, you’ll know you need to fuel! If you choose not to for some reason, you will likely stagnate and not improve as you won’t be able to do the necessary work.