Nutrition for Marathon Training

Isn’t the body amazing? It not only can power us through a 12 hour binge of netflix but can also propel us through 26.2 miles of running! But to power your body through both of these rigorous activities, you need to nourish it differently. For the binge, I would probably recommend pizza and a soft drink to optimally help the body to enjoy the moment. But for a marathon, a bit more calculation and effort needs to be applied. Keep reading to learn more!

Let me start with a little bit of background information. Endurance exercise (for this purpose of this post) is considered exercise > 30 minutes. The body is depleted of glycogen stores at about 45 minutes of exercise, so any activity greater than this needs to be properly fueled before, during, and after. What are “glycogen stores?” This is how the body stores glucose (energy from carbohydrates) in the body. When you eat carbohydrates, they are converted into glycogen and stored in the muscle and the liver for later use. Once the body runs out of this, it starts using fat for energy. And then if this is all gone, it uses muscle (which is not wanted). This is how the body normally runs, but can be altered to be forced to use only fat (more on this later). This article will focus on a high-carb diet because that’s what the majority of research suggests as of now. Also, these recommendations are based on science, but everyone’s genetics and bodies are different. Try these suggestions but listen to your body and tweak them depending on how your body responds. Think of this as your starting point and either increase or decrease from there. 

Carbohydrates

While you are training for your run for months and months, you’ll want to focus on increasing calories mainly by increasing your carbohydrate intake. Most articles and studies that I have read suggest that eating anywhere from 5-12 g of carbohydrate per kg of body wt (1 kg= 2.2 lbs) per day. However, one study that I read suggested that this actually may not have an effect on increasing endurance. So again, adjust to what you feel that your body succeeds with. Know that as your carbohydrate intake increases, likely so will your weight because glycogen holds on to water in the body. So the weight you gain will be mostly from water weight. The day that you run, make sure to try to eat at least 2 hours before running to top off any low glycogen stores. This meal should be between 400-800 calories. The day before your race, 70% of your calories should come from carbohydrates. You can figure this out by (calories for the whole day x 0.7) / 4g. This will give you the grams of carbohydrates. Your body will adjust to this influx of carbohydrates. So if your stomach feels off in the beginning, try to ride it out. Your stomach is also going through training. 

As far as during exercise, there are many different recommendations. Some say you need carbohydrate intake if exercising more than 45 minutes and others say 60 minutes and others say 90 minutes. So again, listen to your body and when you’re starting to feel your energy decrease. It is believed that the body uses about 1 g CHO per minute during exercise, so the goal is to replace that much during exercise (1 hour run should be fueled with 60 g carbohydrates during the run). You can start fueling at 15 or 30 minutes and eat little bits at that same interval for the entirety of your run. Research suggests that eating a mixed type of carbohydrate during your run is most-easily absorbed. So many of the pre-made gels or nutrition bars are great during your run and can be super convenient. But other items such as pretzels, fig bars, and bananas are recommended as well. 

Eating carbohydrates after running is just as important and timing this can help with recovery for your next day’s run. The body absorbs the most glucose within the first hour after ending exercise. This gives you the chance to refill those glycogen stores. Try to eating 100-400 calories right after exercising. This can be achieved through gel, a liquid with carbohydrate (milk or sports drink), or any carbohydrate foods. Replenishing the body with carbohydrates may also help with decreasing muscle soreness in new athletes. 

Fluid

Being dehydrated can seriously impact performance. You lose water through sweat so that the body is able to cool. It is best to judge what you need through your urine. I recommend first starting about between 2-3 L of water per day. You want your urine to look like pale lemonade. If it’s too yellow then drink more water. If it’s too clear, then drink less. You want to make sure you limit your fluid losses by 2-3%. So make sure to try to weigh yourself before running and then after to determine if your weight has decreased by more than 3% ((weight before-weight after)/weight before). A guide is to drink 2-3 cups of water for every pound lost. 

While running, drink 8 oz of fluid any time you eat something, even a gel. This helps the food to be absorbed.

Sports drinks do have a place in endurance sports, as the body does lose some electrolytes. It is recommended to drink 10 oz of sports drink or electrolytes 2 hours before exercise lasting longer than 90 minutes. You can also drink this during your run instead of water. 

Caffeine

There is some evidence that caffeine 1 hour before running can improve performance. Recommended amount is 3-6 mg/kg. 

Tapering

When tapering in the weeks before your race, you will want to also decrease the amount of food eaten. Try to reduce your food intake by 100 kcal for every mile removed from training. Focus on filling up on lower calorie foods just as fruits and vegetables. 

Fat & Protein

Protein will help build your muscle, so you will also need to make sure that you are eating enough of this. Focus on protein after your runs and not so much before. Protein can slow digestion which can cause stomach discomfort during your run. 1.2-1.4g per kg of body weight is the recommended amount (per day). Fat is also needed for many other bodily functions. However, as carbohydrates are most important that doesn’t leave too much room for fat in the diet. 20%-35% of calories should come from fat. This can be calculated by: (total calories for the day x .2 or .35)/ 9. This gives you the total grams of fat per day. 

What if I’m keto??

So I didn’t do too much digging, because I feel like that could have been a whole separate blog post. But yes! It’s possible! There are lots of studies on athletes performing well on a keto diet. The key is that your body must be in ketosis though, so it switches to burning fat instead of glycogen. If you’re not in ketosis it will just try to burn what little glucose you have given your body. Not much research has found that this will make you perform any better, but if this is the way you enjoy eating, then you can still train like this! It is definitely a very interesting topic to dive into. 

Example Full Day of Eating (High Carb) 2396 calories, 104 g protein, 360 g carbohydrates, 63 g fat

Breakfast: 4 pancakes with syrup, coffee with cream and sugar, 1/2 cup strawberries

During workout: gu pack

Post-Workout: peanut butter and jelly sandwich on white bread

Lunch: 2 cups whole grain pasta with marinara sauce and parmesan cheese, green beans

Snack: smoothie with spinach, 1 TBS almond butter, 1 TBS greek yogurt, and banana

Dinner: 4 oz chicken breast, 1/2 cup quinoa, large Cesar salad

Sources:

https://www.tandfonline.com/doi/full/10.1080/02640414.2011.610348

https://journals.humankinetics.com/view/journals/ijsnem/23/2/article-p170.xml

https://journals.lww.com/acsm-csmr/Fulltext/2008/07000/Recovery_Nutrition__Timing_and_Composition_after.7.aspx?casa_token=egC1pfN85LQAAAAA:xUPpbw3bTRhGZnAJHkF4HrDMBPfJ2cSkU0RgufL1hoc83tZn8WO_1FLmH7HMslofIRtvMvL94yhi5nc6a9YMx0M

https://www.todaysdietitian.com/newarchives/030810p36.shtml

https://www.theactivetimes.com/run-race/road/runner-s-ultimate-guide-marathon-training-nutrition

https://www.dietitianonthemove.ca/blog/eating-for-endurance

https://www.runnersworld.com/advanced/a20790367/real-runner-nutrition/

https://journals.physiology.org/doi/abs/10.1152/jappl.1984.56.1.78

https://journals.humankinetics.com/view/journals/ijsnem/15/1/article-p1.xml

https://link.springer.com/article/10.1007/BF00392032