A friend asked me if I could recommend a book on nutrition for her half marathon training. I started pouring through my bookshelf for a book to recommend and one thing became clear: most available material targets advanced-level marathoners, which can feel overwhelming but also proves unnecessary for the average runner.
Reading about calculating exact carbohydrate grams per hour per kilograms of body weight can feel like overkill, and it often intimidates runners into not creating a nutrition plan at all. Understanding nutrition should not be an obstacle to your training. My goal is to provide some straightforward information that you can immediately run with (pun intended).
For runners and walkers aiming for a half marathon finish within the 2.5 to 4-hour range, including those just trying to finish strong at any pace, nutrition is undoubtedly important, but it does not need to be intimidatingly precise. I can help you with general guidelines and invite you to approach your fueling as a personal experiment as you train, allowing you to figure out what works best for your body. No math required.
Taking the Pressure Off: Your Half-Marathon Fueling Experiment
I can help you build a nutrition plan that is a guide, not a rigid set of rules or a prescription. As a board-certified health coach, running coach, and personal trainer, not a registered dietitian, I want to emphasize that if you have unique health concerns, such as diabetes or chronic digestive problems, you should always consult your medical and nutrition team for specific support. For everyone else, embracing the mindset of an experiment can be freeing and effective. Luckily for you, the 12-16 week half marathon training cycle is the perfect time to test and learn. Think about it as training your nutrition along with training your body for the race.
The goal of your half marathon fueling is to ensure your body has the ready energy it needs to perform well and the nutrients required to repair and adapt afterward. Winging it risks leaving performance on the table, increasing injury risk, and leading to a less pleasant experience. The good news is that achieving good fueling doesn't require complex planning, just basic information and a willingness to experiment.
The Fueling Framework: Pre, During, and Post Run
Pre-Run Fueling: Runs Under 60 Minutes
For most of your regular training sessions lasting less than an hour, a large meal is certainly unnecessary, but a quick source of energy can make your run feel much better. While it is tempting to skip food if you are heading out early, trying to run while fasting can be counterproductive for some; even just a small amount of carbohydrate helps your body perform better.
You can experiment to see how you feel and perform after a small snack versus running completely fasted, and then make an informed choice. Generally speaking, consuming a little fuel will support better performance and energy levels. If you run early in the morning, opt for a small, easily digestible carbohydrate-based snack to give your body immediate energy. Try half a banana, a few sips of a sports drink, a small piece of toast, or a handful of crackers for this quick fuel, prioritizing whatever makes your stomach feel settled and supports a strong workout.
Pre-Run Fueling: Runs Over 60 Minutes and Long Runs
Once your runs extend beyond an hour, or are scheduled for your weekly "long run" (even if you plan to walk), having a proper pre-run meal becomes more important. Fueling helps you focus on topping off your accessible energy reserves so you feel steady and strong throughout the entire workout. The general guidelines for this pre-run meal are: mostly carbohydrates, moderate protein, and low in fiber and fat. This nutrient balance promotes quick digestion and helps prevent stomach upset, ensuring you feel comfortable and light as you begin to move your body.
Examples of Pre-Run Meals
You could try two slices of low-fiber toast, like white or sourdough, with a thin layer of jelly or honey, paired with two to three scrambled egg whites. Another great option is a full cup of instant oatmeal or quick oats, topped with a small handful of raisins and a spoonful of low-fat Greek yogurt or low-fat cottage cheese mixed in. Alternatively, you might try three or four rice cakes spread with a thin smear of jam, paired with two thin slices of lean deli turkey or chicken breast.
Do I need to Carb Load?
"Carb loading" is an advanced strategy and can be effective, but let's not overthink it when preparing for your half marathon. Instead, you can start experimenting by eating a carb-heavy meal the night before your longer run. Eat pasta, potatoes, or rice to help top off your fuel reserves. There is no need to go crazy; simply prioritizing normal or slightly larger-than-normal servings of healthy carbohydrates is enough, and then you can see how it makes you feel the next day on your run.
If you usually restrict carbohydrates or follow a low-carb diet, you will likely feel a significant difference in your energy levels and performance. If you normally eat carbohydrates, it may just result in a comforting feeling of steady energy. If you feel overstuffed or bloated, you may have taken the volume too far, and that is the beauty of experimenting to find the right balance. This isn't something you try out the night before your big race; it is what you start playing with before your very first training run that is over an hour, and the experimentation should continue throughout your entire training cycle. By race day you will know exactly what to eat to feel and perform your best.
Fueling During the Run: Strategy and Experimentation
For runs lasting 90 minutes or longer, your body needs calories during your run to maintain pace and avoid severe fatigue. During lower-intensity efforts, such as walking a half marathon or running at a very conversational pace, you will still deplete your stored energy, but perhaps not as quickly or drastically as someone running at a consistently higher intensity. You may not experience the traditional, sudden "hitting the wall" that comes with rapid energy depletion, but you will undoubtedly feel low energy, and your pace and enjoyment may suffer if you do not take in calories.
Your training period becomes the laboratory for your race day. Your goal is to train not just your muscles, but also your digestive system to handle fuel on the move. By starting this testing several months before your race, you will have a fine-tuned strategy based on your own unique experience.
Quick Sugar and Training Your Gut
Your body uses fast-digesting sugar during long-duration activity, and this is what you need in the middle of a long run.
Experimentation involves finding out the following:
What type of fuel does your stomach tolerate best? Try different brands, types, and consistencies on your longer runs. Experiment with popular gels like GU or Maurten, chews from brands like Clif Bloks or Skratch, or even simple snacks like waffles, dates, or sports drinks.
How much fuel do you need? For intra-run fueling during long practice sessions, a general starting suggestion is to consume around 100 calories every 45 to 60 minutes. Use your long runs to determine if you feel better by taking in more or less than the suggested amount.
The timing that prevents stomach upset or energy dips. Pay attention to whether you feel best when you fuel at the 45-minute mark or closer to the hour mark. Try different timing on different runs. The key is to take in calories before you feel the energy dip.
You may see marketing on sports fuel that highlights "low sugar," but this is playing into popular dieting trends. I do not advise using these products because the primary purpose of sugar during a run is to provide immediate energy to your working muscles and brain, preventing a sharp drop in blood sugar that can lead to fatigue. In this case, low sugar is not helpful for your immediate goals. What you might not deem healthy on a typical day, such as consuming a sugary gel or a handful of gummy candies, is entirely appropriate for a long run because the situation is completely different. It is the best choice for your body in this situation, providing the quick-burning fuel for sustained effort.
Post-Workout Recovery
Fueling for recovery is just as crucial as fueling for the run itself. Under-fueling causes future runs to feel harder, limits performance, and increases your potential for injury, as nutrition plays a huge role in recovery, alongside rest and adaptation.
Aim to consume a mix of carbohydrates and protein soon after your long run. A simple guideline is to choose a recovery snack that provides approximately four times as many grams of carbohydrates as it does protein. This combination of nutrients helps your body quickly replenish its immediate energy reserves and begin the critical process of repairing and rebuilding muscle tissue. The protein is vital for repairing the micro-tears in your muscles caused by running, which allows your body to adapt and get stronger.
Examples of Immediate Post-Run Snacks and Meals
For immediate post-run snacks, chocolate milk naturally hits that desired ratio and is easy to drink when you might not feel like eating. A smoothie made with fruit (banana, pineapple, whatever you like), a handful of spinach, and a scoop of protein powder or Greek yogurt is another excellent choice. Other options include a sandwich with turkey or chicken, or scrambled eggs with toast or a tortilla.
If a main meal follows your long run, you can easily meet your recovery needs with common dinner foods by adjusting the portions to favor carbohydrates. For example, in a meal of potatoes and chicken, prioritize a generous serving of mashed or baked potato over the volume of the lean grilled chicken breast. If you prefer pork and rice, ensure you have a large scoop of rice or rice pilaf paired with a serving of lean pork tenderloin. Or, for pasta with marinara sauce, the serving of pasta should be the main fuel source, paired with ground turkey or diced turkey breast mixed into the sauce. For a beef stir-fry, try serving it with plain rice to absorb the sauce and accompany it with thinly sliced lean beef. Consistency is key, so choose options you genuinely enjoy; your personal preference is what will keep you fueling effectively.
Calories: Your Literal Energy Source and Recovery Engine
Maybe it’s my role as a personal trainer, but a lot of women I meet are on some sort of diet or calorie restriction. For your half-marathon training, calories are not something to be feared; they are literally the energy your body needs to perform, recover, and exist. You need them to complete your training, feel good on race day, and maintain your overall health.
One of the most telling signs of under-fueling is an extreme drop in energy hours after your run, such as falling asleep in the middle of the day. Your body is simply attempting to conserve energy because it lacks the necessary resources to stay awake and move.
Under-fueling forces your body to break down muscle for energy, slow metabolic functions, and prevent the adaptations that make you a stronger runner. Bad fueling habits can lead to burnout, increased injury potential, and a bad race experience.
Endurance Training and Dieting: A Tricky Combination
I hate to be the bearer of bad news, as I often have to gently inform my training clients that endurance training and dieting are generally a bad combination. People often sign up for half marathons because they think it will help them lose weight. There is a mismatch in goals because dieting requires an energy deficit, while training needs those extra calories to perform and recover fully.
While you will burn a lot of calories during your long runs, you must refuel to recover and consume more calories during the run itself. Also, it is very common to move less after a long run, which lowers your overall caloric expenditure for the entire day. That run is not burning as many total calories as you think once you factor in the necessary fuel and the reduced movement afterward.
There is also the simple fact that the more you run, the more efficient your body gets. Adaptation is a good thing; it is the entire reason you can train to run 13.1 miles over 12-15 weeks. Your body adapts to the demand, which means it doesn't work as hard over time to cover the same distance. The good news is that running becomes easier; the less-welcome news (sometimes) is that it means you burn fewer calories for the same effort.
You will likely need to eat a lot to sustain yourself while training for a half marathon. While you are burning a lot of calories, focus on nutrition for optimal performance. Choosing a fat loss phase after your race is often the best strategy for sustainable results and a much more positive training and racing experience.
The Missing Link: Connecting Food to Performance
One common mistake runners make is failing to connect the dots between what they eat and how they feel. They might cut calories too low, have a tough run, and never associate the two. Or they might eat a large, greasy meal the night before a long run and then be surprised by stomach or bathroom issues the next morning. It is also common for a runner to try a gel once during a long run, experience stomach issues, and then decide that no intra-workout fuel will work for them at all.
It is important to not only to track what you eat but also to reflect honestly on how it made you feel during and after your run. Take note of your natural hunger and fullness signals. Notice how a large portion of simple carbohydrates the night before gave you more accessible energy, or how alcohol slowed your recovery. Pay attention to what foods made you feel good, and which one’s didn’t Your body provides clear feedback; your job as the runner is to pay attention and adjust. This reflection will inform your race day strategy.
Your nutrition plan should ultimately be a plan that works for you, built upon the knowledge gained through weeks of focused training. When you treat your fueling as an ongoing, personal experiment, you take ownership of your success. By testing and tuning your dials, from your pre-run snack to your intra-race gel, you eliminate unnecessary surprises. Embrace this process, trust the data from your own body, and step up to that start line knowing you have a reliable, fine-tuned plan to carry you confidently to the finish.
As you are training for your fall and winter race schedules, I’d love to hear how you are planning your nutrition strategy for the best outcome.
Questions? I’d love to help.
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Lea
Lea Genders is a board-certified health coach, personal trainer, and workplace wellness consultant based in Fort Worth, TX. She offers corporate wellness programs for employee health and productivity, as well as in-person and virtual training / coaching for individuals worldwide. Her blog shares expert guidance on strength training, running, and sustainable nutrition @fortworth_trainer
A lot of nutrition guides for half marathon training are overly complicated and aimed at elite athletes, which can be intimidating for the average runner. This blog post is about taking the pressure off by treating your fueling as a personal, no-math-required experiment throughout your 12-to-16-week training cycle. As a health coach and personal trainer, my goal is to give you simple, straightforward guidelines so you can figure out what works best for your body, ensuring you have the energy needed to train well, recover fully, and cross the finish line feeling strong.