Marathon nutrition comes down to one central rule: fuel the training, not just the race. Your everyday diet during a 16–20 week build matters as much as what you eat the morning of the start. Get the daily fuelling right, roughly 55–65% carbohydrates, 15–20% protein, 20–25% fat, and race-day execution becomes far simpler. Get it wrong consistently across training, and no gel strategy on race day will compensate.

Use our Calories Burned calculator to estimate your training energy expenditure by session. That number is the foundation of how much you need to eat on heavy training days.

“Nutrition is the fourth discipline of running a marathon, after training, gear, and mental preparation.” — Nancy Clark, Registered Dietitian and author of Nancy Clark’s Sports Nutrition Guidebook

Why Marathon Nutrition Matters

The wall, the sudden, severe fatigue that hits many runners between kilometres 30 and 35, is a fuelling problem as much as a fitness problem. It occurs when muscle glycogen drops to near-zero, and the body can no longer sustain marathon pace. Research consistently shows that up to 32% of marathon runners hit the wall, and the majority of those cases are preventable with correct fuelling before and during the race.

Beyond avoiding the wall, consistent marathon nutrition supports muscle repair between sessions, maintains immune function across high-mileage training weeks, and keeps energy levels stable enough to actually execute quality workouts. Runners who undereat during training don’t just feel worse; they adapt more slowly.

Learn more about one specific component in our guide to hydration and its effect on running performance.

How Much to Eat During Marathon Training

Calorie needs during marathon training are meaningfully higher than a sedentary baseline, and they shift as your mileage builds. A useful starting framework:

Training frequency	Women (approximate)	Men (approximate)
3–4 sessions/week	2,500–3,000 kcal/day	3,000–3,500 kcal/day
5–6 sessions/week	3,000–3,500 kcal/day	3,500–4,000+ kcal/day

These are general estimates. Actual needs depend on your body weight, the intensity of your sessions, and your non-running activity level. On days with a long run of 25+ kilometres, expect to eat toward the top of your range or slightly above.

The most common beginner mistake isn’t overeating it’s significantly undereating during high-mileage weeks out of habit or weight concern. Consistent underfuelling during training leads to poor recovery, elevated injury risk, and flat workouts. If you’re following a structured marathon training plan, your nutrition needs to match the load the plan is placing on your body.

Use our Calories Burned calculator alongside your training log to track energy output across the week.

Macronutrient Breakdown for Marathon Training

Carbohydrates (55–65% of calories)

Carbohydrates are the primary fuel for marathon-pace running. Muscle glycogen the stored form of carbohydrate in the muscles, is the main energy source for anything faster than a very easy jog. You cannot outrun a chronically low-carbohydrate diet at marathon effort.

Focus on: oats, whole grain bread, pasta, rice, sweet potatoes, fruit, and starchy vegetables.

For a deeper dive on which carbohydrate sources work best for endurance training, see our guide to the best carbohydrates for runners.

Meal Timing: When to Eat Around Training

2–3 Hours Before a Run

Eat a carbohydrate-centred meal with moderate protein and minimal fat and fibre. The goal is adequate glycogen top-up without digestive discomfort.

Good options:

• Oatmeal with banana and honey
• Pasta with a light tomato sauce
• White rice with a small portion of lean protein
• Whole grain toast with peanut butter

30–45 Minutes Before (If Needed)

If you can’t eat a full meal 2–3 hours out, a small easily-digested carbohydrate snack close to the run works as a short-term supplement:

• Banana
• Medjool dates (2–3)
• A small oatmeal bar

Avoid before any run: Meat, fatty food, fried food, spicy food, high-fibre vegetables, legumes, and dairy if you’re sensitive to it. These slow down digestion and increase the risk of GI distress while running.

How Often to Eat

Most endurance athletes function well with three solid meals and one or two snacks built around training sessions. The key is not letting more than 4–5 hours pass without eating during heavy training periods, and ensuring a carbohydrate-protein snack or meal within 30–60 minutes after hard sessions or long runs.

Marathon Nutrition Plan: Step by Step

1. Everyday Nutrition During Training

The goal during training weeks is consistent, varied, nutrient-dense eating. No single meal matters as much as the overall pattern across the week.

Sample daily structure:

• Breakfast: Oatmeal with banana, almond butter, and a glass of milk or fortified plant milk
• Lunch: Quinoa or brown rice bowl with grilled chicken, roasted vegetables, and olive oil
• Snack: Greek yogurt with fruit and a small handful of nuts
• Dinner: Salmon or lean meat with sweet potato and steamed greens
• Post-run snack (if needed): Smoothie with banana, protein powder, and milk

Drink 2–3 litres of water daily, and more on long run days or in hot conditions. After runs exceeding 90 minutes, include electrolytes sodium, potassium, and magnesium rather than plain water alone. Our guide to electrolyte drinks for runners covers the options.

2. The Week Before the Marathon (Carbohydrate Loading)

The purpose of race week nutrition is to maximise glycogen stores before the start — not to experiment with new foods.

Current approach (2–3 day carbohydrate loading): The most practical and evidence-supported protocol for recreational runners is to increase carbohydrate intake significantly in the final 2–3 days before the race, while reducing training volume (tapering). This alone can increase muscle glycogen stores by 20–40% above normal training levels.

A study in the Journal of the International Society of Sports Nutrition found that carbohydrate loading improved endurance performance by up to 20%.

What to emphasise:

• Pasta, white rice, bread, bagels, and cereals
• Bananas, fruit juice, sports drinks
• Oatmeal and simple grain-based foods

What to reduce or avoid:

• High-fibre vegetables and legumes (gas, bloating risk)
• Large portions of fatty meat
• Alcohol
• Any food you haven’t eaten before

A note on sodium: Slightly increasing salt in meals during carb-loading week helps your body retain the extra fluid that comes with glycogen storage (each gram of glycogen is stored with approximately 3g of water). This is normal the slight weight gain from carb-loading is not fat, it’s fuel.

The older depletion-then-loading protocol (removing carbs for 3 days, then loading for 3 days) can produce higher glycogen stores in theory, but it causes significant fatigue, poor training quality, and GI disruption in many runners. Unless you’re working with a sports dietitian and have tested this protocol before, the straightforward 2–3 day loading approach is the better choice for a first marathon.

3. The Night Before the Race

Dinner the evening before the marathon should be familiar, carbohydrate-rich, and moderate in size. This is not the time for a large celebratory meal.

The goal: Top up glycogen, sleep well, wake up without digestive problems.

• Eat dinner at least 3 hours before your intended bedtime
• Keep portions moderate overeating causes poor sleep and morning discomfort
• Choose foods you’ve eaten before race-day starts in training
• Eat protein alongside carbohydrates (muscle maintenance overnight), but keep portions of protein and fat modest

Dinner example: Pasta or white rice with a small portion of lean fish (white varieties like cod or sea bass) or chicken breast. A small side of non-fibrous cooked vegetables if you tolerate them well. A bread roll. No salad, no heavy sauces, no new foods.

If you’re staying in a hotel or eating out: stick to simple pasta or rice dishes. Avoid raw vegetables, rich dressings, and anything you wouldn’t normally eat before a long training run.

4. Race Morning

Glycogen stores drop overnight as your body fuels normal metabolic functions during sleep. Race morning breakfast partially restores this it doesn’t replace carb-loading, but it meaningfully tops up liver glycogen and blood glucose before the gun.

Timing: Eat breakfast 2–3 hours before the race starts. If your start time makes this difficult (e.g., a 7 am wave), wake earlier rather than skipping breakfast.

What to eat:

• Oatmeal with banana and honey
• White toast or a bagel with peanut butter and jam
• White rice with scrambled eggs
• A sports drink alongside if appetite is low

Portion: Moderate. You’re not trying to eat a full day’s worth of carbohydrates — you’re topping up, not overloading.

What to avoid: High-fibre food, unfamiliar food, high-fat food, large amounts of protein, excessive caffeine if you’re not habituated to it. If coffee is part of your normal morning routine, keep it. If it isn’t, race day is not the day to start.

Our guide to what to eat before a long run has additional details on pre-race meal options and timing.

5. Race Day Fuelling (During the Marathon)

This is where most beginners make their most costly nutrition error: eating too little, too late.

The fundamental principle: Start fuelling early, before you feel like you need it, and keep fuelling consistently. By the time you feel glycogen depletion, it’s already affecting your pace.

Carbohydrate Intake During the Race

You’ll burn between 2,500 and 3,500 calories over the course of a marathon. Your body can absorb and utilise exogenous carbohydrates at a rate of 60–90g per hour for runs exceeding 2.5 hours provided you use a combination of glucose-based and fructose-based carbohydrate sources (which use different intestinal transporters). Most modern energy gels, chews, and sports drinks are formulated to provide this combination.

Practical targets:

• Start taking in carbohydrates at 30–45 minutes into the race, not when you feel tired
• Aim for one gel (typically 20–25g carbohydrate) every 30–45 minutes
• Supplement with a sports drink at aid stations for additional carbohydrates and electrolytes
• Total target: 60–90g of carbohydrate per hour for the latter stages of the race

A review in Sports Medicine found that endurance athletes who consumed carbohydrates during races improved performance by up to 11%.

Hydration During the Race

Sip water or a sports drink at every aid station rather than drinking large amounts infrequently. Drinking too much water without sodium can cause hyponatraemia (low blood sodium) a genuine risk in longer runs. Sports drinks at several aid stations across the race help maintain sodium levels.

Our guide to avoiding stomach issues during runs covers the GI side of race-day nutrition in detail.

6. Recovery Nutrition

The 30–60 minutes after finishing are as important nutritionally as the 30–60 minutes before the race start.

After a marathon, blood flow redistributes slowly from muscles back to the digestive system. Don’t attempt a large meal immediately after finishing; your stomach won’t thank you. Give yourself 20–30 minutes to cool down, change clothes, and let circulation normalise before eating.

Immediate (0–60 minutes post-finish):

• Something light and easily digested: a banana, a sports drink, or chocolate milk
• Target a 3:1 or 4:1 carbohydrate-to-protein ratio to begin glycogen replenishment and muscle repair
• Chocolate milk is genuinely one of the most practical post-race recovery foods: it provides fast-absorbing carbohydrates, whey protein, fluid, and sodium in one drink

Good options:

• Chocolate milk
• A smoothie with banana, Greek yogurt, and fruit juice
• A small rice bowl with chicken and a sports drink

2–4 hours post-race: A proper sit-down meal. Lean protein with carbohydrates and vegetables. This is when appetite typically returns properly, and it’s when the meaningful muscle repair nutrition window opens fully.

24–48 hours after: Continue eating well rather than treating post-race days as a free-for-all. Colourful vegetables, lean protein, whole grains, and consistent hydration accelerate the recovery process. Sleep quality in the first few nights after the race is probably the most important single recovery variable.

How to Avoid Stomach Issues While Running

GI distress is one of the most common reasons first-time marathoners have a difficult race. During intense exercise, blood flow diverts away from the digestive system to working muscles which is why food that sits fine in daily life can cause problems at marathon pace.

The practical checklist:

• Test everything in training. Gels, drinks, caffeinated products, electrolyte tabs, all of it at long-run intensity, not easy pace.
• Eat breakfast at least 2 hours before the start. Closer to 3 hours if you know you have a sensitive stomach.
• No new foods on race day. If you haven’t eaten it before a 20-kilometre training run, don’t eat it before the marathon.
• Avoid high-risk foods the day before and on race morning: legumes, raw vegetables, cruciferous vegetables (broccoli, cauliflower), high-fibre bread, spicy food, and large amounts of dairy.
• Be careful with caffeine. It can improve performance, but it also stimulates GI motility. If you’re not a regular coffee drinker, race day is not the time to start.
• Avoid carbonated drinks in the hour before and during the race, as they cause bloating during exertion.

Final Thoughts

To summarize, here are the basic nutritional recommendations if you are preparing to run a marathon.

Everyone who is actively training needs to watch their nutrition. Marathon runners have a higher caloric intake due to the high energy expenditure during training, but that doesn’t mean you can eat whatever you want. We eat to run, not the other way around.

The basis of your marathon training diet is complex carbohydrates (60-70%), about 20% protein, and 10% “healthy” fats. Daily calorie intake can be about 3000 kcal for actively training women and 4000 kcal and even more for men.

The number of meals, according to modern research, should not be large, so as not to create conditions for the development of insulin resistance.

Exclude from your diet sweets, flour, fried heavy food, sauces, convenience foods, and fast food. These are “empty” calories that do not carry any benefit to the body.

Eat a varied diet – this will ensure the intake of all necessary substances. If you can’t eat a full diet or if you follow a certain dietary pattern (vegetarianism, for example), compensate for deficiencies with supplements.“Fueling well is a learned skill. The more you practice it, the better you’ll perform.”
— Tina Muir, elite runner & host of the Running for Real Podcast

Frequently Asked Questions