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The Marathon Fueling Episode!

In this episode we discuss how to fuel effectively for a long run or race. Plus, we answer questions sent in from listeners about carbo loading, considerations for female athletes, and fueling for an ultra.

Marathon Fueling

We haven’t done a podcast episode focused on fueling for long distance runners in a long time. It can often be challenging to figure out what your fueling strategy is going to be, especially for your first half marathon or marathon. To complicate matters further your fueling tolerance can also change over time. Sometimes you need to go back to the drawing board and reevaluate what you’re doing. Figuring out a fueling strategy can often be quite challenging because there is no one-size fits all formula.

The Basics

Your body burns through approximately 80-100 calories per mile (or per 1.6 km) while running. The total calories will vary based on your weight, amount of muscle mass, pace/effort level, and environmental conditions. The body stores fuel in the form of glycogen and keeps around 1200-1800 calories readily available in the muscles (and a small amount in the liver). The amount of muscle glycogen will also vary based on your size, muscle mass, and how carefully you’ve trained your body to absorb carbs (like during the refueling period post-workout).

During a longer run your body will burn a combination of carbohydrates, fat, and protein. If you run hard you’ll burn mostly carbs while easier effort running taps into your fat reserves. The body can also break down muscle to convert to energy which is definitely not something we want to be sacrificing. That’s referred to as muscle catabolism.

Dozens of products to choose from at a specialty running store

Pre-run Strategy:

If you’ll be running for less than 90 minutes you don’t necessarily need any pre-run fuel. If the run is at an easy pace you may not need any fuel at all (everyone is a bit different). However, if you find your energy levels dipping during a run of 90 minutes or less, a pre-run snack can be beneficial to perform your best. Just make sure that you leave plenty of time for your body to digest the food so that you don’t have stomach issues/GI distress.

Running makes digestion challenging for the body because of the constant motion. Blood is shunted away from the gastro-intestinal (GI) system for priority use by the running muscles. This can make adequate digestion (and avoiding nausea and diarrhea) a bit of a trick. Some runners are very susceptible to “dumping syndrome” while running. Basically your body decides that the food in your stomach can’t be adequately digested and sends it on the express route through the intestines (and into a port-a-pot or nearby bathroom if you’re lucky).

Running More Than 90 Minutes

If you’ll be running for more than 90 minutes make sure that any pre-race meal that you eat is finished at least 3 hours before you start, especially if you have a sensitive stomach. This is the amount of time it takes for the blood sugar and insulin levels to return to their normal state. If you eat closer to a long run or race your body may burn through your glycogen stores more quickly and it can cause a drop in energy levels while you run.

If you choose to eat before your race or long run you’ll want to eat something high in carbohydrate with some protein but low in fiber and fat. Make sure this meal is finished approximately 3 hours before your run (especially if you struggle with GI distress). Some people have “iron guts” and can almost eat anything before and during running. Others have such touchy systems that it can be a challenge to figure out a good fueling regimen.

Running in a Fasted State

Many morning runners do their shorter runs in a “fasted” state. That means they don’t eat (maybe other than coffee) before heading out the door. It’s actually okay to start a long run or race with an empty stomach too. I know that this may seem counterintuitive and a little scary at first.

It was a hard concept for me to accept at first too. I was used to eating around 1 ½ to 2 hours before my long runs and marathons to provide the fuel I thought was necessary. I was sure that my oatmeal and a banana was a good thing. However, I couldn’t figure out why I had a constant churning in my stomach during the first few miles and then experience a blood sugar “crash” at about mile 6-7. It was a huge moment for me when I realized that my pre-race meal was to blame.

During your night of sleep the body is in fasting mode and it hangs onto its store of glycogen in the muscles. The muscle glycogen is sitting there ready to go no matter if your stomach is empty or not. The only thing that gets emptied during the night is the glycogen store in your liver. The goal of the pre-race meal is simply to top off the liver glycogen store and this can be accomplished right before the race without negatively affecting how your body burns the muscle glycogen.

My Experience

For many years now I’ve used the approach of not eating before a race or long run (who wants to get up at 3-5 am to eat anyway). It was a little scary at first heading out with an empty stomach. However, the new strategy worked! I would simply start my fueling strategy right before starting my run and then keep up with a steady fueling plan for the duration. No more churning stomach and energy crash! It’s definitely something to experiment with if your current strategy isn’t working well.

I’ve stared many marathons without eating breakfast

Since I’ve started sharing these new fueling recommendations I’ve heard from many people on this topic. Some said that they were skeptical and hesitant to not eat before a long run. However, once they’ve tried it, the response has been overwhelmingly positive. People are reporting fewer stomach problems and steadier energy.

Trouble Shooting GI Distress 😬

  • If you’re having continued stomach issues on your long runs you can try changing to a different sports drink or fueling product. Read labels because certain sweeteners like fructose, maltodextrin, agave, and stevia can cause problems for some.
  • Another strategy to try is to make sure your pre-run meal is finished at least 3 hours before exercise.
  • You may also want to avoid dairy products because many people are lactose intolerant and don’t know it. The deficiency of the enzyme lactase can cause cramping, bloating, gas, and diarrhea.
  • A final cause of GI distress for some people is their caffeine intake so try cutting back on that A.M. dose of caffeine to see if that helps.

One thing that’s important to remember with fueling is that the goal is not to replace all the calories you burn. Your body simply cannot digest that many calories while you run. You’ll be in a calorie deficit (especially during long runs) but your body is equipped to deal with that.

So, when you’re figuring out a fueling strategy for a long run you don’t want to plan on consuming 1,000 calories if you’re running 10 miles. Men can usually take in a higher range of calories per hour while women should plan on using their body weight as a starting point. For example if you’re a 150 pound woman then try consuming 150 calories per hour while running.

What to Eat During Your Run:

Your long runs will be the time to try out various fuels and figure out your strategy. There are many different options available. Here are a few of the more popular options:

Energy Gels

  • How many will you need?

    An energy gel usually has a syrupy/gel-like consistency and provides carbohydrates to the body quickly. In the same category as gels would be most chews, GUs, blocks, chomps, sport beans, etc.. Most contain around 100 calories per serving. Gels are frequently provided at a couple of aid stations during marathons. Some people also find that the concentrated sugar in gels makes them sick to their stomach. This is because most gels have approximately a 73% concentration of sugars and the stomach isn’t equipped to deal with that effectively. You’ll notice that most gels recommend that you take it with 2-4 oz of water to reduce the concentration and help your body with absorption. The recommended use of energy gels is using one 5-10 minutes before starting a run if you’re starting out fasted and then one every 25-40 minutes thereafter (depending on your personal calorie needs). The amount of gels (or related products) you’ll need to consume depends on your metabolism, body weight, how much your system can absorb, and fitness level. The brand of energy gels you choose will be based on your personal preference and taste. If you have a sensitive stomach do some label reading to see what kind of sugars are contained in the product. If taking a whole gel at once doesn’t work for you it may be wise to take ½ at a time washed down with water from an aid station. That reduces the amount of sugar that hits your system at one time and gives it more time to absorb. If you’re planning on using the fueling products from an aid station during a race it’s wise to practice with that fuel during your long runs.

Sports Drinks

  • Sports drinks are offered at nearly every race

    Sports Drinks: Another popular method of fueling is using sports drinks. You can buy readymade drinks or powders that you mix on your own. The amount of calories per serving in your drink will depend on how much water you mix the powder with. It’s wise to follow the package directions because the osmolality of the carbohydrate solution is important in how it is assimilated into your body. If you choose to mix the powder thicker than recommended make sure you take it with water. Osmolality is basically the concentration of dissolved particles in your blood plasma. The higher the concentration of your carb source, the higher the osmolality. A product with a high osmolality will take longer to leave your stomach and intestines (during which time it’s not being made available to your muscles). Most races will provide sports drink at nearly every aid station. If you plan on taking advantage of this for your fueling it would be wise to practice with it in advance. If you choose to carry your own sports drink to fuel with make sure that you’ve practiced carrying the amount you’ll need for the race. Some people choose hand held bottles, waist packs, and hydration backpacks. Many larger marathons don’t allow hydration packs so be sure to take that into account when you’re planning your fueling.

Combination Products

  • Generation Ucan is our fuel of choice

    There are some products that contain a combination of carbohydrates and protein. Including some protein in your fuel plan helps the body avoid breaking down as much muscle during long distance efforts. A few combination products that come to mind include UCAN Performance Energy with protein, Hammer Perpetuem, UCAN snack bars, and many other energy bars. Energy bars typically have a high percentage of carbs, some protein, and minimal fat. They usually contain around 200 calories and have a more substantial consistency. Many people find that eating bars can disrupt their rhythm, require more space to carry, and may present digestion problems. You’ll also want to follow your bit of a bar with some type of fluid to help wash it down. If you choose to fuel with an energy bar of some kind be sure to take the total number of calories it contains into consideration. If it contains 200 calorie and you only need 150 calories per hour you’ll want to divide the bar and eat it in smaller portions. Eating 1/3 to 1/2 of the bar at a time also allows more time for the body to digest the calories it takes in.

“Real” Food

  • Many runners like to steer clear of more highly processed fuels and rely on real food options. Some of these may include: baked sweet potato, baked salted potatoes, rice balls, baby food pouches (applesauce, fruit sauces), nut butters, honey, maple syrup, flat pop/soda, trail mix, cheese, bacon, bananas, peanut butter and jelly sandwiches, dried fruit, candy, pretzels, etc.. A possible disadvantage of real food during running is that it often has a higher amount of fiber and fat and this many cause stomach upset. If you choose to use real food be sure to practice, practice, and practice. You don’t want to get in the middle of a race and have your stomach rebel. During races there are often “unofficial” aid stations set up with everything from beer and pretzels to pickles and candy. Unless you have an iron stomach, have practiced with these foods, or are running at a very easy pace be very careful about trying anything new on race day.


Post Run Fueling:

Proper fueling doesn’t stop when you’re done running. What you do in the post-run period is also very important. Make sure that you begin the refueling process with some protein and carbs within 30 minutes after your run. This is the optimum window of time that your body refills your muscles glycogen stores and starts repairing muscle. In other words, the time to carb-load is now.

You can train your muscles to store extra glycogen by faithfully refueling during this time period. Many experts recommend using a 3-1 carbohydrate to protein ratio for refueling. For women the hormone progesterone can increase muscle breakdown. Women should be getting in at least 25-30 grams of protein with our carbohydrates within 30 minutes post-long run or strength workout. There are many different types of recovery products out there to try or you can reach for “real” food options.

Nauseated After a Run?

If you feel nauseated during or after running, try to avoid consuming too many simple sugars which can cause “dumping syndrome.” Dumping syndrome is when your body can’t absorb the amount of sugars (or fats) consumed and sends them on through quickly. If you experience regular GI upset after running, try eating bland carbs like mashed potatoes, cream of wheat with maple syrup and ginger or peppermint tea sweetened with honey. Nausea post-run can also be caused by an electrolyte imbalance so adding some electrolytes to your water is essential.

You will probably be ready to eat a more substantial meal around an hour after your long run (sometimes you may not feel hungry at first or you may even be slightly nauseated if your electrolyte levels are off). Make sure the substantial meal includes a balance of complex carbs, protein, and fat. Also, focus on maintaining hydration in the hours after running. You don’t need to guzzle water the rest of the day, but make sure that you continue to drink. If it was a hot day or you sweated a lot it can be wise to add electrolytes to your water in the post-run period.

Hitting the Wall?

If you are having trouble with “bonking or hitting the wall” at some point during your run this is probably the point where your muscle stores of glycogen get used up. You need to focus on taking in more carbohydrate calories during the recovery period (to teach your muscles to carb load) and also practice fueling during the long run. Some people wait too long before beginning their fueling strategy.

If you wait until you’re feeling weak or shaky you most likely will have trouble replenishing calories to get on top of your energy needs. Remember, long runs are for practicing and you shouldn’t be doing anything new on race day (except maybe setting a distance or time PR).

Thanks for reading/listening to this episode. I hope it helps!

Nutrition for Runners

Just a heads up that we have a whole course on Nutrition for Runners created by Coach Jennifer Giles (RD) in the Academy that includes information on optimal fueling for runners.

Here’s the other lessons inside the course:

  • Power Breakfasts for Runners
  • Eat to Run or Run to Eat?
  • Nutrient Timing and Blood Sugar Regulation
  • Fueling During Runs
  • Hydration for Runners
  • Avoiding Weight Gain
  • Recovery Nutrition for Runners
  • Nutrition and Stress Fractures
  • Smoothie Making 101

This course is included with Academy membership along with our seven out courses, access to the Training Plan Vault, Podcast Vault, and our awesome online community. Join here.

Also Mentioned in This Episode

The MTA Virtual Half Marathon. Registration now open! Check out this year’s awesome medal and hat.

Generation Ucan -the revolutionary new way for runners to fuel. UCAN keeps your blood sugar stable, is gentle on your stomach, and allows your body to burn fat. Use the promo code “MTAFUEL” to save 15% off your order. Or if you’re new to UCAN, save 25% on your first order with code MTA25”.

Roar -How to Match Your Food and Fitness to Your Female Physiology for Optimum Performance, Great Health, and a Strong, Lean Body for Life by Dr. Stacy Sims

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2 Responses to The Marathon Fueling Episode!

  1. Arianne Keller September 12, 2019 at 10:25 pm #

    This episode is GREAT. thanks for all the amazing info!!!

    • Angie Spencer September 13, 2019 at 12:08 pm #

      You’re welcome! Glad it was helpful 🙂

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