Five Basic Principles of Nutrition for Runners

Nutrition for Runners

Nutrition for runners can feel overwhelming at times. Sports nutrition recommendations differ from general nutrition guidelines. Fad diets circulate and some social media influencers present misinformation. How do you know if your diet is supporting your running? Nothing can replace working with a credentialed professional such as a registered dietitian. However, these five basic principles of nutrition for runners can serve as a starting point. 

1. Scale Carbohydrate Intake Based on Training Volume

Runners require carbohydrates in their diet. If you run more than a couple of 30-45 minute runs per week, you need more carbohydrates than the average person does. Carbohydrates are a vital source of energy production for any intensity of running. 

Additionally, carbohydrates support immune cell function, brain function, and endocrine system function (amongst other body functions). Carbohydrates have a complex interaction with micronutrient absorption. Carbohydrates, especially whole grains, contain many essential micronutrients. Chronically low carbohydrate intake can upregulate hepcidin, which blocks iron absorption. (See this 2019 review in the European Journal of Applied Physiology). The fiber found in carbohydrates such as fruits, vegetables, and whole grains aids in digestive health. Fiber also lowers the risk of various diseases.  

However, your carbohydrate needs as a runner are not static. If you are training for a marathon, you need more carbohydrates than if you are running low mileage. Most runners change their training focus throughout the year. With each training cycle, off-season, and base-building phase, you want to scale your carbohydrate needs to support your training volume. The more you run, the more carbohydrates your body needs. 

On a micro-scale, this means adjusting your carbohydrate intake for easy, moderate, and hard training days. For example, you will eat more carbohydrates on a long run day compared to a recovery run day. On a macro scale, you eat more carbohydrates in high-volume peak training compared to off-season training. 

Carbohydrate choices can also be modified based on training load. When you are in a low-volume phase, you may choose more fruits and vegetables for carbohydrate sources. When your training requires high carbohydrate intake, you will likely include low-fiber, simple carbohydrates. Low-fiber carbohydrates can help meet daily goals without overdoing fiber. Additionally, high-volume athletes will eat more simple carbohydrates before, during, and after runs to support those training sessions. 

The same principle applies to protein and fat intake. Every runner has a baseline requirement for those macronutrients. As training volume increases, protein and fat intake should both increase. 

A simple guide to carbohydrate intake:

  • Light (30-50 min, a few runs per week): 3-5 grams per kilogram of bodyweight
  • Moderate: (~1 hour per day, several days per week): 5-7 grams per kilogram of bodyweight
  • High: (1.5-3 hours per day): 6-10 grams per kilogram of bodyweight
  • Heavy (>3 hours per day): 8-12 grams per kilogram of bodyweight

You will notice that these are wide ranges. Adapt within the range to find what feels best for you! Your needs may fluctuate daily. Some runners find they feel best with more fat in their diet, so they may eat carbs on the lower end of recommendations. (However, unless guided by a registered dietitian, stay within the recommended range due to risks of low carbohydrate diets and overtraining and endocrine dysfunction), Others thrive with more carbs on the higher end of the recommendations.

A simple way to visualize carbohydrate periodization is the Athlete’s Plate. The Athlete’s Plate provides a visual representation of how your plate should look based on your training volume. Easy days are <60 minutes; moderate days are 1-2 hours (across one or multiple workouts); and hard days more than two hours (across one or multiple workouts). 

2. Eat Enough for Your Training Load

Undereating disrupts endocrine function in both male and female runners. When undereating occurs on a long enough scale, an athlete can develop relative energy deficiency in sport (RED-S). 

Signs of undereating include loss of menstrual period (amenorrhea), libido loss, sleep disturbances, mood changes (including irritability), frequent soreness, frequent muscle pain/cramping, fatigue, and intense cravings. When undereating builds into RED-S, performance will decline. You are left with poor recovery, low energy in training, and increasing slower training and racing paces. 

Undereating is linked to overtraining, according to a 2022 review in Sports Medicine. As outlined in this review, low energy availability and low carbohydrate intake are associated with overtraining symptoms across several studies. Additionally, overtraining symptoms often overlap with symptoms of RED-S, suggesting a link between the two.  

Eating enough for your training load not only mitigates negative outcomes such as amenorrhea and injury; it also promotes training adaptations and supports performance. A well-fed athlete has the energy to perform to their potential. An underfed athlete may struggle with fatigue and have poor training quality, which leads to diminished training adaptations over time. 

Eating enough for your training load means eating all three macronutrients. The higher your training volume, the more carbohydrates you need for energy production, the more protein you need for muscle repair, and the more fat you need for cellular and endocrine function. Additionally, eating enough for your training load helps you consume enough micronutrients (including antioxidants) to support your body’s recovery needs. 

3. Eat a Variety of Colorful Fruits and Vegetables

A wide variety of fruits and vegetables supports micronutrient requirements. For example, leafy greens provide vitamin K. Bell peppers and berries provide vitamins C and E. Bananas supply potassium. Carrots and sweet potatoes provide vitamin A. Variety is key!

The antioxidants in fruits and vegetables are very beneficial for runners. The antioxidants include vitamins C, E, A, zinc, and various other compounds found in foods. Antioxidants reduce the oxidative stress that we accumulate as a natural result of training. While oxidative stress is essential for adaptation, too much can be detrimental. Antioxidants scavenge free radicals and reactive oxygen species. Additionally, antioxidant consumption may reduce delayed-onset muscle soreness, according to a 2020 review in Redox Biology

It is worth noting that the evidence is not clear on whether antioxidant supplementation (which often has vitamin mega-doses) blunts training adaptations. Additionally, some recent studies suggest that excessive antioxidant consumption may actually turn the antioxidant into a pro-oxidant, thus increasing oxidative stress. Given that evidence, it is safest to rely on five to nine daily servings of vegetables and fruits for antioxidants. 

For most runners, an appropriate goal is a minimum of five servings of fruits and vegetables per day. You can eat more. However, be mindful that you are not filling up excessively on vegetables and fruits at the expense of other foods. (Additionally, too many fruits and vegetables can lead to very high fiber intake, which can cause gastrointestinal distress in some runners.) 

Fruits and vegetables alone will not provide all the vitamins and minerals you need. Be mindful to include other foods in your diet. Legumes and red meat provide iron. Dairy or fortified dairy substitutes supply calcium and vitamin D. Many nuts and seeds offer a plethora of micronutrients, including vitamin E and magnesium. Unless you have medical reasons, eat from each food group and eat a colorful variety of fruits and vegetables.

4. Fuel Your Training for the Work Required

One of the primary goals of sports nutrition is to support performance via nutritional interventions. For long-distance runners, taking in supplemental carbohydrates during long runs or hard workouts supports performance. As outlined in the seminal 2014 review in Sports Medicine, carbohydrate intake during long runs should be scaled based on the duration. The longer the effort, the more muscle glycogen you will use, and the more exogenous (from food or supplement) carbohydrates you will need. 

Fueling for the work required means that you adjust your carbohydrate needs to support the given effort. On shorter easy runs (<60-80 min), you do not need any carbohydrates due to the length of the session. These runs allow your body to improve fat oxidation rates. On medium-length efforts, you take enough carbohydrates to ensure adequate energy, but not so much that your gut feels overwhelmed. On very long efforts, extreme fueling approaches (as outlined in this Trail Runner Magazine article) support the extreme energy demands.

Additionally, fueling on long runs enhances recovery. I often see runners report that they no longer feel exhausted after their weekend long runs once they start fueling appropriately. This is demonstrated in the evidence repeatedly. In this 2020 study in Nutrients that saw higher intra-run carbohydrate intakes associated with better markers of muscular recovery in mountain runners. 

How to Fuel Your Runs:

  • Easy runs <80-90min: no fuel required (can bring sports drink for hydration)
  • Hard workouts <90 min: sports drink for hydration and carbs
  • Runs (any intensity) 1.5-2.5 hours: 30-60 grams of carbohydrate per hour
  • Runs (any intensity) >2.5 hours: 60-90 grams of carbohydrate per hour

Carbohydrates during long runs can come from a single type of sports nutrition or a combination. I recommend combining (such as gels and sports drinks) when you are aiming for 50 or more grams of carbohydrates per hour. (If these amounts sound daunting, listen to this episode of the Tread Lightly Podcast for practical guidance on how to actually eat that much during a run!)

The evidence simply is not strong enough to support fasted running and withholding carbohydrates on long runs. Female athletes are particularly prone to negative ramifications of energy restriction around exercise. However, male athletes are not immune to these ill effects. (Read here for more on fasted running and here on low-carbohydrate training.) 

5. Supplement Cautiously and Deliberately 

Supplements are not the magic bullet that social media presents them as. You won’t magically get faster from taking the newest supplement, even if another runner attributes their PR to it. Supplements are complex: each has its risks and not all contain what their labels claim. Additionally, supplements can interact with other supplements and medications. 

That all said, not every athlete can meet their adequate micronutrient intake through food alone. For those athletes, supplements play a crucial role in supporting both performance and health. Additionally, some supplements (such as caffeine and sports drinks) have clear evidence supporting their benefits. 

Certain micronutrient supplements (such as iron) should be taken only if bloodwork indicates a need. Vitamin toxicity is rare but can occur; even elevated levels of certain micronutrients can be detrimental. In the example of iron, high ferritin levels can produce similar symptoms to low iron levels, such as fatigue. 

Every athlete can benefit from routine bloodwork to assess deficiencies and appropriate micronutrient supplementation. If you have been recently injured (especially with a bone stress injury) or feel tired often in training, you may want to have bloodwork done. 

Performance supplements, such as pre-workout, creatine, and protein powder, should be taken based on individual needs. You may benefit from them. Or, they may be a waste of money, depending on many factors.

For every supplement that you consider taking, perform a risk-reward analysis:
  • What are the ingredients?
  • Will this interact with any medications or other supplements you are taking?
  • Does my bloodwork indicate I need this supplement?
  • What are the benefits of this supplement for my specific goals?
  • How strong is the evidence supporting the benefits of this supplement?
  • Can I achieve the benefits through dietary changes?
  • Is this supplement third-party tested? 
  • What are the risks to taking this supplement (including acute adverse reactions and chronic risks)?

Effective Sport Supplements for Runners

Caffeine is one of the safest and most effective supplements for runners. However, it does not work for everyone. Some runners tolerate caffeine well. Others find it causes side effects such as anxiety, GI upset, jitters, or palpitations. If you do supplement caffeine, it is most effective before a workout or during a long run/race. Many gels and sports drinks contain caffeine for easy supplementation during runs. Before a run, you can use coffee, tea, or a pre-workout supplement. However, if using pre-workout, check the ingredients to see what it contains. Many pre-workout supplements are multi-ingredient, and not all ingredients benefit runners. 

Other performance supplements, such as creatine, may or may not benefit runners. The overwhelming consensus from the research is that creatine is safe and highly effective for increasing muscle mass. For long-distance runners, the performance benefits are presently unclear unless your goal is to increase muscle mass. (For more information on creatine for runners, reference this article.) 

After completing several graduate-level classes in sports nutrition, the supplements I recommend are:

If in doubt, work with a certified sports nutritionist or registered dietitian on supplements. Always assess your supplement intake as a whole, to avoid accidentally taking too much of any given vitamin or mineral. (For example, too much supplemental magnesium can cause diarrhea.)

Disclaimer: I have an MS in Applied Exercise Science with a concentration in Sports Nutrition and am an ISSN-certified sports nutritionist. However, I am not a registered dietitian. This article presents general advice, not individualized advice.

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33 Responses

  1. Wow I really love all of these so much, because there is so much balance. I think that diets often tend to get us focused on ‘extremes’, but these tips remind the runner that it’s all about balance. 🙂 And usually even though I like some simple carbs, complex carbs do keep me much fuller!

  2. I definitely agree with these guidelines. Sticking to unprocessed food and making sure you get enough fruits and vegetables is a good place to start I think! I definitely struggle to get enough protein without eating meat so I always eat it at least once a day.

    1. Thank you! I do think it is hard to get enough protein – and enough heme iron because that’s not found in plants – without eating meat at least a few times a week. I’ve tried vegetarianism and it just is too difficult to get enough.

  3. For years I was a pretty strict vegetarian, some days vegan. But then I started playing around with eating a little meat here and there and found I felt better. Every body is different so you need to find what works for you. Great tips!

  4. I never thought I would go meatless but when it happened, I felt so many wonderful benefits, especially when it came to running! I don’t know if I will always be this way but the thought of chicken grosses me out now so maybe lol. I now want those roasted potato wedges I spotted on your plate with the salad. they look so crispy and good! I know what’s for dinner tonight!

    1. I bake my oven fries (with a healthy dose of olive oil, garlic powder, and sea salt) at 425 for 30-35 minutes and then broil them for 5 minutes to make them crispy – they’re so good! Lol I can manage chicken but I don’t do much to it – funny enough I find that the more I handle meat, the less gross it is.

  5. I couldn’t put it better myself. I think the one/two point(s) that I would add would be a) refuel with a mix of carbs and protein and b) don’t eat all of your calories at once. I find all too often that people are just like REPLACE ALL THE CALORIES after a run!

    1. Thank you! I agree with both of those points. The body can only take in some many calories at once, and while you don’t want to skimp on that post run meal, spread the calories throughout the day!

  6. Oooh Number one. I saw this so very frequently when I owned my training studio. These were more weekend warrior athletes – – but there was still applies. It never ever helps.


  7. Yes to ALL of this and especially #4! If it’s not sustainable over the long term, it will not work. As for my personal diet, I always have to work harder to include my veggies. I can eat a truckload of fruits but sometimes have to force more servings of vegetables 🙂 Although summer is a lot easier with all the corn, squash and fresh tomatoes!

    1. Thank you! Lots of fruit taste so good after a run – especially summer fruits like berries. Vegetables are hard to get in – although I agree, summer vegetables are better! And fall with all of the squash.

  8. Six to NINE servings of fruits and veggies PER DAY?! Not month? Lol… I AM SO SCREWED. I’ve definitely nailed down the first point though… heh heh…. 😉

  9. This serves as a great reminder that I need (and want) to get more fruits and veggies into our diet at home. Sometimes the choices at the store just look so “blah”. I really wish there were more local fruit & veggie stands around this area. I feel like it would make it so much easier for me to keep up on what I want to have at home….(yes…I know that is just an excuse)….

    1. Really? I’ve found that the produce in the grocery stores and markets here is so much fresher than it was back in the Midwest. Vegetables aren’t supposed to look perfect – spots and weird shapes are normal and good (too perfect looking of fruit/veggies can mean too much genetic modification). Local stands are great as well, but the stuff at the groceries stores is good and often local around here – I love all the fresh local berries and apples right now!

  10. So true! I think it’s so important for runners to realize that carbs, especially, are vital for our fuel. Our performance is determined by what we eat! I would also add the nutrient-dense snacks are encouraged. Not only are they a great way to bridge the gap between the next meal, but they also offer the opportunity to get in more nutrients to fuel our previous or next run!

    1. I agree! When I work with runners it amazes me how many are still a little afraid of carbs or calories – but nutrition has just as much of an impact on performance as training does! Nutrient snacks are another great tip – and a great chance to sneak in more fruits and vegetables!

  11. This is such great, balanced advice! I completely agree. Everyone wants a specific “diet” or guidelines to follow when what actually works best is a little bit of freedom… eating what your body wants, aiming for high quality choices from real food as much as possible.

  12. You always have such great advice <3 I feel like #1 is especially important since most people don't seem to realize how much their bodies actually need to function optimally instead of just barely getting by. Cutting too many calories will always come back to kick you in the butt since you won't have as much energy to be active, and therefore not end up burning as much. Besides… food is just way too good 😆

    1. Awww, thank you, Amanda! I agree – cutting calories may be great for being model thin but you simply can’t function well like that. And also…food is just too good!

  13. Thank you for this wonderful post…I didn’t realize how easy it was to lose muscle/body mass while training the long miles for my last marathon…I needed to substantially increase my calories, and by not doing that, I found myself 5 lbs. underweight, weak and out of synch. This post is a wonderful reminder: Good nutrition and an increased bump in calorie consumption are key to staying healthy, strong and race ready.

    1. It is easy to lose muscle mass. Without eating enough calories, the body will actually catabolize muscle to help repair after a run. Good nutrition includes eating enough calories for runners!

  14. Thanks for the nice clear guidance. I’d be interested in your opinion on artificial sweeteners in electrolyte/sports drinks. The evidence that some sweeteners have adverse effects on the microbiome has caused me to throw out a recent purchase because it contained sucralose.

    1. Thank you for commenting! The interaction of non-nutritive sweeteners and gut microbiome is very complex and not fully understood – the research is still fleshing it out. Richardson & Frese (2022) provide a review on this. Essentially, there may be individuals who have negative outcomes, while other individuals may not or may even benefit (in cases of reducing caloric intake). So, then it comes down to the context of non-nutritive sweeteners in sports drinks. The sugars in sports drink provide easily-digestible glucose for quick energy on runs; sucralose and non-nutritive sweeteners simply do offer any benefit for energy production since artificial sweeteners (by definition) do not provide glucose/carbohydrates. Some athletes find artificial sweeteners also cause GI upset. So generally, I encourage athletes to choose sports drinks with real sugars (glucose, dextrose, maltodextrin) to have the energy benefits.

  15. Thanks for picking up on this and replying so promptly. Yes, that’s pretty much as I thought…the ones I threw out were intended to supply electrolytes, and flavour, but no calories. I bought them just before the recent research results on sweeteners and the gut microbiome hit the press around the end of 2022. I decided, in all conscience, I couldn’t even give them away.

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