Can You Run A Marathon Without Eating?

Serious athletes spend years planning, exercising, and preparing to run marathons. Running 26.2 miles puts tremendous strain on the body. Therefore, eating and hydrating sufficiently play a significant role before, during, and after such a grueling event.

Can you run a marathon without eating?

It is possible to run a marathon by only hydrating and not eating, but it is not advisable. 

Marathon runners need enough carbohydrates and liquids to guard their bodies against glycogen depletion. Glycogen is the prime fuel source for distance runners and needs replenishment throughout a marathon.

Human bodies need fuel from food and hydration to perform optimally, especially when athletes run marathons challenging their energy reserves. Anybody who is experimenting with intermittent fasting should serious reconsider doing so on the race day of a marathon!

While you could feasibly run a marathon on no food, you’re probably going to regret your decision and enter a whole new world of pain if you try.

Let’s find out why:

Why You Need To Eat During A Marathon

Can you run a marathon without eating?

Average runners store adequate glycogen in their muscles to reach the halfway mark. After this, it is crucial to replenish the glycogen levels to ensure enough energy is available to finish the marathon.

This is why we can run a half marathon without fuelling, but will bonk out if we adopt the same strategy for a full marathon.

A runner’s body burns fat and sugars to provide the necessary energy needed to fuel the body.

Carbohydrates release energy much faster than fats or protein, making carbohydrates the first choice when replenishing depleted energy sources.

The key to the successful completion of a marathon is a balance of carbohydrates, fluid, and electrolytes. Nutritional and fluid balance is of utmost importance when heading into your run. If not balanced, you may run out of energy and not complete the race or risk losing vital resources too quickly, putting unnecessary strain on the body.

Food provides the necessary elements to keep the body properly fueled, enabling the runner to finish the race and score a good time.

Fuelling well is almost as important as training well, and you’d certainly be brave to attempt a marathon with no prior training.

What Do Athletes Eat During A Marathon?

The most significant fear distance runners face is that they will run out of glycogen, the fuel needed to finish marathons. “Hitting the wall” or bonking is something every runner needs to avoid at all times.

When glycogen levels deplete, the brain and body show signs of fatigue, causing the runner to slow down or stop entirely. To prevent bonking, runners need to replenish their fuel supply by eating and hydrating, keeping the fluid, electrolyte, and carbohydrate balanced.

It is essential to maximize your energy stores before and during the race.

“Carb loading” prevents bonking and means adding loads of carbohydrate food to your diet.

Carbohydrate-rich foods include pasta, rice, potato, and fruits such as bananas, mangoes, and figs.

Vegetables rich in carbohydrates include sweet potatoes, corn, and beets. Carbohydrates release energy far quicker than fat and proteins.

If consuming solid foods during a run makes you feel bloated and uncomfortable, you can substitute them using energy gels and chews. But remember, always try them during practice to see how the body reacts to them. 

What And When To Eat During A Marathon

The best food to consume during a race is high in carbohydrates, and carbohydrates release energy quickly.

Eating every forty-five to sixty minutes during a long run is essential. Eating a large banana, using gels, or having a white bread and honey sandwich will provide much-needed energy.

Runners must stay hydrated by drinking fluids and electrolytes.

The Ten Best Foods For Marathon Runners

Runners know the importance of a healthy diet and plan their meals accordingly. What you eat while preparing and training for a race plays a significant role on race day.

The best foods for marathon runners include:

  • Whole grain pasta is a high-carb meal that replenishes glycogen levels that provides energy during the race.
  • Potatoes are rich in potassium, vitamins, and antioxidants that protect the body from diseases and help the body to function correctly.
  • Broccoli is full of vitamin C preventing sore muscles after strenuous exercise. In addition, vitamin K, calcium, and folic acid in broccoli assist in strengthening bones.
  • Bananas contain potassium that compensates for the loss of minerals due to sweating. In addition, bananas are high in carbohydrates that provide energy.
  • Oats are a low GI, high carbohydrate food. Providing energy over a more extended period.
  • Plain Yogurt speeds up recovery time and protects the muscles. Calcium aids in strengthening the bones.
  • Consuming dark chocolate in moderation lowers cholesterol, blood pressure, and inflammation.
  • Beets are high in antioxidants, support the immune system, and prevent sore muscles.
  • Coffee taken without sugar and milk boosts high-intensity workouts and helps you to run faster and finish quicker.
  • Peanut butter without the added salt, oils, and sugar contains vitamin E, a powerful antioxidant. In addition, healthy fats lower cholesterol levels. Peanut butter strengthens the immune system, supports muscle growth, and speeds up post-run recovery.

Four Foods Runners Should Avoid

Runners need to take care of what they eat – but that is particularly the case on the morning of a marathon (or an ultra!)

Here are five foods runners should avoid:

  • Sugary drinks quench thirst quickly but have pitfalls. Sugary drinks cause sugar cravings and lead to dehydration.
  • Frozen foods contain extreme amounts of fats, sodium, and calories. Therefore, runners should avoid consuming frozen foods.
  • Dairy products may cause digestive problems often due to lactose intolerance.
  • Alcohol such as beer is a diuretic that leads to dehydration, causing cramps and fatigue.

Three Important Food Tips For Race Day

Beginner runners should make mental notes of the following tips to prevent race day pitfalls.

  • Do not divert from the nutritional plan you decided on and used during preparation for the marathon. Instead, adjust slightly according to your needs on the day.
  • Do not try any new products on race day. 
  • Adjust your fluid consumption according to your body’s needs on the day.

What To Do If You Struggle To Eat Solids During A Marathon?

What works during practice and preparing for running a marathon often tends to not work on race day no matter how well you condition yourself.

Consuming solid food is a challenge for some runners, who may only realize this during the race. These runners then need replenishment through fluids instead of solid food. These fluids include gels and drinks with slow energy releasing properties.

When struggling to consume overly sweet gels and liquids, consider taking the diabetic versions that are not so sweet.

Author Profile

Alex Randall

Photo of author
Alex is the editor at Revel Sports. It was his idea to take our post-club-run chats and build a website out of them. He is responsible for dotting the I’s and crossing the T’s when any of us have something to post. (Basically: it’s all his fault). A ferocious 5K powerhouse on his day, Alex is known for not understanding the meaning of the term ‘negative split‘.
Alex Randall

Revel SPorts Contributor

Leave a Comment