Eating on the run

I have, for a long time, carried the childish nutrition belief that if I kept the over hot enough anything would burn. I often also held a maladaptive view that running was a tool to lose weight. This led to a pattern that I will gently call “unworkable” – I would eat like a slob and drink alcohol after my runs (or the night before a run) and also run almost exclusively fasted (without anything to eat before or during). In my mind, I had two voices. The first voice, the oafish rationalizer, told me that what I was doing was fine, that a little pizza and beer would burn away quickly. The oaf was quick to reward a run with a donut or to recite the prayer of junk food into my ear late at night:

Giving it good fuel would be irresponsible.

Our body is an economy car, it shall not want. Let us guide it to Taco Bells, lay it beside cool tubs of ice cream and drink from rivers of PBRs. Our body is an economy car, it shall require economy fuel. Lead us not into premium, organic, healthy fuel but deliver us from dieting – Amen.




COACH-- Craig T. Nelson
I wish Craig T. was the voice in my head

That voice cannot be found as I step out to run. The only voice with me is the punitive coach. It is the coach that points out the jiggle of my belly, waterlogged from the previous night’s feast. It is the coach that instills judgmental looks and guilty feelings as you eye the fridge before running – Eating again? Have you earned it? What are we working towards, anyways? Coach tells me I don’t need fuel on the run, that I have plenty stored up and Coach tells me that if I want to be a better runner I should stop eating. Coach is not a good coach – but then again, coach is typical of most coaches.



In my quest to become a runner, I have decided I need to eat like a runner. I have long understood, logically, that running requires fuel and that choosing the right fuel is important. While outside of running, I started to place focus less on cutting calories (ignoring the echoing voice of coach) and more on balancing out my macro-nutrients (protein, fats and carbohydrates). My in-run nutrition was the bigger challenge.


The goal of nutrition while running

Glycogen looks crazy

The main objective to pre- and during-run nutrition is obvious – getting fuel. More specifically, the goal of getting in fuel is to maintain a adequate level of energy (in the form of glycogen) in your muscles and energy (in the form of glucose) in your blood. A byproduct of an endurance event (typically determined as being longer than 30-minutes, Saris et al, 2003) is the gradual depletion of glycogen in your muscles and liver as well as a decreased concentration of glucose in the blood. With that in mind – high levels

Glucose just doesn’t want you to freak out

of glycogen pre-endurance activity typically lead to longer periods of time before you feel the effects of the activity. A review by Hawley and colleagues (1997 – dated but still important) found that becoming “supercompensated” (carbo-loaded) improves performance by 2-3% as compared to non-supercompensated athletes. It is important to note, however, that this was found for events longer than 90-minutes and there is little evidence of the benefits of carbo-loaded for shorter events.


Carbo-loaded typically occurs in the days leading up to an event. Pre-race consumption (<60 minutes prior to the event), however, has slightly more mixed findings that trends towards support for it being beneficial. While this last minute influx of carbohydrates may be beneficial for “topping off” your glycogen tank, it appears to have a much more significant impact on your blood sugar level. If your blood sugar dips too low (due to your boding using up the glucose too quickly) and you may suffer from some nasty side effects: fatigue, shakiness, anxiety, increased sweating, and irritability. In a nut shell – I am looking to find a suitable fuel source that will help to keep my body regulated, my mood in check and my energy level moderate to high.



Subject: To identify the most effective in-run nutrition for my body, I had to develop a standardized testing method. At the risk of stating the obvious, the method for nutrition had to be effective for me as a runner so I was the sole participant in this single-case study.

Nutritional Manipulation: In searching for food to take in during the run, I made selections based on four primary criteria:

Availability: Any option I chose must be widely available for both single purchase as well as bulk orders. I do not want to become reliant on a specific food source only to find I forgot to pack it for a travel race and I’m unable to quickly re-up at the expo or a local running store. This excluded some of the more exotic options (honey bites, exotic fruits and strange concoctions people make at home in under 90 minutes and swear they help).

Affordability: Along with being able to easily (access-wise) purchase whatever I chose, I also needed to be able to easily (affordable-wise) purchase the food. This excluded any options that weren’t relatively affordable as single units as well as anything I couldn’t buy in bulk.

Variety: While I am hardly one to get bored with repetitive food choices, I do like the option to make the switch between flavors to keep the relationship with me and nutrition spicy and alive. I wanted to find an option that had a fair bit of variety in flavor options. This excluded some fairly promising options that only had a single option for flavor.

Practical elements: Above all else, the food selected must have a profile that suites my needs. The three crucial factors are: high levels of carbohydrates, low levels of fiber and some amount of caffeine. The high carb to low fiber ratio ruled out a lot of the more natural options (peanut butter sandwiches, pieces of fruit, etc.). Additionally, the ideal running food has to be easy to carry. The preferable option is something I can strap to my belt and forget about until the time comes.

The final selection came down to three products: Sports Beans (by Jelly Belly), Shot Bloks by Clif and GU. Each of these came in a wide variety of flavors, were easily accessible both online as well as in almost every store I looked in, were affordable and were compact enough to store either within my SPI belt pouch or fixed into one of the elastic loops. As a point of comparison (a control group, if you will) I also did the run completely fasted (no food intake for 12 hours prior to the run, nor was there any food during the run).


Timing of intake Logic and research show that glycogen in the muscles are important for power output. However, there is less evidence on specifically when this fuel should be taken in. Anecdotal evidence across the internet range anywhere from 60 minutes prior to the run up to the first steps of running. For every testimony, there is the counter – people bemoaning the risks of eating too soon (triggering digestion which may increase your body temperature prematurely) or too late (leading to food being wholly undigested and, therefore, wasted).

Looking to the literature, there is evidence for the benefits of pre-activity carbohydrate intake (Jeukendrup, 2011). While some research showed that there is a risk of a glycemic rebounding (a sugar crash and dip in performance), Jentjens and Jeukendrup (2002) found that this is only a worry among a small percentage of insulin sensitive athletes and the general population should find benefit (or, at worst, no effect) in pre-activity carbohydrate intake. To maximize the benefit of the carbo-boost (while minimizing the risk of a crash), Moseley, Lancaster and Jeukendrup (2003) suggest ingesting five to 15 minutes prior to the onset of activity (as well as ingesting during performance. As for when to refuel while running, Jeukendrup (2011, same as above) showed that across the research there is little benefit for additional carbohydrate intake for any activity less than 30-60 minutes. While this range appears long (the difference of about 4 miles), I feel it is a safe bet that while within the 30-60 minute range (and, the closer you get to the 60-minute mark) the more you should start thinking about refueling. If you set the mark at a firm 60 minutes, and take into account the time it takes for digestion (the suggested 5-15 minutes) then you are hitting a refuel at roughly 45-55 minutes into your activity.

For the sake of standardization, I chose to time my intake at 5 minutes prior to running and refuel at 50 minutes.


Road testing: The tests were carried out on four successive Sundays (my typical long-run day). The benefit of running in Florida in June (when these runs took place) is that the weather is extremely consistent. Each morning the temperature was anywhere between 78-80 degrees with a high humidity mark (75-80%).

To prevent any confounds based on earlier nutritional variation, I ran each of these runs fasted (not eating for at least the last 12 hours). Also, as a product of my low carb diet, I didn’t have any alcohol the night before these runs nor did I go on any epic pizza binges. The run each week was the same – an 8.75-mile loop (see below) around the south portion of Tampa After taking in my fuel, I set a timer for 5 minutes, loaded up my GPS and started my music and, as the timer went off, I started running.

Screen Shot 2018-07-10 at 8.11.29 PM.png

Dependent Measures:

While running there were four factors I was focusing on to make my final judgment.

Ease of intake. I wanted to select the product that was the easiest to eat both prior to running as well as while I was running.

Stomach feel. While all of these items were low fiber, the final decision will decide largely on how the food feels in my stomach. Does it sit too heavy? Do I feel ill (either due to the food itself or the psychological effects of eating it)? Do I lose control of my bowels?

Subjective improvement. What is the mental impact of what I am eating? Is it enjoyable and do I feel like I am doing better? For short runs, this may not matter as much but for longer races feeling faster could easily translate into going faster (and for longer).

Objective performance. Can I see any changes in my performance? One large disclaimer is that there is a very limited sample of data to pull from so any surface level differences may be anomalies. However, I am not rich nor do I have a wealth of time to dedicate to testing the scientific merits of choosing one food stuff over the other. Small data and large leaps of faith will have to do.      


Trial 1: Running fasted


Ease of Intake: There was no intake, besides water, so it was pretty easy. It is important to note that this is my typical form of running (completely fasted) and a style I am trying to buck. However, for the time being, it felt comfortable and predictable.

Stomach Feel: I felt fine. I definitely noted some hunger towards the end of my run as well as some vivid daydreams of what breakfast would be.

Subjective improvement: Again, being the control group there is nothing to improve upon. However, I did notice more negative thinking during this run compared to the others. I found myself much more judgmental of those around me and caught myself having imaginary arguments during future (and, unlikely) situations. Additionally, my legs felt heavy during the end of the run.

Objective performance: For ease of comparison, I will present these findings (as well these findings for all trials) in a separate, consolidated section below.

Trial 2: Shot Bloks by Clif


Ease of Intake: While sitting in my car pre-run, I found that the shot bloks were pretty easy to take in. The overall stick is broken up into six pieces making it easy to partition out depending on how much you want to take in at a given time. The blok itself reminded me of a giant fruit snack that I would have likely found in my lunch as a child. Slightly denser than those snacks, they took a fair deal of chewing to get through. I ate three blok pieces, waited five minutes and then started running. I found myself picking pieces from my teeth over the first mile of my run. At the refuel point, I pulled the shot bloks out of my SPIbelt pouch and started eating again. The first blok took a fair deal of chewing to get down. The chewing, combined with a stuffy nose, left me gasping for air in between chews. I washed down the blok with water and went for a second. The second blok was even more difficult because I was already fairly out of breath and rhythm from the first. It was a strange feeling, breathing so much more heavily while trying to eat.

Stomach Feel: Fairly quickly my stomach began to turn and I decided to pass on the third blok. I cannot be certain if it was the blok itself or the quick shift in physiology (increased heartrate, increased breathing) that made my stomach feel off. I didn’t feel sick. Instead, my stomach felt heavy and uneasy – like I may get sick. This feeling wore off about ¼ mile down the road.

Subjective Improvement: For the first portion of the run, I felt pretty good. After the mild discomfort in my stomach wore off I felt okay. There wasn’t a huge boost or some magical change. I just felt normal – which is a good thing.

Trial 3: Sport Beans by Jelly Belly


Ease of Intake: The Sport Beans had a similar issue with the Bloks – lots of chewing involved. Another barrier to taking in the sports beans was their packaging. While the Bloks were arranged in a 6-piece stick, making it easy to keep together and pull out individual pieces, the Sports Beans were loose in a bag. Eating them while driving to the start of the run was a bit difficult to navigate. Pouring the beans out into my hand and keeping control of my car was surprisingly difficult to balance. I also attempted to monitor how many beans I was eating, which proved to be a futile effort because I lost count and didn’t really know how many beans I was starting with. The package the beans come in also didn’t neatly fit into my SPIbelt or into the pocket of my running shorts. I was worried throughout the run that I would have loose Jelly Beans rattling around. Taking them in during run had similar problems as the pre-run intake – lots of chewing, hard to pour out, hard to monitor how much I was taking in.

Stomach Feel: I didn’t have the same distress in my stomach that the Bloks gave me. Once I finished chewing and managed to swallow, the Sport Beans sat easily in my stomach.

Subjective Improvement: I felt good starting the run – my legs felt light and the pace felt easy. The running felt pretty comparable to having pretty well rested legs. This effect wore off pretty quickly into the run and about 20 minutes in my legs started feeling heavy and sluggish. Sticking to the protocol, I waited until the 50-minute mark to eat again. The refuel had a mild (likely placebo) effect and left my legs feeling lighter again for about another 10-15 minutes. Throughout the run I also noticed similar cognitive negativity that I felt during my fasted run. I had a lot of judgmental thoughts about myself when I felt my pace dipping. I also noticed a lot of mood flair-ups the closer to the refueling time I got.

Trial 4: GU


Ease of Intake: Once I got past the idea that I was eating straight frosting, the Gu was pretty easy to take in. The most important thing to making the intake easy was to drink water almost immediately after swallowing the Gu. On my first squeeze, my mouth was left sticky and my throat felt almost clogged. One quick squirt of water completely washed everything down. The packaging of the Gu is very compact (fitting neatly into the loops of my SPIbelt) and the top is easy to tear off with my teeth. The Gu packet is designed for you to take in all in in one go so it’s a pretty all or nothing thing. Pre-run, it was a bit tough to eat the entire Gu (more of a mental struggle with eating a shot of frosting) but in-run it was really easy to eat and put the wrapper in my pocket (keep Tampa clean!).

Stomach Feel: The Gu is extremely low on GI-impact. After eating (and drinking some water), my stomach felt fine. There was no full-feeling or turning. It was as if I didn’t eat anything at all.

Subjective Improvement: Taking off on the run after the first Gu shot, I felt great – light legs, easy-smooth pace and focused on the run. I started to dip around 45-minutes in with my legs starting to drag me down and my brain trying to talk myself out of running any more. After re-upping with another Gu shot, I felt that reverse pretty quickly. Again, this may have been a placebo effect (subjecting myself to a blind trail would be difficult and something I don’t want to figure out and orchestrate). Regardless, the back portion of the run felt strong. I was able to put my focus back into my pace and felt a second wind coming in. Throughout the run, I mentally felt stable and quiet. I was able to listen to my music, keep my pace and I didn’t notice any automatic judgments or critical thinking.


Objective Performance:

Running chart.png

Posted above is a graph of pace, by mile, for each of the fuel sources. A quick glance shows one concrete finding – I appear to run better when I eat something. I suspect Science or, at the very least, Nature will want these findings for their next issue but Run Exp has the exclusive rights.

A few other things jump out:

  • There is only one trial for each fuel source so take all of this with a grain of salt
  • I started fastest with Sports Beans but also faded the most quickly and ended the slowest
  • Bloks had a similar trajectory – start fast, fade quick. There was a re-fuel boost from the bloks that led to a decent closing to my run
  • Gu had the slowest start (that was due to technical problems with my headphones during that run) but then had the most consistency in my pace and the fastest kick.


I shouldn’t be running long runs fasted – that’s the first and most conclusive result. If I want my long runs to be meaningful miles I need to fuel-up.

The second important finding is that Gu appears to be the best-suited fuel source for my running. On the three subjective measures (ease, feel, improvement) I felt the best, had the easiest time and at least subjectively felt faster while taking it. While objective measures have some mixed results (along with significant limitations due to sample size), it looks like the Gu had the biggest impact on late-run performance. As a typical fast-and-fade style runner, refueling with Gu mid- to late-run may help prolong the fade.

Congradulations, Gu! You should be very proud.







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