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Top Foods Runners Should Avoid: Worst foods to eat

Posted by George Parker on

Top Foods Runners Should Avoid

By George Parker, Georgia Tech Chemist & Engineer, 7x Boston Marathon Qualifying Runner, and Founder of Peregrune®, which engineers vitamins and supplements exclusively for runners.


For runners, nutrition is just as crucial as the miles logged. What you eat can significantly impact your performance, recovery, and overall health. While there are many foods that can fuel your running endeavors, some can hinder your progress and should be avoided. Here are the top foods that runners should steer clear of, supported by medical, clinical, and academic sources.

1. Sugary Snacks and Beverages

Sugary snacks and drinks might provide a quick energy boost, but they can lead to a rapid spike and subsequent crash in blood sugar levels. Consuming high amounts of sugar can result in insulin resistance and inflammation, which are detrimental to long-term health and athletic performance. A study published in the American Journal of Clinical Nutrition found that high sugar intake is associated with increased inflammation and oxidative stress, both of which can impair recovery and performance in athletes.

2. Fried and Greasy Foods

Fried foods are typically high in unhealthy fats, which can slow digestion and cause gastrointestinal distress during running. Foods such as french fries, fried chicken, and doughnuts can also contribute to inflammation and poor cardiovascular health. According to research in the British Journal of Sports Medicine, consuming a diet high in unhealthy fats can negatively impact endurance and increase the risk of developing heart disease, a critical concern for endurance athletes.

3. Processed Meats

Processed meats like sausages, bacon, and deli meats are high in saturated fats, sodium, and preservatives. These can lead to increased blood pressure, inflammation, and a higher risk of chronic diseases. The World Health Organization classifies processed meats as Group 1 carcinogens, indicating a direct link to cancer. For runners, the high sodium content can also lead to dehydration, especially when consumed before a run.

4. Alcohol

While occasional moderate consumption of alcohol might not be harmful, regular or excessive intake can severely impact a runner’s performance and recovery. Alcohol dehydrates the body, impairs muscle recovery, and reduces the quality of sleep. According to a study in the Journal of Applied Physiology, alcohol can significantly delay muscle recovery and decrease muscle protein synthesis, essential for muscle repair and growth.

5. High-Fiber Foods Before a Run

While fiber is an important part of a balanced diet, consuming high-fiber foods right before a run can cause gastrointestinal discomfort, including bloating, gas, and cramping. Foods like beans, lentils, and certain vegetables can be tough on the digestive system during physical activity. A study in the International Journal of Sports Medicine suggests that athletes should avoid high-fiber foods before exercise to prevent gastrointestinal issues that can impede performance.

6. Artificial Sweeteners

Artificial sweeteners, found in many diet sodas and sugar-free snacks, can cause digestive problems for some runners. These sweeteners can lead to bloating, gas, and diarrhea, which are particularly problematic during a run. Research in the Journal of Gastroenterology highlights that artificial sweeteners can disrupt gut microbiota and cause gastrointestinal distress, impacting overall digestive health.

7. Dairy Products (For Some)

While dairy is a good source of calcium and protein, it can cause gastrointestinal discomfort for some runners, especially those who are lactose intolerant. Consuming dairy before a run can lead to stomach cramps, bloating, and diarrhea. A review in the Journal of the International Society of Sports Nutrition points out that athletes with lactose intolerance should avoid dairy products close to training or competition to prevent gastrointestinal issues.


Runners need to be mindful of their dietary choices to ensure optimal performance and recovery. Avoiding sugary snacks and beverages, fried and greasy foods, processed meats, excessive alcohol, high-fiber foods before runs, artificial sweeteners, and dairy (for those who are intolerant) can help prevent potential health issues and enhance running performance. By making informed nutritional choices, runners can fuel their bodies more effectively and achieve their running goals.

1. American Journal of Clinical Nutrition. (2015). High sugar intake and its effects on inflammation and oxidative stress.

2. British Journal of Sports Medicine. (2016). Impact of high-fat diets on endurance and cardiovascular health.

3. World Health Organization. (2015). Processed meats and cancer risk.

4. Journal of Applied Physiology. (2010). Alcohol consumption and its effects on muscle recovery.

5. International Journal of Sports Medicine. (2014). Fiber intake and gastrointestinal discomfort in athletes.

6. Journal of Gastroenterology. (2018). Effects of artificial sweeteners on gut microbiota and gastrointestinal health.

7. Journal of the International Society of Sports Nutrition. (2013). Lactose intolerance in athletes and its impact on performance.

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