Refueling During Workouts: Necessary or Not?

It's the bottom of the sixth inning, mile seven in your half marathon, or halfway through the toughest Crossfit workout you've ever done -- and you need to refuel. Or do you?

Whether you're a professional athlete, someone who stays active for health reasons, or somewhere in between, how you should refuel during a workout -- and whether you need to do so at all -- is highly individual. What foods should you be focusing on when refueling during workouts? Do you choose real foods or utilize sports gels, gummies, drinks, and bars? It all depends on what type of exercise you're doing, how much of it you're performing, and what works for you personally.

Let's take a closer look at some of the parameters to think about when deciding whether and how to refuel midworkout so you can start to test things out for yourself.

Level of Activity

Determining your activity level is key in assessing your need to take in fuel during workouts. Generally speaking, the different levels of activity include:

Generally, you'll only need to consider midworkout fuel if you're taking on a high- or very-high-level activity.

Carbohydrates

During exercise, your body will initially use your carbohydrate stores for energy. As you settle into the workout, you'll start to tap into your fat stores, as well. There's relatively little carbohydrate stored in your body compared to fat, and those carbs will be depleted rapidly during endurance exercise. Nevertheless, carbohydrate remains the preferred source of energy during workouts because it can produce more energy per unit than fat and at a quicker rate.

It's been accepted for some time that maintaining carbohydrate availability can sustain high-intensity exercise performance. Conversely, depletion of carbohydrate stores during endurance exercise is associated with fatigue, impaired concentration and skill, and increased work perception. Thus, when refueling during workouts, you'll want to focus on carbs.

Your Midworkout Needs

Your needs for midworkout fuel depend upon the intensity and duration of the activity. If you're performing low-intensity exercise, you probably don't need any fuel during your workout, but you may need quite a bit if you're undertaking long, intense efforts. Here's an overview of how much carbohydrate you should take in depending on the type of exercise you're doing.

Best Carbohydrate Choices

When choosing a midworkout source of carbohydrate, there are a number of factors to consider. Your fuel source should contain little or no fat and protein, as these macronutrients will slow down the digestion and delivery of glucose.

Additionally, seek out predominantly simple carbohydrate sources; these will be digested faster than complex carbs such as fruit, vegetables, and whole grains. Simple carbs contain sugar and starch with very little fiber: Think fruit juice, honey, and sports energy products (drinks, gels, and bars).

Endurance athletes gravitate toward gels and drinks because they contain electrolytes, are easy and quick to consume, and aren't likely to upset your stomach once you're accustomed to them. Some prefer gels or gummies over drinks because they can't tolerate large volumes of liquid while exercising. Also, you'll notice that your needs during endurance exercise will be in multiples of 30 grams of carbohydrate, and sports energy products tend to mesh with those numbers nicely.

Hydration

One reason to consider a sports drink over gummies and gels is that a liquid fuel source helps with hydration. During long, intense efforts, you should drink enough fluids to replace the sweat you're losing.

You can find out how much you typically sweat by weighing yourself before and after exercise. Every kilogram (approximately two pounds) of sweat you lose should be replaced by one liter (or 32 ounces) of fluid. For endurance athletes, this typically breaks down to about a half liter per hour. If you tend to sweat large amounts (more than one liter per hour) or you're exercising for longer than two hours, you should also take in some sodium while you hydrate.

Refueling midworkout is one of the few times when a dietitian might recommend processed over whole foods -- products designed for athletic pursuits are more efficient and less likely to upset your stomach. But as you can see, taking in fuel while exercising is really only necessary for hard-charging athletes during long, intense efforts.

However, while you may not need to refuel during your workout, you almost certainly need to stay hydrated, especially during the warmer months.