Fueling Your Workout: What to Eat Before a Workout to Keep Blood Sugar Up

December 27, 2025 •

4 min read

According to the American Diabetes Association, proper pre-workout nutrition is critical for maintaining stable blood sugar and avoiding hypoglycemia during exercise. Fueling your body correctly provides the necessary glucose for energy, preventing crashes that can derail your workout and overall health.

Quick Summary

This guide provides practical and effective strategies for choosing the right foods to eat before a workout to keep blood sugar up. It details the best combinations of carbohydrates, protein, and fats based on timing and intensity to maximize energy and performance.

Key Points

Balance Carbs and Protein: Combine complex carbohydrates with lean protein in your pre-workout meal to ensure a slow, steady release of glucose into the bloodstream.
Timing is Everything: Eat a larger, balanced meal 2-3 hours before, a moderate snack 1-1.5 hours before, or a small, high-carb snack 30-60 minutes before your workout for optimal digestion and energy.
Prioritize Complex Carbs: Opt for sources like oatmeal, whole-grain bread, and sweet potatoes, which provide sustained energy and prevent sudden blood sugar spikes.
Include Healthy Fats (Moderately): Small amounts of healthy fats from nuts or avocado can contribute to long-lasting energy, especially for longer, low-intensity exercise, but avoid excessive amounts too close to your workout.
Stay Hydrated: Drink plenty of water before, during, and after exercise, as dehydration can negatively impact blood sugar levels and performance.
Listen to Your Body: Use trial and error to find the best pre-workout meals and timings that suit your personal metabolism and digestive rate.

The Importance of Pre-Workout Fuel for Blood Sugar

Maintaining stable blood sugar, or glucose, is crucial for anyone engaging in physical activity, but it is especially important for individuals with diabetes or those prone to hypoglycemia. Glucose is the body's primary fuel source during exercise, particularly for moderate to high-intensity activities. Without adequate fuel, blood sugar levels can drop too low, leading to fatigue, dizziness, and impaired performance. Conversely, for certain high-intensity workouts like heavy weightlifting, the body releases stress hormones like adrenaline, which can temporarily increase blood glucose levels. Proper pre-workout nutrition helps manage these fluctuations, ensuring a steady energy supply and a more effective and safer workout session.

The Role of Macronutrients in Pre-Workout Meals

To build the perfect pre-workout meal or snack, you must understand the roles of each macronutrient:

Carbohydrates: Your body's primary energy source. They are broken down into glucose and stored as glycogen in your muscles and liver.
Protein: Essential for muscle repair and growth. It helps slow the absorption of carbohydrates, which prevents rapid blood sugar spikes.
Healthy Fats: Provide a sustained, long-term energy source, particularly for longer, lower-intensity workouts. However, they digest slowly, so consuming too much right before a high-intensity session can cause stomach upset.

Timing Your Pre-Workout Meal

Timing is one of the most critical factors in pre-workout nutrition, as it dictates the ideal balance of macronutrients.

Eating 2-3 Hours Before a Workout

For those with enough time for a substantial meal, this is the optimal window. The goal is to consume a balanced meal with complex carbohydrates, lean protein, and a small amount of healthy fat to provide lasting energy.

Grilled chicken breast with brown rice and steamed vegetables.
Quinoa bowl with black beans, avocado, and salsa.
Omelet with eggs, vegetables, and a side of whole-grain toast.

Eating 1-1.5 Hours Before a Workout

This timeframe is best for a smaller, carb-focused meal that is easier to digest. You still want some protein to aid in blood sugar stabilization.

Oatmeal with berries and a spoonful of nuts.
Whole-grain toast with almond or peanut butter.
Greek yogurt with fruit and a sprinkle of low-fat granola.

Eating 30-60 Minutes Before a Workout

For a quick fuel-up, choose easily digestible, high-carb snacks. The focus here is on readily available energy without weighing you down.

A banana with a tablespoon of nut butter.
A small piece of fruit like an apple or orange.
A small handful of raisins and nuts.

Comparison Table: Pre-Workout Fuel Options


Food/Meal	Primary Macronutrient	Timing Before Workout	Benefits for Blood Sugar
Oatmeal	Complex Carbohydrates	1-2 hours	Slow digestion prevents spikes, provides sustained energy
Greek Yogurt	Protein, Carbohydrates	30-60 minutes	Protein slows carb absorption for steady glucose release
Banana with Nut Butter	Carbs, Healthy Fat, Protein	30-60 minutes	Quick energy from banana, balanced by nut butter's protein and fat
Sweet Potato	Complex Carbohydrates	1-2 hours	High-fiber, sustained energy release
Scrambled Eggs on Whole-Grain Toast	Protein, Complex Carbohydrates	1-2 hours	Slower-digesting combo for long-lasting fuel

Sample Pre-Workout Meal Ideas

Smoothie for Quick Energy: Blend a banana, a scoop of protein powder, a handful of berries, and milk (dairy or plant-based). This is excellent for a quick, digestible option within an hour of exercise.
Power Oatmeal: Prepare 1/2 cup of cooked oats with 1/4 cup of berries and a tablespoon of mixed nuts. This is a solid, sustained energy source for a workout 1-2 hours later.
Avocado Toast: Mash 1/4 avocado onto a slice of brown rice bread. This provides carbs and healthy fats for a moderate workout 30-60 minutes away.
Small Meal: For a workout 2-3 hours away, a lean turkey sandwich on whole-grain bread with lettuce and tomato is a balanced and effective option.

Other Considerations for Stable Blood Sugar

In addition to the right food, several other factors contribute to maintaining steady blood sugar during exercise.

Hydration is Key

Drinking enough water is essential for optimal performance and helps regulate blood glucose levels. Dehydration can negatively impact blood sugar and performance. Be sure to hydrate well before, during, and after your workout.

Workout Intensity Matters

The type and intensity of your exercise affect your fueling needs. High-intensity, short-duration exercise may require a quicker-acting carb source, while long-duration, low-intensity workouts benefit from slower-digesting, complex carbs and some fat.

Listen to Your Body

Everyone's metabolism is unique. It's crucial to experiment with different foods and timings to see what works best for your body. Keeping a food and workout journal can help you identify patterns and optimize your fueling strategy.

Conclusion: Fuel Smart, Perform Better

Choosing what to eat before a workout to keep blood sugar up is about balancing timing, intensity, and the right mix of macronutrients. Prioritizing complex carbohydrates for sustained energy, pairing them with lean protein to stabilize glucose, and being mindful of fat intake can make a significant difference in your workout performance and overall energy levels. Remember to stay hydrated and listen to your body's signals to find the perfect fueling strategy for your individual needs. By fueling smart, you can power through your workouts effectively and avoid the energy crashes that come with unstable blood sugar.

Note: Individuals with diabetes or other specific health conditions should consult with a healthcare provider or a registered dietitian to develop a personalized nutrition plan for exercise.

Frequently Asked Questions

Complex carbohydrates like oatmeal, whole-grain bread, and sweet potatoes are best for sustained energy. They break down slowly, providing a steady release of glucose that helps keep blood sugar levels stable throughout your workout.

The ideal timing depends on the size of your meal. Aim for a full meal 2-3 hours before, a small snack 1-1.5 hours before, or a very light snack 30-60 minutes before exercising.

Yes, a protein shake can be a quick and effective pre-workout snack, especially when combined with a fast-digesting carbohydrate like a banana or berries. This provides both quick energy and muscle support.

While healthy fats can provide long-term energy, they are slow to digest. It's best to limit high-fat foods in the 1-2 hours before intense exercise to avoid stomach discomfort or feeling sluggish.

If your blood sugar is below 100 mg/dL, consume a small snack with 15-30 grams of fast-acting carbs, such as a piece of fruit or some juice, before starting. Always have quick-acting sugar (like glucose tablets) on hand if you are prone to hypoglycemia.

Yes, a banana is an excellent pre-workout snack, especially if you have less than an hour. It contains easily digestible carbohydrates for a quick energy boost and is also a good source of potassium.

Yes, proper hydration is crucial. Dehydration can negatively impact blood sugar levels and overall performance. Make sure to drink plenty of water before, during, and after your workout.