The Science of Fueling Your Workout
Eating a snack during exercise is not only acceptable but often beneficial, especially for workouts that last longer than 60 to 90 minutes. Your body relies on glycogen—a stored form of glucose from carbohydrates—as its primary fuel source during moderate to high-intensity activity. As these glycogen stores become depleted, fatigue sets in, and performance can suffer significantly. A strategically timed snack helps to replenish these stores, allowing you to sustain intensity and prolong endurance. For shorter, lower-intensity workouts, pre-workout fueling is generally sufficient, and mid-session snacks are not necessary.
Carbohydrates: The Key to Intra-Workout Fuel
The most important macronutrient to consume during extended exercise is carbohydrates. Simple carbohydrates are best as they are digested and absorbed quickly, providing a fast energy boost to your working muscles. This is why sports gels, chews, and simple fruits are popular among endurance athletes. Protein and fat, while essential for overall nutrition, are slower to digest and can cause stomach upset or discomfort if consumed mid-workout. The goal is to provide your body with easily accessible fuel without diverting too much blood flow to the digestive system.
Best and Worst Snacks for Mid-Workout
Choosing the right snack is critical to reaping the benefits without experiencing adverse side effects like cramps or nausea. The ideal snack should be portable, easy to eat, and primarily carbohydrate-based. For example, a banana is a well-known, natural option that provides both quick-acting sugars and potassium, an important electrolyte lost through sweat.
Comparison Table: Ideal vs. Ineffective Intra-Workout Snacks
| Feature | Ideal Intra-Workout Snack | Ineffective Intra-Workout Snack |
|---|---|---|
| Primary Nutrient | Fast-digesting carbohydrates | High fat, protein, and fiber |
| Digestion Speed | Rapid, to provide quick energy | Slow, can cause stomach upset |
| Portability | Easy to carry and consume | Cumbersome or requires preparation |
| Examples | Energy gels, sports chews, banana, raisins, diluted juice | Cheeseburger, large sandwich, high-fiber granola bar |
| Benefit | Sustains energy, prevents bonking | Can cause sluggishness and discomfort |
Listening to Your Body’s Signals
Your personal tolerance and the type of exercise you are doing are the most important factors. An ultra-marathon runner’s fueling strategy will differ greatly from someone doing a 90-minute gym session. It's important to experiment during training to find what works best for your body, rather than trying a new snack during a race or an important event. If you feel symptoms of low energy like dizziness, nausea, or a sudden drop in performance, a quick, carb-rich snack might be necessary.
Proper Timing and Hydration
For sessions exceeding an hour, aim for about 30 to 60 grams of carbohydrates per hour. This can come from a combination of sports drinks and solid foods. For example, you might consume a gel every 45 minutes or have small, frequent sips of a sports drink alongside a piece of fruit. Staying hydrated is equally as important as fueling. Dehydration can impair performance and make it difficult for your body to process food, so consume water or an electrolyte drink regularly. For those exercising for more than 60 minutes, a sports drink can provide both hydration and carbohydrates.
Conclusion
Yes, you can eat snacks while exercising, but the practice is dependent on the duration and intensity of your workout. For extended, high-intensity efforts, intra-workout fueling with fast-digesting carbohydrates is a proven strategy to maintain performance and delay fatigue. For shorter, less strenuous activities, pre-workout nutrition is likely sufficient. Remember to listen to your body, choose easily digestible snacks, and stay hydrated to get the most out of your training session. When in doubt, start with a well-timed, simple carbohydrate like a banana or raisins and observe how your body responds.
For further reading on the science of sports nutrition, explore the recommendations from the International Society of Sports Nutrition (ISSN).
Frequently Asked Questions
What are some good snacks to eat during a workout?
Some great intra-workout snacks include energy gels, chews, bananas, raisins, and diluted fruit juice. These options provide fast-acting carbohydrates that are easy to digest.
Should I eat during a workout that lasts less than an hour?
For most workouts under 60 minutes, mid-session snacking is unnecessary as your body has sufficient stored glycogen from your pre-workout meal or snack. Focus on proper hydration instead.
How often should I eat snacks during a long workout?
For high-intensity endurance exercise lasting over an hour, aim to consume 30 to 60 grams of carbohydrates per hour to maintain energy levels. This can be a sports gel every 45 minutes or a combination of easy-to-digest carbs.
What foods should I avoid eating while exercising?
Avoid snacks that are high in fat, protein, or fiber, such as greasy foods, high-fiber granola bars, and large sandwiches. These can slow digestion, cause stomach upset, and lead to cramps during exercise.
Is it okay to drink a sports drink during exercise?
Yes, sports drinks are an excellent way to get both hydration and carbohydrates during prolonged exercise (over 60 minutes). They help replenish electrolytes lost through sweat.
Can snacking during a workout help me lose weight?
If your goal is weight loss, strategic snacking during long, intense workouts can help sustain your performance. However, for shorter, less intense workouts, you might benefit from fueling up before to encourage your body to use stored fat for energy.
What should I do if I get stomach cramps from a snack during exercise?
If you experience cramps, try a different type of snack. Opt for a lower-fiber, simpler carbohydrate option and make sure you are not eating too close to a high-intensity period. Experiment during training to find what your body tolerates best.
