Eating While Exercising: When It's Beneficial, What to Eat, and When to Avoid It

Can I eat while exercising?

While it's generally not recommended to consume solid food during most typical workouts due to digestive distress and redirected blood flow, strategic nutrient intake can be beneficial and even necessary during prolonged endurance activities to sustain performance.

The Short Answer: It Depends

The question of eating while exercising is nuanced, with the optimal approach heavily dependent on the duration, intensity, and type of physical activity, as well as individual physiological responses. For most recreational exercisers engaging in sessions under 60-90 minutes, consuming food during the activity is rarely necessary and often counterproductive. However, for endurance athletes undertaking multi-hour events, strategic intra-workout fueling becomes a critical component of performance and recovery.

Understanding Energy Systems and Digestion During Exercise

To understand the implications of eating during exercise, we must first consider the body's energy demands and digestive processes.

• The Digestive Process: When you eat, your body initiates a complex digestive process that requires significant blood flow to the gastrointestinal (GI) tract to break down food and absorb nutrients.
• Energy Demands of Exercise: During exercise, particularly moderate to high intensity, blood flow is redirected away from the digestive organs and towards the working muscles, heart, and lungs. This physiological shift is crucial for oxygen and nutrient delivery to sustain muscular work.
• The Conflict: Attempting to digest food during exercise creates a conflict for blood flow. Reduced blood flow to the GI tract impairs digestion, leading to potential discomfort, while increased blood flow to the GI tract could compromise oxygen delivery to muscles, potentially hindering performance.

When Eating During Exercise Might Be Beneficial (and What to Eat)

For specific types of exercise, particularly those that deplete glycogen stores, intra-workout fueling can be advantageous.

• Endurance Sports (Long Duration): Activities lasting longer than 90 minutes, such as marathons, ultra-running, long-distance cycling, or triathlons, significantly deplete muscle and liver glycogen stores. In these scenarios, consuming exogenous carbohydrates can help maintain blood glucose levels, spare glycogen, and delay fatigue.
• High-Intensity, Prolonged Activities: Certain team sports or continuous intense activities exceeding an hour may also benefit from mid-activity carbohydrate intake, though often in liquid form.

What to Eat (and What to Avoid): When intra-workout fueling is necessary, the focus should be on easily digestible carbohydrates that provide quick energy without causing GI distress.

• Simple Carbohydrates: Glucose, fructose, and maltodextrin are preferred. These are rapidly absorbed and converted into energy.
• Low Fiber, Low Fat, Low Protein: Avoid foods high in fiber, fat, and protein during exercise, as these components slow digestion and can lead to bloating, cramping, and nausea.
• Recommended Options:
  • Sports Gels and Chews: Designed for rapid absorption, providing concentrated carbohydrates.
  • Diluted Sports Drinks: Offer carbohydrates and electrolytes, aiding both fuel and hydration.
  • Bananas or Dried Fruit: Natural sources of simple sugars, though some may find the fiber content in larger quantities problematic.
  • White Bread or Pretzels: For longer events, these can offer a digestible carbohydrate source.

General Guideline: For activities over 90 minutes, aim for 30-60 grams of carbohydrates per hour, often delivered in small, frequent doses.

When Eating During Exercise is Generally Not Recommended

For the vast majority of exercise sessions, eating solid food mid-workout is unnecessary and can be detrimental.

• Short Duration/Moderate Intensity Workouts (Under 60-90 minutes): Your body has sufficient glycogen stores to fuel these sessions. Focus on adequate pre-workout nutrition and post-workout recovery.
• Strength Training: The primary energy system for resistance exercise is the phosphocreatine system and anaerobic glycolysis, which do not rely on a continuous influx of external carbohydrates during the session. Eating during strength training can lead to discomfort without significant performance benefits.
• High-Intensity Interval Training (HIIT): The stop-and-go nature and high intensity of HIIT increase the risk of GI distress if food is consumed.
• The Risks:
  • Gastrointestinal Distress: Nausea, cramping, bloating, diarrhea, or indigestion are common due to compromised digestion.
  • Reduced Performance: Discomfort can distract from the activity and even force cessation.
  • Aspiration Risk: Eating while breathing heavily can increase the risk of choking.

Optimizing Your Intra-Workout Nutrition Strategy

If your activity duration warrants intra-workout fueling, consider these strategies:

• Listen to Your Body: Individual tolerance to food during exercise varies significantly. What works for one athlete may not work for another.
• Practice in Training: Never try new foods or fueling strategies on race day or during a critical performance. Experiment with different options during your training sessions to determine what your body tolerates best.
• Hydration is Key: Often more critical than solid food, especially for sessions under 2 hours. Ensure adequate fluid and electrolyte intake.
• Timing of Intake: If consuming carbohydrates, do so in small, consistent amounts rather than large boluses to minimize GI upset and maintain steady energy levels.
• Consider Liquid vs. Solid: Liquid carbohydrate sources (sports drinks) are often better tolerated and absorbed more quickly than solid foods during high-intensity or prolonged efforts.

Key Takeaways for Intra-Workout Fueling

For most individuals engaged in typical fitness routines, eating during exercise is not recommended. The body's physiological response to exercise prioritizes muscle function over digestion, making food intake potentially uncomfortable and counterproductive.

However, for endurance athletes pushing beyond 90 minutes, strategic intake of easily digestible carbohydrates is a cornerstone of sustained performance. Always prioritize listening to your body, practicing your fueling strategy in training, and focusing on proper hydration.