What Foods Make a Runner Slower?

When less than one second can change whether an athlete finds themselves on the podium or not, all aspects of what contributes to a slower run should be fine-tuned. Nutrition and food are one area to be highlighted as they can greatly affect the speed of an individual. So, what foods make a runner slower?

Foods that can slow down a run include high fat foods, sugary foods, artificial and non-nutritive sweeteners, high fiber foods, and milk (for those sensitive to lactose). Not eating enough food can also make a runner slower.

There’s more than a short list of foods to avoid. Foods which slow down a run can change depending on the individual, time, and circumstance. For instance, a large pasta meal the night before an event can provide the energy needed for a great run. Yet, when teens eat this same meal less than an hour before the event, they may find themselves slowing down with a stomachache or other gut discomfort.

Continue to read for more information from a registered dietitian nutritionist about how foods eaten can affect the speed of a run and what to do to get faster.

Foods to Avoid Immediately Before a Run

Teenage athletes are at such a crucial time to balance nutrition for growth and athletics. The correct nutrients at the correct timing is important for a run, whether you are an endurance runner or sprinter.

In the 1 to 2 hours before an event, teen runners will want to carefully choose what they eat. The foods eaten during this time can significantly impact their running.

Choose a fueling snack 1-2 hours before a run. What teen runners choose to eat can either help fuel a burst of speed or weigh them down for a slower run time

Here’s a List of Foods That Will Slow Down a Runner:

  1. High Fat Foods

High fat foods include fried foods, many desserts, nuts, nut butters, cheese, burgers, pizza, and chips. Fat takes longer to digest, which can cause stomach pain while running. These foods can still be enjoyed by an athlete in moderation further out from the event. 

  1. Sugary Foods

Foods high in sugar include candy, ice cream, desserts, and sweetened cereals. Some sneakier high sugar foods include muffins, granola, yogurt and even granola bars. Foods high in sugar can cause blood sugar to spike and then crash, leaving an athlete feeling fatigued and slow.

 In general these foods should be eaten only in moderation. However, athletes will find that including these high sugar foods along with a balanced diet in the weeks prior to a race will not ruin their running times. Teenagers should avoid complete restriction of any food as restriction can increase the likelihood of disordered eating patterns. Healthy eating patterns can include some sugary foods in the right balance and moderation, at the proper timing for teenage runners.

  1. Artificial Sugars, Sugar Alcohols, and Non-Nutritive Sweeteners

Artificial sugars and sugar alcohols are often found in diet and sugar-free products. These include aspartame, saccharin, xylitol, etc. and can cause bloating and diarrhea when consumed in large quantities. Artificial sugars are what gave sugar free gummy bears their infamous reviews about uncomfortable digestive problems.

On other days, an athlete may still want to limit these foods with non-nutritive sweeteners. A teen athlete has high energy needs, which may not be met through these foods. Focus on eating whole foods.

  1. High Fiber Foods

High fiber foods include beans, whole grains and some fruits and vegetables. While high fiber foods are generally encouraged as part of a healthy diet, they can cause stomach discomfort to runners when eaten too close to an event. In general a teen athlete will want to include these high fiber foods in their diet, just not too close to running.

Personal tolerance is important. It can be wise for most teen runners to limit high fiber fruits, vegetables, whole grains, and beans within 1-4 hours before running.

  1. Milk (for Those Sensitive to Lactose)

Milk and milk products contain lactose, which some individuals may find difficult to absorb. Athletes with lactose sensitivity may experience diarrhea, bloating, stomach pain and even vomiting. However, athletes without this lactose sensitivity may not need to avoid milk products. Know your personal tolerance. Don’t consume dairy products before running if it may cause digestional problems.

  1. Not Enough Food

Calories are the energy athletes use to run. Just like a car cannot run without fuel, neither can an athlete. Care should be taken to eat adequate calories to meet the energy demands of the sport and healthy growth.

Check out my post: How Many Calories Should a Teen Runner Eat?

What Should an Runner Eat Before Running?

A meal eaten before a run should involve a good balance of carbohydrate, protein and fat.

Carbohydrates– grains, fruit, vegetables, legumes, dairy

Protein– meat, poultry, fish, eggs, dairy, legumes, nuts and nut butter, seeds, oatmeal, edamame

Fat– nuts, seeds, oils, avocados, fatty fish, dairy products

What to Eat 3-4 Hours Before Running

A meal eaten 1-2 hours prior to an event may look similar to a meal eaten 3-4 hours prior to an event, but on a smaller scale. The athlete may also want to decrease the fat and fiber in the meal. For example, a small breakfast burrito with a whole wheat tortilla, eggs and a piece of fruit.

For example, a great pre-run meal would be a breakfast burrito with a whole wheat tortilla including eggs, beans, vegetables and cheese with a piece of fruit. Because this meal has several hours to digest, the fiber and fat should not affect the running speed, but will help prevent a blood sugar crash and provide long lasting energy. 

Best Examples For Fueling Pre-Run Meals:

  • Pasta with chicken and veggies
  • PB&J sandwich
  • Greek yogurt parfait
  • Waffle with nut butter and fruit
  • Rice cakes with hummus (depending on personal tolerance)
  • Bagel sandwich
  • Cottage cheese and fruit slices
  • Cold cereal and milk
  • Tuna pouch with pita crackers
  • Rice with curry and veggies
  • Veggie pita pocket

Best Examples For Fueling Pre-Run Snacks:

If you get hungry again within 1-2 hours before a race, choose a small fueling snack of carbohydrates for additional energy. A meal eaten 1-2 hours prior to an even should be less of a meal and more of a snack. This snack may look like an egg on toast or a banana with a small amount of peanut butter. Most athletes do well to avoid eating less than thirty minutes before running to avoid an upset stomach.

  • Fruit smoothie
  • Energy bar and fruit
  • Trail mix and dried fruit
  • Toast with nut butter and a banana
  • String cheese and crackers
  • Hard boiled egg and juice
  • Pretzels and peanut butter
  • Fruit leather
  • Dates

See also:

What to Eat When Preparing for Race Day

Each athlete will find an individual eating pattern that works best for them. Athletes should avoid introducing new foods or changing up their eating pattern in the days leading up to an event and stick to familiar meals and snacks. 

During this time and in the weeks prior to a race, athletes should stay well hydrated. Dehydration will dramatically impact the speed at which an athlete can run. While the amount of liquid needed to stay hydrated varies from person to person, the color of urine can indicate hydration status. A pale yellow urine color shows adequate hydration.

Will Supplements Help Runners?

Supplements are popular among the teenage crowd. Protein powders, creatine, BCAAs, caffeine, and more.

The lack of certain nutrients can negatively impact speed. On the other hand, eating too much of certain nutrients does little to boost speed and can even harm the body. The use of supplements to meet vitamin and mineral needs should only be used if an athlete’s diet cannot provide what he or she needs. If supplementation of certain vitamins and minerals are necessary, one should seek the guidance of a doctor or registered dietitian. 

Supplements are not well regulated and multiple studies show that they often contain less or more of substances claimed on the label and even harmful contaminants for teenage runners. If athletes decide to use supplements, they should look for third party testing labels such as NSF, USP, UL or Consumer Labs. For most athletes, the best way to ensure appropriate consumption of these nutrients comes from eating a balanced and varied diet.

See also:

Important Nutrients for Teenage Runners


Iron helps carry oxygen throughout the body and when teen runners do not have enough iron it’s a lot harder to get enough oxygen to all their muscles and they will tire easily. Girls are more likely to experience a deficiency in iron though loss of blood by menstruation and also through dieting. 

Most meats contain high amounts of iron. Outside of meat, iron can be found in beans, fortified grains such as cereal, and some leafy greens. The body does not absorb the iron in these non-meat sources as easily. However, absorption will increase when plant-based iron sources are combined with foods high in vitamin C such as tomatoes, citrus fruits or peppers. Iron supplements should only be taken under the guidance of a doctor or registered dietitian. 


Calcium helps with bone strength and muscle contraction. A lack of calcium can increase the risk for poor bone health and stress fractures. The teenage years are crucial to developing long lasting bone health as the ability to build bone dramatically decreases after the early twenties.

Calcium rich foods include dairy products, canned fish with bones, fortified orange juice, almonds and some dark green vegetables.

Vitamin D

Vitamin D also helps build strong bone and a lack of this vitamin is associated with fatigue and getting sick easier. 

Most Vitamin D comes from the sun, but is also found in foods fortified with vitamin D such as milk, eggs and mushrooms grown under UV lights. 

Even with a healthy, well-balanced diet, many teenage athletes may benefit from a vitamin D supplement. Check with a doctor for blood tests to check levels.

B Vitamins

B vitamins (Thiamin, Niacin, Riboflavin B6, B12, Folate, Biotin, Pantothenic Acid) help with energy, blood cell production and muscle repair. While studies show no benefit from excess B Vitamins, too little of any of these vitamins will affect performance. 

Many different foods contain B vitamins including most grains, meat, nuts and green vegetables. Vegetarian or vegan athletes may want to talk to their doctor about B-12 supplementation. 

What About Caffeine for Teen Runners?

Research with adults show improved athletic ability after taking caffeine. However, caution is advised with youth as not enough studies have been completed to establish whether the benefits of taking caffeine outweigh the risks. In fact, most organizations discourage the use of caffeine as a supplement for those younger than eighteen. Youth digest caffeine differently than adults, which increases the likelihood of toxicity and other ill effects.

Excess caffeine can lead to side effects such as insomnia, anxiety, dehydration, headaches, shakiness and a rapid heartbeat. Children often get their caffeine through high sugar products such as energy drinks and soda, which can also negatively impact running speed. Furthermore, energy drinks may contain other harmful substances and carbonated drinks can cause uncomfortable bloating.

See also: Is it OK for Teenagers to Drink Tea? Ask a Dietitian

If you’re looking for more specific help for your season from a registered dietitian nutritionist, check out my ebook. Nutrition Game Plan for Teenage Athletes.

Includes month-long meal plan, weight tips, supplement tips, snack list, hydration tips, and more. Check it out here.

The Bottom Line

Runners need to properly fuel their energy needs. Nutrition is just as important as training so make a plan, prepare wisely for snacks and meals. You’ll see your stride lengthen, energy and endurance increase, and hit all new PRs.

Related Questions

Can Runners Eat Junk Food? Runners can eat junk food in moderation. Runners should not eat junk food before a run. Some runners benefit on long runs from eating quick sugar to spike their blood sugar for fast energy.

Are Bananas Good for Runners? Bananas have healthy carbs that provide energy for a run. Bananas also provide potassium to help muscles and provide electrolytes. Bananas are an easy fruit for on-the-go, making them a runner’s favorite.

Is Coffee Good for Runners? Caffeine may be helpful for adult runners, but benefits may not outweigh the risks of youth taking caffeine for a run. Coffee should be avoided before a run for teenagers.

Should Runners Eat a Lot? The energy needs of runners are among the highest energy needs of all athletes. Runners need to be properly fueled before, during, and after a race. Runners should eat about 3 meals a day of 600-800 calories and about 1-3 snacks per day of 100-300 calories each. Runners should eat healthy carbohydrates and protein, and plenty of healthy fats.

See Also

Katherine Harmer, RDN

I'm a Registered Dietitian Nutritionist with a love for coaching others to success in their health goals, especially teenage athletes. Tennis was my sport of choice in high school. Now I'm a little bit older, a little bit smarter, and a little bit worse at tennis.

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