Marathon Nutrition Guide

Summer is rapidly approaching, which for many of my friends and clients means the start of Fall marathon training. Please find below my comprehensive Marathon Nutrition Guide to help you get to the start and finish line healthy and strong!

Marathon Nutrition Guide

Marathon runners often focus heavily on their training but neglect their nutrition, which can have a significant impact on their health and fitness goals. Perhaps you can get away with just “winging it” during shorter training runs and races, but the marathon is another story. Whatever your goals may be as you embark on your training program – achieving a specific time, just finishing the race, losing weight, etc. – you need a tried and tested nutrition plan to help you cross the finish line injury-free and feeling strong!

Building Your Nutrition Base

When you think about marathon nutrition, you may conjure up images of gels, chews, protein bars, electrolyte drinks, and lots of pasta. Sports nutrition products and carb-rich foods certainly have an important place in training, but you also must take a careful look at your every day eating patterns to ensure you are fueling optimally for overall health and performance. Consistent good nutrition – what you consume throughout the day, as well as just before, during, and right after exercise – forms the base of a successful sports nutrition diet.

Balancing the Macro- and Micronutrients

Eating for endurance requires more than simply consuming enough calories to offset all the energy that you are burning through exercise. You have to make sure those calories are coming from the right food sources and in sufficient quantities to feel satisfied, stay healthy, and fuel and recover well while increasing your mileage.

Carbohydrates are needed in the greatest amount, as they break down into glucose (sugar) to give us energy. Carbs are the body’s preferred fuel source, especially during moderate and high intensity exercise, when oxygen is less available. Any glucose that isn’t used right away is stored as glycogen in the muscle and liver and broken down later when needed, for example during sleep and exercise. These stores are limited, so you have to eat enough carbs regularly to stay well-fueled and preserve your lean body mass, especially on heavy training days.

  • Good sources: Carbs that provide additional nutrients, such as whole grains, starchy veggies, fruits, beans/legumes, and low-fat/full-fat dairy

  • Note: Simple carbs like white rice, plain pasta, sports nutrition products etc. are more easily digested and may be better tolerated right before exercise

Fat also provides energy but less efficiently, as it requires greater amounts of oxygen to break down. As a result, the body relies upon fat more heavily as a fuel source during lower intensity exercise. Fat stores are unlimited, with even the leanest athlete having tens of thousands of fat calories available to burn! Fat keeps you fuller longer and certain fats (omega-3’s) help fight inflammation – both crucial during training. However, be cautious about consuming fat right before or during exercise. Although you can train your body to tolerate some fat and become more efficient at burning it, fat slows down digestion and may cause gastro-intestinal distress.

  • Good sources: Unsaturated fats, such as olive oil, avocado, nuts/seeds, fatty fish, and portion controlled amounts of saturated fat from coconut and dairy

Protein is needed to build and repair body tissues, especially during heavy training. Endurance athletes need to eat more protein than the average person, ideally between 1.4 to 1.8 grams of protein per kilogram of bodyweight. Include protein as part of all meals and snacks to feel satisfied and optimize ongoing recovery.

  • Good sources: Real foods such as lean meat, fish, poultry, beans/legumes, low-fat/full-fat dairy, whole eggs, nuts, and organic soy (tofu, tempeh, edamame)

Vitamins & minerals support growth, tissue repair, oxygen transport, and energy metabolism. While all micronutrients play key roles in the body, adequate amounts of iron and calcium are particularly important in maintaining health among athletes. Unless you have a valid reason to take supplements – for example, you follow a restrictive diet, have a known deficiency, are pregnant, etc. – eating real food is better than taking supplements.

  • Good sources: A variety of nutrient dense foods (colorful fruits/vegetables, whole grains, nuts/seeds, different protein sources) to obtain a wide range of vitamins and minerals

Generally speaking, try to create nutritionally balanced meals and snacks to support your training (what you eat right before and during runs will skew more towards carbs). For example, rather than eating two pieces of whole-wheat toast with mashed avocado for breakfast, put some eggs on top to include a high quality protein source. Similarly, instead of having a banana as an afternoon snack, add some almonds, peanut butter, or Greek yogurt for a dose of healthy fat and fiber.

Weight Management & Marathon Training

Many runners are concerned about their weight during training, as they deal with changes in appetite, a desire to achieve racing weight to optimize speed, etc. Many of you surely have had a long run or two that ended in binge watching TV on the couch all day and eating nonstop! If weight loss is your goal, proceed carefully and remember that consistent under-fueling increases risk of injury and illness. Weight loss can be achieved, however, while keeping these tips in mind:

  • There’s no such thing as a healthy short cut, so forget about those fad diets. Behavior change, consistency, and portion control are key to long-term success.

  • Aim for balanced meals and snacks with a variety of foods. Portion control starchy foods (especially on lighter training days), eat adequate protein and calories to preserve your lean body mass, and don’t fear fat – it’s your friend!

  • Practice mindful eating: Always ask yourself, are you eating because you’re hungry or for another reason? Eat slowly and without distractions.

  • Load your plate up with non-starchy vegetables and avoid skipping meals, which may lead to overeating later.

  • Keep a food/training diary to keep track of what you’re eating and how you’re feeling during workouts to identify areas of improvement.

  • Don’t deprive yourself! You are marathon training, after all. Plan to have some treats once in awhile (the real thing, not some “healthier” version), and leave the guilt behind.

Creating Your Unique Marathon Nutrition Plan

There are many factors that go into creating a successful marathon nutrition plan, and it takes some trial and error to figure out what works best for you in the context of your specific event. Although there is no one-size-fits-all approach, these three general sports nutrition principles should guide you in creating a nutrition plan that meets your unique nutrient needs, taste preferences, and tolerances: stay hydrated, provide fuel for your muscles, and promote optimal recovery after exercise.

Begin experimenting with various nutrition strategies early in your training cycle, so that you have plenty of time to test them out during your long runs and training races. As everyone always says, nothing new on race day! Do your homework and find out which types of sports nutrition products your race offers on the course, and how frequently you will encounter aid stations. Try to simulate your race environment by either training with these same products, or figuring out the logistics of comfortably running with your own nutrition and/or hydration. By the time you begin your taper, you should know what you plan to eat the day before, morning of, and during your marathon, with room for flexibility in case game-day tweaks become necessary (e.g. extreme weather conditions).

Hydration: Fluids & Electrolytes

During exercise, you lose water through sweat and breathing, increasing your risk of dehydration and making it essential to hydrate before, during, and after a workout. On the other end of the spectrum, over-hydration (hyponatremia) can occur with serious consequences if you only drink plain water during endurance activities and do not replenish electrolytes (i.e. salts, including sodium, potassium, and chloride) that are lost in sweat. Heavier, slower runners with high sweat rates who run for many hours are at greatest risk. With the dangers of over-hydration in mind, guidelines have changed from staying ahead of thirst and drinking as much as you can tolerate to paying more attention to thirst and replenishing 100% of fluids lost in sweat.

Sweat rates are highly individual and change in different weather conditions. Monitor your hydration status day-to-day with the “pee test,” aiming for pale-colored urine. You can more accurately measure your sweat rate by performing a sweat test. Weigh yourself before and after a run, keeping track of how much fluid you consume in between. Each pound that you lose equates to 16 oz (2 cups) of sweat, and should be replenished. For example, if you lose three pounds (6 cups of sweat) and drank 2 cups of water or sports drink during your hour-long run, then your sweat rate is 8 cups per hour and you should drink 6-8 cups of fluid as part of your recovery.

Before: Don’t leave hydration to the last minute! You should be consuming adequate fluids throughout the day, not just the hour before your workout.

  • Carry a large water bottle around with you and aim to refill several times each day.

  • Plan and practice your pre-race hydration strategy before long runs.

  • Drink the bulk of your fluids with breakfast 2-4 hours beforehand, and sip 6-8 oz of fluid one hour before, to avoid having to run to the bathroom.

  • It’s natural to feel an urge to pee as you nervously await your start time. It takes about 60 minutes for any fluid you consume to make it to the bladder, so any fluids you consume right before the start will be immediately used/converted to sweat.

During: Aim to replenish the amount of fluid that you are losing.

  • Plain water usually is adequate for easy runs and cross-training efforts <60-90 minutes.

  • If it is hot out and/or you are a heavy sweater, you may also require electrolytes during shorter workouts. Salt pills (e.g. SaltStick), tabs that you dissolve in your water (e.g. Nuun), or water with added electrolytes (e.g. Propel) are options.

  • During long runs and races, be sure to consume electrolytes. Your carb source (gels, sports drink, etc.) may be adequate, or you may need more (e.g. salt pills), but don’t overdo it.

  • Many runners only drink 2 or 3 oz of fluid (or less!) per aid station. Practice drinking similar amounts from a bottle during training to see if this is adequate for you, and be prepared to adjust your plan if weather conditions vary.

After: Rehydrate within 30-60 minutes after exercise with both fluids and salts as determined by the sweat test or by using the “pee test.”

  • Electrolyte replacement drinks and other sports products are convenient but not necessary. Real food contains salts too, and when consumed with water, is adequate for recovery!

Fueling Before Exercise: General Rules

What you eat and when before exercising depends on how much time you have and what you are seeking to do. Are you training in the early morning or later in the day? Are you running 20 miles, doing a hard spin class, or going out for a recovery run? Do you have a sensitive stomach or can you eat and immediately run out the door? Generally, the more time you have, the more you can eat, and the more types of nutrients you can include, and the less time you have, the more important it is to choose easily digestible carbs that quickly deliver glucose to your tissues.

Research supports starting exercise with fully loaded glycogen stores to improve energy levels and optimize performance. Including carb-rich foods in your pre-workout meal or snack is especially important before hard or long efforts and before all races to prolong your glycogen stores and delay the onset of fatigue. If eating fiber causes stomach upset before exercise, avoid whole grain products (e.g. whole wheat toast, brown rice, etc.) and high-fiber fruits and vegetables, and opt for simple carbs instead. High fat and protein-rich foods are not necessary before exercise unless you prefer and tolerate them, as they slow digestion and may cause gastro-intestinal distress.

Tips for fueling before exercise:

  • For short morning workouts (<60 minutes), it’s fine to run on empty and eat after. If the workout is hard, you may benefit from a pre-exercise snack. Try and see how you feel.

  • Eat breakfast, or at least a carb-rich snack, before longer efforts (>90 minutes). Many runners prefer to eat 3+ hours before exercise to fully digest and have time to use the bathroom, but 2 hours may be sufficient.

  • For workouts later in the day, eat a balanced meal 2-4 hours before, and a carb-rich snack 1-2 hours before (e.g. toast with peanut butter). You may include some fiber, fat, and/or protein in your snack, as tolerated.

  • If you have <60 minutes to eat, choose easily digestible carbs (e.g. banana).

  • Eat before all races, regardless of distance, to perform your best.

  • You may tolerate certain foods better or can eat closer to a workout when doing a spin class compared to a run, as cycling jostles the stomach less than running does.

Fueling Before the Marathon

The notion of “carbo-loading” is outdated and there is no need to stuff your face with huge quantities of food in the days leading up to your race. Instead, just make sure that a higher percentage of your calories is coming from carbs, at the expense of protein and fat. What you eat will vary greatly based on your energy needs, food preferences, and tolerance. You may find it helpful to reduce your overall fiber intake for the day or two before your race if you are sensitive to it, although be careful not to go so low that you become constipated as a result.

Plan and practice what to eat the day before and especially the night before the marathon. Breakfast can be the same as your pre-race breakfast (see below). Lunch should be your largest meal and nutritionally balanced (e.g. salmon with a good portion of rice or baked potato and a side of lower fiber veg), with dinner slightly lighter and more skewed towards carbs with something salty to stimulate thirst (e.g. plain pasta with sautéed mushrooms, olive oil and parmesan cheese). A palm-sized serving of protein with dinner is fine, but not necessary.

Your pre-race breakfast is your most important meal, as it loads up your glycogen stores for the many miles ahead. It can be challenging on the weekends to get out of bed extra early to eat, but it’s necessary to practice at least a few times before your longest training runs to make sure you tolerate your meal of choice and perform well. Aim to eat 2-4 hours before to allow plenty of time to digest and use the bathroom. Popular choices include a bagel or toast with peanut butter and jelly, waffles with maple syrup, and a bowl of oatmeal with banana. You may also wish to have a banana, gel, some chews, or sports drink 5-15 minutes before the start, especially if you ate breakfast 3-4 hours before. Make sure you practice this during training!

Lastly, don't forget about logistics - will you be eating your meals in a restaurant or can you cook for yourself? Can you eat breakfast in your hotel or at home or do you need to bring it with you? When do you lose access to the bathroom at the race start? Plan ahead – don’t wing it! If you are traveling, many hotels have microwaves, toasters etc. and are happy to let you use them so that you can prep your pre-race meals. Don't be shy in asking for what you need!

Fueling During Exercise

Consuming carbs while running maintains blood sugar levels and prolongs your limited glycogen stores. If you don’t take in enough carbs during moderate and high intensity exercise, your stores eventually become depleted, your blood sugar drops, and you are forced to slow or stop. This is otherwise known as bonking, and it’s hard to make a comeback.

Fueling on the run can be challenging, especially during endurance events. The digestive process becomes compromised to support the energy needs of running, as oxygen-rich blood is diverted away from the gut and other internal organs and sent to the larger exercising muscles so that they can sustain activity. The harder we run, the more these muscles demand greater amounts of blood, which means that digestion can become difficult. You must experiment during training to figure out what and how much your stomach can tolerate as well as the logistics of how to comfortably carry what you plan to consume over the course of several hours.

Most runners should aim to take in 30-60g (120-240 calories) of carbs per hour during exercise lasting 2-4 hours, along with fluids and electrolytes. For reference, one gel is ~30g carbs, which translates to approximately one gel every 30-45 minutes. For events longer than 4 hours, you may benefit from 60-90g of carbohydrate, as practiced and tolerated. If you struggle with gastro-intestinal issues, don’t get discouraged – you can train your gut to improve your tolerance by regularly practicing with your chosen fuel source.

Tips for fueling on the run:

  • Begin experimenting with a variety of brands and products (gels, chews, sports drink, bars) at the start of your training cycle to figure out what works for you. One gel, 4-5 chews, and 2 cups of sports drink typically have around 30g of carbs.

  • If you can stomach and prefer real food, go for it! One banana, 2-3 medjool dates, and 6-8 pretzels each provide around 30g of carbs. Just be aware that you may still need to take an electrolyte supplement if only consuming real food.

  • Consider using caffeine to boost performance, if tolerated. Research supports using 3-6mg per kg of body weight, with caffeinated gels typically having 25-50mg each. Allow 30-60 minutes to feel the effects of any caffeinated products you consume.

  • Start fueling early in your training run or race and don’t fall behind.

  • Plan your race nutrition strategy by time, not mileage to consume carbs on a schedule. For example, take a gel 15 min before the race, then at 0:30, 1:15, 2:00, etc.

  • Listen to your body and remain flexible with your nutrition plan, especially in extreme weather conditions. For example, hot weather reduces appetite as well as nutrient absorption, making it more difficult to get the energy that you need to perform well.

Fueling After Exercise

Recovery should be high priority for all runners, especially those training for a marathon. Training and racing deplete glycogen stores, damage muscle tissue, and stimulate muscles to adapt to training workload, while recovery through rest and nutrition facilitates muscle recovery and growth, decreases risk of injury and illness, and prepares you for your next workout or race.

Nutritionally, the recovery process involves carbs for glycogen re-stocking, protein for repairing and rebuilding muscle tissue, and fluids and electrolytes lost to sweat for rehydration. Try to consume 15-20g of protein within 30-60 minutes after exercise to increase muscle protein synthesis and optimize reloading of glycogen stores. This window of time is important, especially if you need to recover quickly, because your muscles are eager to refuel and can convert carbs into glycogen much faster than usual. Including protein also stimulates this process. If you are unable to refuel within this window, however, do not fret; recovery is an ongoing process and continues past the one-hour mark!

Tips for fueling after exercise:

  • Aim to eat a balanced meal or snack instead of more processed recovery products, if able. Some ideas: Turkey avocado sandwich; Veggie omelet with a small sweet potato; Greek yogurt with fruit and nuts; Toast with eggs and avocado; bagel with peanut butter.

  • It’s common to have a reduced appetite immediately after a hard or long workout. If you’re not hungry, have a light snack or something drinkable, such as a smoothie with yogurt and fruit. Refuel with a more balanced meal as soon as able.

  • Try prepping your post-run meal or snack the night before or morning of your long run, if you are too tired or don’t have time to make it when you finish.

Good luck and happy training! For individualized sports nutrition advice, please email me at to schedule a virtual or in-person nutrition consultation.

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