Sustained Energy Levels: How to Control Blood Sugar to Fuel Your Workout

sustained energy levels

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Fueling your workout with the right types of food at the right time can make all the difference when it comes to sustaining energy levels during exercise. Carbohydrates are a vital component of any successful exercise routine, and understanding the best timing for carb ingestion can be the key to getting the most out of your workout. In this blog post, we'll discuss the benefits of timing carbohydrate ingestion before and during exercise, and how to avoid the energy crash (aka reactive hypoglycemia) from eating too many carbs at the wrong time. With this information, you'll be able to create a fueling plan that helps you stay energized throughout your workout.

What is Reactive Hypoglycemia? 

what is insulin

Reactive Hypoglycemia is a condition characterized by low blood sugar levels that occur after eating a meal high in carbohydrates. When we consume a large amount of carbs, our body releases insulin to help regulate blood sugar levels. However, sometimes the glucose spike is so great that the body overreacts and releases too much insulin, causing blood sugar levels to drop too low.  Think of it like making pancakes. You have flour and water. If you accidentally spill too much flour into the bowl then you need more water. But if you add to much water then the batter is too runny. Eventually you dial in the mixture for the perfect consistency. Glucose and insulin function in a similar manner. They work together to maintain balanced blood sugar levels. However, if sometimes we eat too many carbs then insulin tries to guess how much it needs to release and sometimes it overshoots.

The symptoms of reactive hypoglycemia can vary but commonly include fatigue, shakiness, dizziness, and difficulty concentrating. These symptoms can be disruptive to your workout routine and hinder your performance.

To avoid reactive hypoglycemia and maintain stable energy levels during exercise, it's important to be mindful of when you eat carbs. Timing is key. Ideally, you should aim to eat a balanced meal that includes carbohydrates, protein, and fats about 3 hours before your workout. This allows enough time for digestion and nutrient absorption, providing your body with a steady supply of energy. As your workout time nears, optimal fueling will be determined by your exercise needs and fueling history (have you eaten or worked out earlier that day).

Understanding how your body reacts to carbohydrates and timing your carb intake appropriately can make a significant difference in your workout performance. By avoiding reactive hypoglycemia and fueling your body properly, you'll have the sustained energy you need to power through your workouts without bonking or “hitting the wall.”

Understanding the Role of Carbohydrates in Exercise

carbohydrates during exercise

Carbohydrates play a crucial role in exercise performance. When we consume carbohydrates, our body breaks them down into glucose. When we perform low-intensity exercise like walking, jogging, casual bike riding, or casual pickleball, the body predominantly utilizes fat as fuel. We can adequately perform all of the aforementioned exercises without eating extra carbs. However, as the intensity of our workout becomes greater and we progress to running, sprinting, interval cycling, tennis, and soccer, our body needs a faster source of energy to keep up with the demand for fuel. This source of energy comes from carbohydrates.  In some cases, this means preparing by eating some extra carbs before working out and/or supplementing with carbs during a workout.  

By eating carbs before high-intensity exercise, you are replenishing glycogen stores in your muscles. Glycogen is the storage form of glucose in our muscles and serves as a readily available energy source during exercise. By having ample glycogen stores, you can power through your workout without feeling fatigued too quickly. This is particularly helpful for events in which you may burn through the glucose that is circulating in the bloodstream and are not able to consume food while you workout.

In addition to providing energy, carbohydrates also spare protein. When our body runs out of carbohydrates, it turns to protein as an energy source. This can lead to muscle breakdown and hinder muscle growth and repair. By ensuring that you have enough carbs before your workout, you are preserving your muscle mass and promoting better recovery.  The trick is to find the balance between having enough carbs to fuel your workout and spare protein without overdoing it to the point where we feel sluggish or cause unnecessary glucose spikes (and reactive hypoglycemia).

Timing is Key: Pre-exercise Carbohydrate Ingestion 

pre workout foods

Timing is key when it comes to pre-exercise carbohydrate ingestion. Knowing when to eat carbs before your workout can make a significant difference in your energy levels and performance. So, let's dive into the importance of timing and how it can fuel your workout.

For the 24 to 48 hours before competition reduce your fiber intake to 1 to 2 servings. While consuming fiber is a great way to stabilize blood sugar between competitions, fiber increases the risk of gastrointestinal distress during exercise and the last thing any active individual needs is stomach issues. It can also slow down the release of non-fibrous carbs (like glucose) that we need to fuel our exercise.  The exception to this rule is if you are exercising in the heat, consume a bit of fiber with your meal approximately 3 hours before competition. A bit of fiber helps to protect the lining of the gut from heat-stress injury.

When it comes to the day of competition, ideally, you should fuel up with a balanced meal that includes carbohydrates about 3 hours before your exercise session. This allows enough time for digestion and absorption, ensuring that your muscles have a steady supply of fuel. The inclusion of protein and fat in the meal will help to stabilize blood sugar levels but still consume some carbohydrates. By eating some carbs before exercise, you're replenishing your glycogen stores, which are the storage form of glucose in our muscles. This readily available energy source will help you power through your workout without feeling fatigued too quickly.  This is also a great time to drink a GOOD IDEA. It will help you stabilize blood sugar levels in order to sustain the energy from the meal and not feel sluggish before your workout.  

Eating throughout the day (as opposed to cramming your carbohydrates into a short window of time) also helps prevent the onset of reactive hypoglycemia. By providing your body with a steady supply of carbohydrates, you can avoid the sudden drop in blood sugar levels that can cause symptoms like fatigue, shakiness, and difficulty concentrating.

However, if you were not able to eat throughout the day or if you are about to perform high-intensity exercise, then consuming some fast-absorbing carbohydrates approximately 15 to 30 minutes before exercise can help to power those bursts of energy you need at the start of a competition. However, avoid eating approximately one hour before exercise. This timing gives your blood sugar enough time to spike and dive before the start of your workout; leaving your energy levels running on empty when you need them the most.   

A note about carb loading. The carbohydrate intake guidelines outlined in this blog do not constitute carbohydrate loading. Carb loading is a completely different process that is specifically utilized for high-intensity exercise lasting longer than 90 minutes. While the details of how to properly carb load will be covered in a future blog, it is a procedure that is unnecessary for any recreational athlete but can be extremely beneficial for elite athletes.

Do you Need Carbs Mid-Workout: Calculating your Carb Needs

food during workout

When it comes to fueling your workout, timing is important, but so is knowing how much to eat. Calculating your carb needs can ensure that you have the right amount of fuel to power through your exercise routine without feeling sluggish or fatigued.

So, how do you determine how much to eat? It depends on several factors, including the duration and intensity of your workout, your body weight, and your overall fitness goals. Training volume dictates carb consumption because the more frequently we work out, the more fuel we need to power our muscles. Likewise, training intensity drives carbohydrate consumption. High-intensity exercise predominantly relies on carbohydrates, whereas low-intensity workouts, like recovery bike rides or runs, can be completed utilizing mostly endogenous fat as fuel.

Short Workouts

Short (less than 45 min) and high intensity workouts are incredibly efficient.  Interval workouts are a popular option for individuals short on time that want to maximize cardiovascular benefits.  The high intensity can be identified when you are breathing heavily enough that you are unable to chat with our workout buddy. You should be able to get through this short of a workout without any additional mid-workout food.  The caveat is if you are fasted (including an overnight fast) or on a ketogenic diet, then additional fuel might be needed to power those high intensity bursts throughout the workout. 

Long Workouts

High intensity exercises lasting longer than 75 minutes can usually benefit from taking on some extra carbs in order to sustain your energy levels and avoid “hitting the wall.”  “Hitting the wall” is a state in which your fuel reserves are depleted and you are unable to produce energy fast enough to maintain exercise intensity.  Unfortunately, most individuals are unaware that their fuel reserves are getting low until they have reached this rock-bottom.  To avoid this state, when your workout lasts longer than 75 minutes (especially if it exceeds two hours) aim to consume 30-60 grams of carbohydrate per hour.  Preferably these carbs will come from glucose as opposed to fiber to quickly provide energy to your muscles.  If you prefer liquid carbohydrates then shoot for ingestion at 15-20 min intervals throughout exercise.

Additionally, it's important to listen to your body and adjust your carb intake accordingly. If you find that you're feeling sluggish or low on energy during your workouts, you may need to increase your carbohydrate intake. On the other hand, if you're feeling overly full or bloated, you may need to decrease your carb intake.

Remember, finding the right balance of carbohydrates for your individual needs may take some trial and error. But with practice and attention to your body's signals, you'll be able to determine the ideal amount of carbs to eat before exercise, helping you reach your fitness goals and have the energy you need for a successful workout.

Foods to Choose for Sustained Energy

foods to sustain energy

When it comes to fueling your workout for sustained energy, the types of foods you choose are just as important as the timing. Eating the right foods before and during exercise can ensure that your body has a steady supply of energy to power through your workout.

Before your Workout

For your meal approximately 3 hours before a workout opt for a balanced meal with a protein source (lean beef, chicken, eggs, yogurt, fish if it sits well with your stomach), a bit of healthy fat (avocado, almonds, walnuts), and some carbs (potatoes, cereal, some fruits, pasta). This is also a great time to drink a GOOD IDEA. It will help you stabilize blood sugar levels in order to sustain the energy from the meal and not feel sluggish before your workout.  

During your Workout

To sustain your energy levels in the middle of a high-intensity workout focus on predominantly glucose. Fruits like grapes, watermelon, cherries, and dates are all great snacking options. Fig bars and bananas are also healthy exercise options.

If you are hungry in the middle of a lower-intensity workout then pair any of the options above with a GOOD IDEA. The glucose in the carbs will be able to provide you with a bit of fuel and satisfy your hunger. However, since your workout is a lower intensity, it won’t need all that fuel at once. By delaying gastric emptying, GOOD IDEA allows the energy from those carbs to be slowly released into the blood stream, where it can be used at a more appropriate rate.

Actionable Next Steps

what to eat to sustain energy

Timing your carbohydrate intake before exercise can make a world of difference in your workout performance and energy levels. By understanding the role of carbohydrates in exercise and the potential risks of reactive hypoglycemia, you can create a fueling plan that supports your fitness goals.

Eating carbohydrates before exercise provides your muscles with a steady supply of fuel, replenishing glycogen stores and preventing the onset of reactive hypoglycemia. Aim to consume a balanced meal that includes carbohydrates, protein, fats, and potentially a GOOD IDEA, about 3 hours before your workout for optimal digestion and absorption.

When it comes to the amount of carbs to eat, consider factors such as the duration and intensity of your workout. Finding the right balance may take some trial and error, but listening to your body and adjusting accordingly will help you find the ideal amount of carbs for your individual needs.

By following these guidelines and paying attention to your body's needs, you'll have the sustained energy and support to power through your workouts and achieve your fitness goals. So, go ahead and fuel up with the right carbs at the right time and watch your workout performance soar!


Author: Dr. Colleen Gulick