Less Is Not Enough: The PodCaster’s Approach to Nutrition

Posted by Filed Under: Nutrition

Article Summary: This is part two of debate on long run/marathon fueling strategies. In part one, Mark Iocchelli put forward the case for a minimalist approach to fueling (less is more). In part two, Steve Runner takes the opposite view – that fueling on the run is the advisable strategy. In part three, Lee Miller discusses how the body metabolizes food for energy.

steve-runner.pngWhat we have here, with the proclamation of Mark’s “au naturelle” approach to pre-race nutrition, is a failure to correctly estimate the biochemical properties of fuel storage within the human frame. I don’t want to say that Mark is “wrong” in his statements regarding energy capacity and usage during endurance event—because we’d need a bigger, more explosive word than “wrong.” My thesaurus only came up with three pertinent synonyms, including “incorrect,” “mistaken,” and “erroneous.”

Mark is no doubt a gifted athlete and well versed in the physiology of the dromedary genus “camelus” or the herbivorous endurance mammal “antelope,” but he demonstrates a remarkable lack of understanding for the species he claims to be a member of!

Dr. George Sheehan, cardiologist, author and legendary “running philosopher” wrote that “we are an experiment of one.” He explained that each of us has to learn what works best for our bodies, and that the road to improved performance demands careful observation when we test theories as they apply to ourselves.

Mark has made and reported on his careful experiment of “one”; now I’ll share with you results from my little experiment of one.

My approach to marathon fueling is not only based upon running 15 marathons, but is based upon running 15 marathons badly! I have made every mistake possible when I’ve embarked on my 26.2 mile “journeys,” but like any self-observing scientist, I’m eager to learn from these mistakes, and to avoid them in future races.

This is the same logic adopted by the NASA rocket scientists who calculated the exact amount of fuel required to land men on the moon, and return them safely to Earth.

The Space Craft Analogy

As a self described “goofy little Podcaster,” I have often been accused of being a little “spaced out,” so it should be no surprise that I would contest the “Running Blogfather’s” approach based on the following observation: When I’ve run races where I’ve not correctly fueled myself before and during the event, I’ve crashed and burned well before “re-entry.”rockets.gif

So, what does rocket science have to say about marathon fueling?

1. You have to “refire” the engines during flight.

It’s useful to remember Newton’s Second Law of Motion, where the force required to do something is a function of the mass of that “something” (in this case, you), and the acceleration to velocity of that “something” (your average pace after the start of your race).

Force requires energy—a spaceship needs fuel to blast itself off the planet, and you need fuel to blast off over the starting line.

But just as in space flight, there comes a point where, during your run, you need to “refire” the engines.

As you’re running your race, you have within your muscles the necessary glycogen fuel to enable you to maintain the force required to move your body towards the finish line.

So far, Mark and I are in agreement. But, now comes the tricky part: the human body is a great rocket ship, but it has a woefully small fuel tank.

2. You need more energy than you can carry.

When the rocket scientists did the math, and calculated the amount of fuel they’d need to get to the moon, they realized that the less the space craft weighed, the less fuel they’d need to carry. They also realized that they’d need more energy than they could carry, to power the lights, fans, heaters and pesky oxygen generators which would be required on their mission.

How easy it would be for us to run a marathon with our limited fuel storage if we could eliminate the need for our own lights, fans, and gizmos as we traveled from the start toward the finish.

Generally speaking though, we have only a few hours worth of fuel in our muscles. In his book, Lore of Running, Dr. Tim Noakes devotes his third chapter to “Energy Metabolism During Exercise”:

… fat is the largest energy store in the body. By comparison, the carbohydrate stores are quite trivial.

Which would seem to support Mark’s claim that conversion of fat into fuel is the best way to fuel a marathoner, since by volume there is more “Fat Fuel” than there is “Carb Fuel.” But most male marathoners have a mere 15 percent body fat, while women typically have 25 percent. This might seem like a lot, but in practice it doesn’t work as well as glucose fuel.

Noakes writes that:

Studies show that glucose either taken by mouth or infused into the bloodstream during exercise does not reduce the rate of muscle glycogen utilization (which slows after several hours of running) … rather, this glucose is burned by the muscles in place of blood glucose derived from the liver.

So, it’s clear that there is a finite amount of fuel you can carry within your muscles, blood stream and fat stores. Further reading of the Noakes’ tome shows that the rate of fuel usage is a function both of the intensity of your effort and the duration of your run.

Such was the dilemma of the Apollo astronauts who had no choice but to use a supplemental energy source, in the form of solar power, for their journey to and from the moon. They, like you, cannot carry enough fuel for the mission at hand, thus it becomes necessary to fuel on the run to supplement the “on board” energy that you’re carrying with you.

3. Load ‘em up and feed ‘em while they work.

My heroes are glycogen and sucrose. These are the key fuels needed to power our human spaceship. Even after a good training season, my body’s ability to free fatty acids from my triglyceride molecule stores isn’t efficient enough to get me past the glycogen wall. Instead, I’ve found that my body performs well if there’s a steady stream of incoming glucose to feed my muscles directly, saving the glucose in my liver for a strong finish.

The rocket scientists who plotted out the lunar excursion of the early 1970’s used batteries and hydrogen fuel cells, with minimal use of solar panels for supplemental energy. These lunar visits were mere sprints, however, compared to the plans that NASA has for our return to the moon in 2020.

The “Crew Exploration Vehicle” that is going back to the moon will be powered by two solar panels, able to power the spacecraft for up to six months, and capable of generating 40 percent more power than the Apollo Fuel cells were able to.

This new strategy for spacecraft design is closely related to my personal strategy for running a marathon. I’m able to run a 10K without much fuel in my body, but for a marathon I need to bring it with me, and consume as I go.

4. Look Ma, No Fat!

The problem with most well-trained marathon runners is that we haven’t got the luxury of fat stores. Compared to non-endurance athletes, the percentage of fat we have within our bodies is low, and there isn’t an ample supply for glycogen to hand off to Mark’s “fat hero.” I agree that there is a huge benefit to training our bodies to make the conversion from glycogen to fat storage, but if you’ve been running marathons for as long as Mark and I have, your ectomorphic frame likely doesn’t support a lasting supply of the “jiggly stuff” (fat) thus making the hand off to the backup fuel a problematic exercise in chemistry.

5. Push Back the Wall.

runningonwall.jpgI agree with Mark’s philosophical preference to go “au naturelle” en route to a finish line which rests 26.2 miles from the start, but that attitude is likely based on the assumption that running a marathon is a “natural” thing to do. Most of us don’t run a marathon distance on a typical day, in much the same way that most astronauts don’t blast off to the moon with much frequency. Distance running, especially over the 20 mile threshold, is generally an extreme activity which calls for extreme measures, and while there’s a definite satisfaction in knowing that you completed the distance with only those chemicals you loaded in your spaceship prior to launch, it is assumed that fluid replacement is an important and necessary supplement for your run.

Our goal is to push back the glycogen wall of exhaustion by any means necessary, and it’s this runner’s opinion that supplemental fueling using gels, bars, cookies and candies which supply the blood with useful sources of sucrose is an important way to achieve that “push back.”

Let’s Check the In-Flight Recorder

Fueling: According to my painfully detailed running log, I’ve run 15 marathons since 1999, but that doesn’t make me an authority on such events. Admittedly, it’s been my lack of in-race fueling that has prevented me from colliding with the glycogen wall. While I have dabbled in the use of gels, cakes, bars and most recently “chewy cubes,” my inconsistent use of these caloric supplements has yielded a PR. While poor fueling does not account for all of my problems with weakness, in the late miles of a race, it has contributed greatly to my demise after mile 20.

In one of my rare moments of “doing it right,” I ran my marathon PR in Lowell Massachusetts in October 2005 (Phedippidations PodCast episode#15: “The 2005 Bay State Marathon”), and made a point to consume unsavory globs of pasty gel packs in an effort to properly fuel myself for a strong finish. Even then, I didn’t fuel myself to perfection, but I did overcome my complete lack of appetite and crossed the finish line in marathon record of 4:23:06.

No-Fueling: It is only my opinion (a valueless item that fellow runners who listen to my podcast would no doubt concur with!) that Mark’s success in his marathon occurred most recently after a change in his running form, training plan and shoes—all more significant factors in comparison to his change in fueling.

In October of 2002 I ran the Mystic Places Marathon in East Lyme, Connecticut, after a proper taper with low glycemic carbohydrate rich foods in the meals prior to race day. On race morning, I ate a few “nutrition bars” and vowed not to eat anything during the race itself, so as to keep my stomach clear of pesky food stuffs.

I barely finished the race after a grueling and powerless 4:58:13. I proved, to myself through this “experiment of one” that supplemental fuel intake is an important and fairly necessary element to my marathon plan.

Where we Agree

Even though I believe that you should fuel yourself during your distance runs to supplement your body’s fuel stores, I agree with Mark that you have to toe the line with a fully fueled body, and that through proper training, your fuel stores will increase to a point where you can power your body to reach at least the two-hour point.

The problem is that I am a four-hour marathoner, as are many of the fellow runners who will pin on a race number and face the 26.2 miles of a road race this year. We may not be running to the moon, and this may not be rocket science, but the principle of carrying supplemental fuel for the long run seems to work for me.

Losing weight is a wonderful thing, and best achieved through proper dieting and endurance exercise, but running a marathon is a challenge that requires every advantage you can manage to carry.

How much you should carry is something you’ll need to calculate for yourself; every body (and spaceship) is different, and I’ll refrain from offering a mathematical formula for you to determine your own energy needs.

Besides, I’m horrible at math.

Run long and taper!
Well, you’ve read both arguments. Now, you get to choose – and make sure to leave us a comment!


  1. Run to Win on June 19th at 9:18 am

    Do you refuel during your marathons?

    At Complete Running, Mark Iocchelli and Steve “Runner” Walker are debating about whether or not you should refuel during a marathon or whether you should just stick to water. Both make some good points, but I definately side with Steve on …

  2. 21stCenturyMom on June 19th at 9:50 am

    I’m not answering the poll because it is too black and white.

    I think a gu at mile 20 of Mark’s PR marathon would have really helped him out. I also think that people who insist you need fuel every 45 minutes are going overboard.

    My biggest concern with the au naturelle approach is that there is one muscle in your body that won’t benefit from burning fat and that is your heart. Cardiac muscle can only process glycogen and if you happen to deplete the glycogen stores around your heart then BOOM! You’re dead. That is why people with severe anorexia drop dead of heart attacks. Therefore, I’d be very careful about using a strategy that depletes glycogen and starts burning fat. I’d like to know that your body will burn fat before it goes after your cardiac glycogen stores before I tried that trick.

  3. Mark Iocchelli on June 19th at 11:39 am

    21st: I think we need to realize that fat doesn’t actual fuel the body – it is broken down into fuel (e.g. glucose) that the body (including the heart) can use.

    As for the gu at mile 20, I disagree. I’ve ran several marathons eating gus that didn’t stop me from hitting the wall. In contrast, I did not hit a wall at mile 20 in this last marathon. I slowed at about mile 22 but this is because I am not yet as efficient at burning fuel as I could/want to be.

    However, I do not say you are wrong – or that Steve is wrong. I think we have to figure out what our goals are for a marathon and choose a strategy that works for ourselves.

    As for the poll, we’re just trying to have a little fun. 🙂

  4. Blaine Moore (Run to Win) on June 19th at 12:14 pm

    Mark, it’s all about finding what works for you. I had a lot to say so I put it up at RTW, but if you can find some sort of food, beverage, or gu that can replenish your fuel as you go along and you start well before you need it, then you are less likely to run out during the race. That’s my take, and it works for me, so I’ll keep with it until I decide to experiment with something else.

  5. Mark Iocchelli on June 19th at 12:19 pm

    Blaine: Yes, it depends on what you want to do with your marathon experience. My goal is to teach my body to provide the fuel it needs. I had success with this approach in my last marathon but I am by no means finished with deploying the strategy. I am still very much in the “teaching my body” mode. 🙂

  6. Adria on June 19th at 1:12 pm

    You state that in practice, body fat does not work as well as glycogen for fuel. I am wondering where you’ve drawn that conclusion. (I know absolutely nothing about this topic but am fascinated, as I have plenty of body fat I’d like to convert to fuel.) Which brings me to my next question, if the marathoner *does* have excess body fat would you agree that not fueling mid run is the way to go? And if not, why not?

    I have enjoyed both articles.

  7. Mark Iocchelli on June 19th at 1:51 pm


    As I understand it, it is not that fat does not work as well as glycogen – it is that is has to be broken down into glucose. In other words, there is an extra step(s) in order for your body to use fat. The small supply of glycogen stored in your muscles and liver are easier to access and use up. The trick is getting your body to become *good* at accessing and breaking down fat.

    My opinion about your question relating to fat is this: If you have excess fat that you want to lose, not fueling is a viable option. If you think about calories in versus calories out, if you put fuel in your body during a run, it will not be forced to burn fat.

    So, if your goal is to lose weight by burning off fat, not fueling during a long run should be right up your alley.

  8. Lee Miller on June 19th at 2:40 pm

    Hi gang. Let me throw in my 2 cents worth. It is my understanding that glycogen is required to power the fat for fuel process. Fat has the potential for the most energy then any other fuel source. Fat has 9 calories per gram versus 4 calories per gram for carbs and protein. In distance running, we burn a mixture of these sources, but primarily fat unless you are going at a very high intensity.

    Both points are well taken, but if you run out of glycogen, the “pilot light” that kindles the other fuels for running goes out. BONK!!

    As far as marathoners having little body fat say 5%. That means a 140 pound marathoner has 7 pounds of fat. This is potentially 28 602 Kcal of energy to play with! Don’t forget that fat is also stored throughout the body not just on the butt and gut.

  9. Mark Iocchelli on June 19th at 2:58 pm

    Excellent clarifications, Lee!

  10. Dawn - Pink Chick on June 19th at 5:25 pm

    Mark while I would clearly love to agree with you I can’t. For me running a marathon is practically an all day experience. I wouldn’t sit at my desk for 7+ hours and not eat, I sure as heck ain’t gonna run for that long and not fuel.

    For my last marathon I had 6 gels and a few other items. I suspect I didn’t consume any more then 7-900 calories but my Garmin says I burned over 5000 so heck I think I could have eaten an extra large all dressed pizza along the way and still lost weight…lol.

    Despite eating a great dinner that night and eating appropriately the next day I was still down 3 pounds from my race two days later.

    Maybe I will rethink things if and when I get down to a 4 hour marathon but for now bring on those chocolate cherry gels and keep em coming.

  11. Mark Iocchelli on June 19th at 5:36 pm

    Dawn and others:

    I hope you can see that I’m not saying you MUST do as I am doing. I am just saying that there is an alternative to what is often taught.

    I think people should experiment and figure out what’s right for them. My approach is just another thing to think about.

    And I hope everyone realizes that Steve and I are really having fun with this. My calling him a “weenie” and his jabs at my intelligence were all in fun.

    We’re here to entertain, inform and provoke some thought. 🙂

  12. Jennifer on June 20th at 12:20 am

    “21st: I think we need to realize that fat doesn’t actual fuel the body – it is broken down into fuel (e.g. glucose) that the body (including the heart) can use.”

    This is actually not true. Fats are broken down by an independent mechanism which produces energy without producing glucose first. I’m not sure about the heart, but I do know that our brains can only be fueled by glucose.

    Fat does fuel the body (other than the brain) through a process called fatty acid oxidation. It produces more energy than glucose oxidation, but at a slower rate.

  13. Mark Iocchelli on June 20th at 7:59 am


    My (“e.g.”) was not accurate so thanks for the clarification. I was not intending to delve deeply in the chemical process. I know you have a background in sciences – would you mind providing a clear explanation OR some links with easy to understand explanations of a) what happens when fat is broken down and b) the precise source of fuel fat becomes?

    That would be very helpful to everyone. We might include it here in the comments or even as a standalone post.

    This has been a very good discussion everyone!

  14. Ebitty on June 20th at 11:15 am

    Both articles were extremely interesting! Thanks guys!
    The thing that sticks out to me the most is the simple time logistic. With Steve continuing to run almost a full hour longer than Mark, it makes sense that he found more benefits using gels and other fuels later in the race. If they were running the same race, Mark would like be having a bagel and banana right around the same time Steve pops in in a gel pack.
    At any rate, they both have found what works for them and should be commended!! I hope to some day get to the point of finding out which method works the best for me!

  15. Less Is More: The Blogfather’s Approach to Nutrition » Complete Running Network on June 27th at 2:43 pm

    […] one, Mark Iocchelli put forward the case for a minimalist approach to fueling (less is more). In part two, Steve Runner takes the opposite view – that fueling on the run is the advisable strategy. In part […]

  16. A Power Primer » Complete Running Network on June 27th at 2:48 pm

    […] one, Mark Iocchelli put forward the case for a minimalist approach to fueling (less is more). In part two, Steve Runner takes the opposite view – that fueling on the run is the advisable strategy. In part […]

  17. Al Kind on November 2nd at 7:10 am

    …Generally speaking though, we have only a few hours worth of fuel in our muscles…”

    very interesting.. i didn’t think that because i thought people could survive days without food…
    .-= Al Kind´s last blog ..Needing Cushion Running Shoes? =-.

  18. Jon (was) in Michigan on November 2nd at 10:16 am

    You are correct, Al, you can live for days without food. But your body will be burning fat, not glucose or glycogen, during those days of no food. The fuel stored in your muscles get used up quickly. If only we could burn fat more efficiently, we could run for days without stopping. 🙂
    .-= Jon (was) in Michigan´s last blog with the new(er) =-.

  19. Al Kind on November 9th at 6:43 am

    again very interesting jon. Is glycogen the only way to power our muscles? Shouldn’t there be a mechanism in which our muscles should be able to function ( albeit, not at peak effeciency ) without the presence of this “fuel”?
    .-= Al Kind´s last blog ..Needing Cushion Running Shoes? =-.

  20. silo moreal on October 29th at 8:56 am

    You’re quite right, weight loss is best acheived through smart dieting and nutrition, and the correct types of exercise might I add. Marathon running according to studys will result in loss of lean muscle tissue, something that peopl dont want, replacing this with a higher intensity and lower duration exercise such as sprinting, or boxing, or even weight/resistance training. Some deep thoughts and information in this post, thanks for that.