On a 6 hr. ride, I will burn around 4,800 cals.

Assuming I start the ride fully carb loaded with around 1,500 cals in me, that means I will have to consume an additional 3,300 cals over the 6 hours, or 550 cals/hr.

  1. Is it at all realistic to try and do this during the ride using real food ONLY (whole grains, fruits, veggies), with NO sugar (ie. no gels, powders, or energy bars, etc.)?

  2. If sugar is a must, and there is no avoiding it, I would at least like to eat the maximum amount of real food, then supplement with sugar. So, what is the maximum cals/hr that the digestive system can metabolize into energy?

EDIT: Please see my answer below. Thanks to everyone for the great points.

  • 7
    Why no sugar - is it medical or life style? Reason I ask is many people in the life style camp do not understand there are different types of Sugar and go to extreme lengths to avoid "Sugar" and avoid the "Good when needed" and the bad. In the case of a 6 hour bike ride, balanced intake of Glucose good.
    – mattnz
    Commented Sep 28, 2014 at 21:02
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    @StephenTouset - There is a chemical distinction between sugars and more complex carbohydrates. Grains have relatively little sugar in them. Commented Sep 29, 2014 at 0:56
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    You don't indicate how hard you plan to ride, but a person in reasonable shape could easily ride 6 hours at a touring pace without eating anything at all. That said, it's probably a good idea to east something, and any sort of carbohydrate will probably do -- whatever tastes good and sits well on your stomach. You don't need protein, especially since it often comes with fat (which is a bad idea, usually). Commented Sep 29, 2014 at 1:01
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    Pure glucose makes it into the blood within just a few minutes of eating. Other sugars take longer, but will probably have "kicked in" within 15 minutes or so. Complex carbs take on the order of an hour. Commented Sep 29, 2014 at 1:04
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    Why are you stuck on you must consume the calories during the ride? The body will break down body fat. Eat healthy on and off the bike. Contrary to another comment - healthy eating includes protien and fat. bicycling.com/garmin-insider/featured-stories/…
    – paparazzo
    Commented Sep 29, 2014 at 14:15

7 Answers 7


Most sources I've read suggest that your body can process at most 300 calories per hour during exercise. And a lot of sources suggest that you only attempt to replace roughly 200 calories per hour at best. You should be able to do this easily without any simple sugars. Your initial budget is much much larger than 1500 calories, you don't need to do a one for one replacement. In endurance events your primary energy source is body fat, not muscle glycogen. You've easily got a 10K calorie reserve.

I've done a fair number of Road Centuries and 8 hr MTB races over the last 10 years and overeating is just as bad if not worse than undereating. There are some companies/groups ( Hammer Nutrition ) that recommend avoiding simple sugars altogether and only consuming complex carbs.

There's nothing that works for everybody and everything works for somebody. The only way to know is to try. One thing I've found that works really well for me is steamed mini potatoes with a little salt and olive oil.

Eating and drinking a little bit as constantly as possible works the best. For a 6 hr ride, I'd focus more on proper hydration and a good balance of electrolytes. Unless you're at less than 5% body fat, you've got plenty of reserves for a long ride. What eating does is allow the body to use it's reserves[1].

Getting all this right is very tricky, most people err way too much on the side of over consumption. ( I know I've been guilty of this and it's led to some pretty terrible results. ). It's very easy to overthink and over plan all this, ( and there are certainly a lot of companies that will gladly take your money along the way. )

What you eat or drink is generally far less important than that you eat and drink something that agrees with you and that you like eating and drinking. You need water and electrolytes, enough calories to make them enjoyable is really all you need to worry about.

[1]- This is just my own theory based on 35+ years of long days in the mountains, but often even just a tiny intake of food will yield a big jump in energy. I'm convinced the body "hoards" reserves until it detects an incoming supply of energy.

  • 2
    You're right, and I certainly think there is more to this than meets the eye. I lost a lot of weight through cycling, but just going on the distance/time I was doing, that should never have been the case.
    – PeteH
    Commented Sep 28, 2014 at 18:11
  • +1 - I agree, any food gives a huge bump in energy, if you know there's a punishing climb coming eating anything in the 15 mins before it gives back exponetially. Also I think people put too much thought into trying to avoid 'processed sugars'. You can make your own electrolyte replacement drinks, but it's like drinking warm sea water. Flavoured ones do the trick for me. I usually throw a chocolate bar or flap jack in my camelback with water if doing a long back country ride, just enough to get me home. In a race I take a couple of gels and a bottle of electrolyte replacement.
    – DWGKNZ
    Commented Sep 28, 2014 at 23:10
  • What's really odd is that every study shows that it takes at least 45 mins for any digested calories to be available for uptake in the muscles. Yet there are also studies that show a benefit in performance for even small amounts of calories in the 10 minute range. Commented Sep 29, 2014 at 0:35
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    @Fred: Pure glucose is what the muscles use - it does not need digesting, just absorbing. Sucrose (i.e. table sugar) is to all practical purposes 50/50 Glucose/Fructose). Complex carbs, Fructose, Fat, Protein and Alcohol (I just had to add that one in :) ) need processing (digesting) to convert them to glucose before they can be used by muscles.
    – mattnz
    Commented Sep 29, 2014 at 6:27
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    There's research to support his idea that your body opens the reserves when it detects future energy coming in: pbs.org/wgbh/nova/next/body/… (Sixth Taste on Our Tongues May Unleash Our Energy Reserves)
    – mplewis
    Commented Sep 29, 2014 at 19:36

You don't mention where you get your calories burn/hour rate, but 800 cal/hour is a very fast ride. 800 cal/hour would be around 220 watts, and that's a lot for 6 hours.

When you are riding, some of your energy is coming from carbohydrate metabolism, and some is coming from fat metabolism. The ratio between the two depends upon how hard you are riding, your personal fitness level, what kind of training you have done, and your genetics. If you are riding at your limit, you are burning a lot of carbs, if you are just spinning along, you aren't burning that many.

On a 6-hour ride, a decent guess at your ratio is something like 75% fat / 25% carbs. You don't have to try to replace the fat when you ride since we all have stored fat, so you merely need to replace the carbs. If you were burning 800 cal/hour, that would mean that you would need to replace around 200 calories of carbs/hour.

You don't need sugar to replace carbohydrates; any simple or complex carb will work, assuming that you tolerate it well. What somebody can tolerate depends a lot on their genetics and effort level; if you are riding hard, you might have to try a few things to find something that works.

  • There's not a direct conversion between calories to watts. 800kcal/hr is way beyond plausible — typical rates, even for a hard ride, is somewhere around 300kcal/hr. Commented Sep 28, 2014 at 23:00
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    It's a happy accident that the efficiency of the human engine means that you can multiply the average watts X 4 and get a rough estimate of kcals burned. Human engines aren't particularly efficient. Commented Sep 29, 2014 at 0:40
  • @StephenTouset - I weigh 185 lbs, and ride at around 16 mph, so that comes out to around 817 cals/hr, based on this chart: nutristrategy.com/caloriesburnedcycling.htm. Another chart pegs it at around 700 cals/hr: coach-hughes.com/resources/calories.html
    – keymaster
    Commented Sep 29, 2014 at 13:03
  • @Eric Gunnerson - on what are you basing your guess of 75% fat / 25% carbs, on a 6 hr ride? If that's true, problem is solved, as I know I can digest 200 cals/hr of whole grains fruit, and veggies.
    – keymaster
    Commented Sep 29, 2014 at 13:25
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    @Keymaster - most of the charts for calories burnt/hour are overly optimistic. In the ride I listed in my last comment, I averaged 17.3 mph, which the charts suggests is over 900 cal/hour, but my actual burn was only 2/3 of that. Commented Sep 30, 2014 at 4:07

Why do you want to try and do this without sugar? Sugar isn't dangerous for you if your body is using the energy. I would also question the difference between getting sugar from fruit vs getting sugar from a protein bar.

If you want high calorie/sugar intake from fruit, try to look for fruits that are higher in sugar/calories such as mango. You might want to try eating dried fruit as it's a lot easier to consume on a bike. Raisins are high in calories and easy to find, but you should be able to find dried mango if you look around.


I’m the poster of the original question. I thought several of the answers below made good points, especially @Fred the Magic Wonderdog and @Eric Gunnerson. But none quite put it all together the way I would have liked. However, by pulling together and organizing the many good points made by different people, I’ve come up with the following answer.

  1. Unlike in a race where you are burning almost exclusively carbs, on a long distance ride you are burning a combination of body fat and carbs. The body fat is unlimited, so you only have to replace the carbs portion. The proportion of body fat burned, depends on how hard you are pushing yourself. Pushing less hard means more body fat and less carbs are being burned, pushing harder means less body fat and more carbs are burned.

  2. If your pace is such that you can carry on a conversation, you are burning 75% of your calories from body fat. You don’t have to replace that. The remaining 25% of calories is from carbs which you do have to replace.

  3. If your pace is faster, so you find it difficult to carry on a conversation, you are burning 50% of your calories from body fat, with the remaining 50% of calories coming from carbs. You only have to replace the carbs portion.

  4. When I ride I generally find it difficult to talk, so I guess I should be replacing 50% of calories burned. In my case, that’s 400 cals/hr.

  5. However, since the body can only digest maximum 300 cals/hr, there will be a deficit of 100 cals/hr.

  6. This deficit will draw on the carb reserve of 1,500 cals which you should be coming into the ride with.

  7. You should be carb loading the night before and the morning of the race, so you come into the race with this reserve. The carb reserve is essential for making up the difference in the burned carbs you need to replace and the maximum 300 cals/hr limit your digestive system can process.

  8. At a deficit of 100 cals/hr, your carb reserve should more than cover a 6 hour ride. In fact, in theory, your reserve should allow you to ride this pace for 15 hours without a break (an unlikely scenario for anyone)

So, the answer to the original question is, yes, it is realistic to fuel a long ride with NO sugar. Thanks everyone.

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    I think you put too much faith in (overly simplified) math. While you touch on several of the significant points, the whole picture is much more complicated than that. Commented Sep 30, 2014 at 15:39
  • Lot's of people ride at a relatively high pace for 15hrs or more, 24hr MTB races are one example. Commented Sep 30, 2014 at 19:28

In my experience, eating any form of sugary food greatly increases the chances of a debilitating 'hunger knock' - all the more so if used to bridge times when your reserves are low. For me, sugar plays no part in any endurance diet.

Reward, however, is another matter. Where I used to take a couple of (say) mars bars on every road trip, nowadays I take only small amounts of dark, bitter chocolate. With that, peaks and troughs are ironed out, but I still have a something more or less special to look forward to.


I have riden 7 Ragbrais and nener needed any sugar packets or candy bars. Assuming you have the time to stop and eat real foods and you have trained your body well you should have no problem. On Ragbrai we ride an average of 70 miles a day for 7 straight days. Longest day is a century. You do need to train to keep this up.

  1. I eat a full meal at least every 2 hours and you have to be comfortable riding right after eating.
  2. I do eat sugary snacks- pie, root beer floats, etc.
  3. I start my ride eating a protien bar, stop for a full breakfast after 15 - 20 miles.
  4. Figure 2 full breakfasts, 2 lunches, and an afternoon meal with a few snacks along the way.
  5. Avoid foods that are hard to digest. The 2 lb pork shop might look good but your digestive system is not going to like it.
  • Oh come on, you can't not stop at Mr. Pork Chop at least once! It wouldn't be RAGBRAI without it! Commented Sep 28, 2014 at 19:27
  • I do stop at Mr Por Chop, but only once in a week. :)
    – Gary E
    Commented Sep 28, 2014 at 20:34
  1. You should pick up a copy of Allen Lim's cook book "The Feed Zone" the introduction explains a fair amount about exercise physiology.
  2. While on endurance pace rides don't eat anything for about the first 1.5 hours, this will train your body to efficiently burn fat. As others have said your body is burning fat in an effort like this, get your body use to that and you'll be surprised how long you can ride without needing to eat.
  • It would be good if you also gave a bit of information on the philosophy espoused in the book in mentioned in (1).
    – Batman
    Commented Sep 29, 2014 at 15:04

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