Eating and Drinking During Exercise: What to Do and What to Avoid

Woman drinking water at the gym

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Nutrition is arguably the most crucial factor in seeing results from your fitness endeavors. How you fuel and hydrate your body drastically influences how you perform and recover from exercise. This includes cardiovascular and weight training.

While how much and what you eat will likely differ based on your goals and the type of training you do, there are fundamental nutritional best practices that serve anyone performing physical activity. For instance, fueling your workouts themselves, providing nourishment for your body to repair and recover, and meeting the basic needs of your body.

Below, you will discover when is best to eat and drink during exercise, what types of food and hydration you should choose, and what is best to avoid.

When You Want to Eat and Drink During Exercise

Eating and drinking during exercise are not always necessary. Most people will do best without eating during training since digestion does not function well due to reduced blood flow to the organs. This effect can make people feel nauseous.

However, for those performing higher-intensity or more prolonged exercise, some caloric intake could help you get through the training session without feeling too much fatigue. If you are performing a long-distance endurance workout, intra-workout fluids, electrolytes, and carbohydrates are essential to optimize performance. For strength-based workouts, eating is likely unnecessary unless your session is longer than 60 to 90 minutes.

Eating too close to a workout can also result in nausea and gastrointestinal upset. For this reason, it is best to consume a meal about 4 hours before a hard workout and if necessary, stick to an easily digestible carbohydrate or carbohydrate and protein snack at least 60 minutes before your workout. Eating too close to a workout can also result in nausea and gastrointestinal upset.

When performing longer workouts, adding an easily digestible carbohydrate and/or protein source can be beneficial. What you choose to consume can be based on your goals. For instance, to perform at your best during endurance exercise, be sure to include carbohydrates.

If you aim to build muscle, both a protein and carbohydrate source before and after your training session is ideal. During your performance, adequate carbohydrate intake may facilitate the muscles to adapt and grow from each exercise session, improving your results. The same is valid for protein consumed soon after your workout, so if you prefer to wait until your training session is over, you can reap the same benefits.

What to Eat (and How to Time It)

The fuel your body uses to perform exercise comes from glycogen stores in your muscles. Your body uses this stored glycogen first, but if it becomes depleted during your training, it is forced to pull energy from the sugars in your liver and blood. Once this is gone, your body can convert fat stores and eventually protein to fuel your activity.

For workouts lasting longer than 90 minutes, consuming carbohydrates, electrolytes, and fluids during training is ideal for replenishing glycogen stores and dehydration prevention. This re-fueling is especially important for anyone who aims to improve performance, build muscle, or increase fitness levels.

While using fat stores for fuel may sound appealing if you want to lose fat, this is not ideal. When your body is depleted of easily accessible fuel in the form of glycogen, you will not be able to train as intensely or effectively, resulting in a lower calorie burn than you could otherwise achieve. When all is balanced, you will not have created as large of a calorie deficit as you would have had you fueled yourself before training.

Since digestion can be blunted during exercise, relying on a liquid fuel such as an intra-workout shake is wise. However, some people prefer to consume whole foods. In this case, choosing easily digestible, high-glycemic carbohydrates and easily digestible protein sources are best. Foods to try include:

  • Bananas
  • Energy bars or gels
  • Grapes
  • Dried fruit (dates, raisins, dried cranberries)
  • White bread
  • Watermelon
  • Cereal
  • White rice
  • Whey protein powder
  • Amino acid supplements
  • Plant-based protein powder

Consuming carbohydrates alone or combined with protein during resistance training increases muscle glycogen stores, mitigates muscle damage, and encourages your muscles to adapt to training, providing better results.

What to Drink (and How to Time It)

Drinking your nutrition during a workout is likely the optimal solution to adding carbohydrates and protein to your training. Beverages are typically more readily digested and quick to absorb. Sources of carbohydrates and protein are easily accessible in powder form to be mixed with liquid.

Aside from carbohydrate and protein intake, hydration is crucial for your health and safety during prolonged and intense exercise. The amount you should drink during training depends on how long you will be training and your personal sweat rate.

Studies suggest a personalized hydration plan that takes your sweat loss into account. The position of the American College of Sports Medicine (ACSM) agrees that personalized hydration is the optimal route.

The ACSM recommends consuming fluids regularly throughout your training session. The amount is based on several personal factors, including your clothing, the environment, and the length and intensity of your training. The ACSM recommends electrolyte and carbohydrate-containing beverages be consumed to balance fluid and electrolytes and increase performance.

Start with 0.4 to 0.8 liters of fluid per hour, using the higher end range for more intense exercise for heavier individuals performing in warm or humid conditions. The lower end is for slower, lighter individuals in cooler climates.

What to Avoid

During exercise, the sympathetic nervous system becomes activated. This part of the nervous system is responsible for the "fight or flight" response. As mentioned, this effect leads to blood circulation being directed to the heart, lungs, and skeletal muscles, with reduced blood flow to the organs responsible for digestion.

With intense and prolonged exercise, sustained reduction of blood flow to the bowel can result in inflammation and increased intestinal wall permeability. Gut permeability can lead to food intolerances, sensitivities, and other gastrointestinal issues.

For these reasons, it is best to avoid eating or drinking anything heavy or hard to digest, especially fats and fiber, which slow gastric emptying, leaving undigested food in your stomach, leading to nausea and stomach upset.

More difficult-to-digest proteins such as meat and other whole food sources are also best avoided during exercise. If you wish to add protein to your intra-workout nutrition, stick to easily digestible sources such as whey or vegan protein powders or an amino acid supplement.

Foods to Avoid During Workouts

  • Whole grains and whole grain products
  • High fat foods including full-fat dairy and nuts
  • Meat and poultry
  • High fiber fruits

A Word From Verywell

It is essential that you listen to your body's cues, properly nourishing your body as you feel best. This includes your pre, post, and intra-workout nutrition habits. However, there are some best practices to follow that will help ensure you feel your best while obtaining the results you desire. Seek help from a medical professional if you have any questions about nutrition or fitness goals. 

Frequently Asked Questions

  • Is it OK to workout on an empty stomach? 

    It is ok to work out on an empty stomach, in fact, it may be best to have a relatively empty stomach to avoid gastric upset during training. However, you should ensure that you've eaten enough 1 to 2 hours prior to training that you are energized and fueled for your workout and recovery.

  • How much should I drink during exercise? 

    How much you drink during exercise depends on the type of exercise and the duration, as well as climate, body size, and several other factors. You can try a range of 0.4 to 0.8 liters of fluid per hour, with the low end for less intense and the higher end for more intense conditions and exercise.

  • What is a good pre-workout snack? 

    A good pre-workout snack is something relatively small and easy to digest. Try some Greek yogurt with banana, or toast with fruit spread and a whey protein shake.

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