Preparing for a marathon involves rigorous training, but equally important is fine-tuning your nutrition strategy. Proper nutrition can significantly impact your performance and recovery.

Here are some common mistakes marathon runners make with their nutrition, and tips on how to avoid them at various stages of your marathon journey.

Weeks and Months Before the Race

1. Not Incorporating Intra-Race Nutrition into Training 🍊

Your body needs time to adapt to the foods you’ll consume during the race to avoid digestive issues. Aim to consume about 60-90g of carbohydrates per hour and start incorporating this into some of your training sessions 6-12 weeks out. Some athletes may consume up to 120g of carbohydrates per hour.


2. Not Monitoring Fluid Intake and Sweat Rate During Training 🥵

Excessive dehydration (loss of >2-3% of body mass in hot conditions and >3-4% in cooler conditions) can impair performance. Since there are limited aid stations on race day, it’s crucial to monitor your sweat rate and fluid intake during training.

3. Eating in a Calorie Deficit 🪫

While fat loss is certainly possible during this time, it is not optimal. With high training volumes, eating in a calorie deficit increases the risk of muscle or bone injuries. Instead, cycle your energy intake throughout the year to achieve race weight while ensuring adequate energy availability during non-competition periods. Avoid dietary deficiencies, particularly low protein or carbohydrate intake, and ensure you get enough vitamin C, D, copper, omega-3 fatty acids, and calcium.

Days Before the Race

1. Not Carb Loading Sufficiently 🍝

If you are running a marathon, then carb loading would be strongly recommended. Carb loading results in high muscle glycogen concentrations (which is the storage form of carbohydrate). Carbs are the petrol and glycogen is the tank in your car. Eating about 5-12g of Carbs/kg of bodyweight per day would be recommended and aim for at least 8g/kg if you are running a marathon. Doing this 2-3 days out from your race will suffice.

2. Excessive Fibre Intake 🫛🫘

For an athlete in training, a diet with adequate fibre will help keep the bowel regular. However, on race day we want to see a reduction in bowel movements. Stick with simple carbs such as white rice, white pasta, white bread in the days before your race and avoid any high-fibre veg. Veg such as zucchini, tomatoes and olives are low in fibre.

3. Ignoring Hydration Practices 💧

Runners often focus on hydration on race day and ignore it in the days before. With an increase in carbohydrates in the days before the race, sufficient water intake is paramount. For every 1g of carb consumed, ~3 grams of water are retained (predominantly in the muscles). Multiply 40mls x your bodyweight (in kg) to get a rough starting point of how much water you should be drinking.

Morning of the Race

1. Drinking Too Much Water 🌊

Too much water can lead to stomach issues or potentially hyponatremia (low levels of sodium in the blood), which can be fatal. Aim to drink ~500 to 600 ml of water or sports drink 2 to 3 hours before exercise and an additional 200 to 300 ml of water or a sports drink 10 to 20 minutes before exercise. This can vary depending on the individual.

2. Carb-Loading on the Morning of the Race 🍚🥯🍝

This can lead to digestive issues and hamper your race day performance. Instead, aim for ~2-3g of carbs/kg of bodyweight ~2-3 hours before the race. Keep fat, fibre, and dairy intake low in this meal. If you only have 1 hour to eat prior to the race and have a history of digestive issues when running, aim for only 1g of carbs/kg of bodyweight.

3. Trying Something New to Eat on the Morning of the Race 🥪

Your body needs time to adapt to new foods, so don’t try out a new breakfast option on race day. Your pre-race meal should be tried and tested at least 6 weeks out to reduce any risk of GI issues during the race.

During the Race

1. Trying Out a New Source of Carb 🤮

It can be tempting to try out a new energy gel or liquid that you haven’t tried before, but don’t do this during your race. Your body needs time to adapt to new foods. Trying out a new carb source during your race risks digestive issues, which could cost you time or even result in a DNF (Did Not Finish).

2. Drinking Too Much 🌊

You don’t want to be stopping to use the toilet every 30 minutes – you’re losing precious time. Too much water can lead to stomach issues or hyponatremia. Aim for somewhere between 400 and 800mls/hour, although this can be higher depending on the individual and the environment. Break this up across the hour, for example, every 15-20 minutes, aim for 100-300mls to reduce the chance of digestive issues.

3. Skipping Fuelling Stations

Skipping stations can result in insufficient intake of carbs or water, harming your performance. Also, trying to compensate later can cause gastrointestinal distress. Regular, moderate intake is easier on the digestive system.


After the Race

1. Delaying Nutrient Intake ⏱️🍌

Many runners wait too long to eat after finishing the marathon. This delay can hinder the body’s ability to replenish glycogen stores and repair muscle tissue, leading to prolonged recovery times and increased muscle soreness. Aim to consume at least 1g of carbs/kg of bodyweight within the first hour after the marathon along with 25g of protein. For example, a 750ml carton of Mooju would suffice for a 75kg runner. Within 4 hours after training, aim to have a further 3g of carbs/kg of bodyweight.

2. Insufficient Rehydration 💧

Some runners fail to rehydrate properly after the race, either drinking too little or consuming the wrong types of fluids (like a creamy pint of Guinness). This can lead to dehydration, electrolyte imbalance, and delayed muscle recovery. Rehydrate with fluids that contain electrolytes, such as sports drinks, coconut water, or water combined with electrolyte tablets. Aim to drink small amounts frequently rather than a large quantity all at once. Monitor your urine color; it should be pale yellow. A more accurate method is to consume ~1-1.5L of fluids for every kg lost as sweat.

By avoiding these common mistakes and following these nutrition tips, you can enhance your marathon performance and ensure a smoother recovery. Happy running!