Should Runners Eat in a Calorie Surplus? Strategic Fueling for Performance and Recovery

October 26, 2025 •

4 min read

While many runners focus on burning calories, elite endurance athletes may require over 4,500 calories per day during intense training cycles. The question of whether a runner should eat in a calorie surplus depends heavily on their specific training phase and performance goals.

Quick Summary

A moderate calorie surplus can be beneficial for runners aiming to build muscle and enhance recovery, particularly during off-season strength training or intense periods. This strategy is goal-dependent and must be managed carefully to avoid unnecessary fat gain.

Key Points

Goal-Dependent Fueling: A calorie surplus for runners is a strategic choice, not a necessity, and depends on specific goals like muscle gain or supporting intense training.
Support for Intense Training: During peak training phases for long-distance events like marathons, a surplus ensures adequate energy and prevents under-fueling, which impairs performance and increases injury risk.
Build Muscle Mass: Combining a moderate calorie surplus with resistance training is essential for runners who want to increase strength and muscle mass, which can improve running economy.
Accelerate Recovery: Eating a surplus ensures the body has the fuel to quickly repair muscle tissue and replenish glycogen stores after strenuous workouts.
Avoid Excessive Gain: A moderate surplus is key to maximizing muscle gain while minimizing unwanted fat. A large, uncontrolled surplus can negatively impact performance.
Prioritize Nutrient Quality: The source of surplus calories matters; focus on nutrient-dense whole foods rather than processed junk food to support overall health and performance.

Understanding Energy Balance for Runners

For a runner, achieving peak performance is a delicate balance of training, rest, and nutrition. An athlete's energy needs vary significantly based on their training load. Consuming the right number of calories—or having the correct 'energy balance'—is vital for fueling runs, recovering effectively, and supporting physiological adaptations.

Calorie Maintenance vs. Calorie Surplus

Calorie Maintenance: This is consuming the same number of calories that your body burns to maintain your current weight. Many active runners must eat a high volume of food just to stay at maintenance due to the high energy expenditure of their sport.
Calorie Surplus: This involves consuming more calories than your body expends. The excess energy is stored as fuel reserves (glycogen) and is also used to build and repair muscle tissue.

The Strategic Case for a Calorie Surplus

For many runners, intentionally eating more can be counterintuitive. However, a strategic calorie surplus is a powerful tool for achieving specific performance goals, especially during the right training phases.

Supporting Intense Training Cycles: During periods of high-volume training, such as marathon or ultra-training, energy demands are at their peak. A slight calorie surplus ensures the body has ample fuel to perform long runs and prevents under-fueling, which can lead to fatigue, poor performance, and increased injury risk.
Building Muscle and Strength: Running alone doesn't build significant muscle mass. Runners who incorporate resistance training need a calorie surplus to facilitate muscle protein synthesis. Combining a moderate surplus (200–400 calories/day) with strength training is essential for building lean mass and strength, which can improve running economy and reduce injury risk.
Accelerating Recovery: Recovery is when the body adapts and gets stronger. A calorie surplus ensures the body has the energy and nutrients, especially carbohydrates and protein, to repair muscle tissue and replenish glycogen stores quickly after a hard workout.
Preventing Performance Decline: Chronic under-fueling can lead to Relative Energy Deficiency in Sport (RED-S), a syndrome that impairs metabolic rate, immune function, and bone health. Eating at a small, consistent surplus can help prevent this condition in runners with high training volumes. An athlete is better off slightly over-fueled than chronically under-fueled.

When to Avoid a Calorie Surplus

A calorie surplus is not a universal recommendation for runners. It depends on your primary objective. If your main goal is to lose weight, then a moderate calorie deficit is necessary. Attempting a surplus during a weight loss phase would be counterproductive and would lead to fat gain instead of weight loss. A large, uncontrolled surplus, often referred to as a "dirty bulk," can also result in excessive fat gain that negatively impacts speed and overall performance.

Practical Steps for Managing a Calorie Surplus

Calculating Your Needs

Estimate Maintenance Calories: Use an online calculator (like the Harris-Benedict equation) to estimate your Total Daily Energy Expenditure (TDEE). This is the number of calories you need to maintain your current weight based on your age, sex, weight, height, and activity level.
Add a Moderate Surplus: For lean muscle gain, add a modest 5–10% calorie surplus to your daily intake (roughly 200–400 calories). For more rapid weight gain during an off-season, this could be slightly higher, but always monitor for excessive fat gain.

Prioritizing Nutrient Timing and Quality

Focus on Nutrient-Dense Foods: The source of your extra calories is crucial. Prioritize whole, nutrient-dense foods like fruits, vegetables, whole grains, and lean proteins rather than relying on processed, high-sugar junk foods, which can cause inflammation and impede recovery.
Optimize Macronutrients: While in a surplus, adjust your macronutrient intake to support your goals. Increase protein intake to 1.6–2.2 grams per kilogram of body weight to aid muscle repair and growth. Ensure sufficient carbohydrates are consumed to replenish glycogen stores..
Post-Workout Fueling: Consume a carb-to-protein snack within 30–60 minutes of finishing a run, especially long or intense ones, to kickstart the recovery process. Chocolate milk is a classic example that provides a good ratio.

Comparison: Calorie Maintenance vs. Strategic Surplus


Feature	Calorie Maintenance	Strategic Calorie Surplus
Primary Goal	Maintain current weight and fitness level.	Build muscle, maximize strength gains, or support high-volume training.
When to Use	Off-season, base-building, or for general fitness.	During dedicated strength training blocks or peak phases of high-volume endurance training.
Energy Source	Enough fuel to cover daily activity and running.	Excess energy for muscle repair, growth, and replenishing maximal glycogen stores.
Body Composition	Relatively stable.	Gradual increase in weight, primarily from lean mass if managed correctly.
Recovery	Adequate, but potentially slower compared to a surplus.	Optimized and accelerated, especially after intense or long workouts.
Performance Impact	Supports consistent performance without major shifts.	Aids in boosting strength and adapting to increased training demands.

Conclusion: Making the Right Choice for Your Goals

Deciding whether to eat in a calorie surplus is not a one-size-fits-all approach for runners. It is a calculated, goal-oriented nutritional strategy. A controlled surplus is highly beneficial for those focused on gaining strength, building muscle, and optimizing recovery during intense training periods or the off-season. However, if weight loss is the priority, a deficit is the correct path. The key is to be intentional with your fueling, prioritize nutrient-dense food, and monitor your body's response, adjusting as needed. By aligning your nutritional intake with your training goals, you can effectively use a calorie surplus as a tool to enhance your running performance and overall health.

Healthy Food Choices for Runners in a Surplus

Whole Grains: Oatmeal, quinoa, brown rice, whole-wheat bread.
Lean Proteins: Chicken breast, turkey, fish, eggs, tofu, lentils.
Healthy Fats: Avocado, nuts, seeds, olive oil.
Fruits and Vegetables: A wide variety to ensure adequate micronutrients and antioxidants.
Dairy (or alternatives): Greek yogurt, milk, cottage cheese for protein and calcium.
Post-Run Smoothies: Blend milk, protein powder, fruit, and nut butter for an easy way to consume calories for recovery.

For more information on nutritional strategies for runners, consider consulting resources like the marathon training guidelines from Abbott World Marathon Majors.

Frequently Asked Questions

No, a calorie surplus is not for all runners. It is best suited for those in a specific training phase, such as building muscle in the off-season or fueling extremely high-volume endurance training. For runners focused on weight loss, a calorie deficit is necessary.

For lean muscle gain, experts typically recommend a modest calorie surplus of about 200–400 calories per day, in addition to consistent strength training. Monitoring progress and adjusting intake is important to minimize excess fat gain.

During intense training, under-fueling can lead to fatigue, a drop in performance, slower recovery, and a higher risk of injury, stress fractures, and illness. It can also lead to a more serious condition known as RED-S.

No, a calorie surplus should prioritize nutrient-dense foods. Eating primarily junk food can lead to unwanted fat gain and increased inflammation, which can impair performance and overall health.

First, estimate your maintenance calories (TDEE) using an online calculator. Then, add a modest 5–10% surplus to that number. For example, if your TDEE is 2,500 calories, a 10% surplus means adding 250 calories for a total of 2,750.

While beginners might see some initial muscle gain at maintenance, a calorie surplus is the most efficient way to build muscle, especially for experienced runners. It provides the necessary energy for muscle protein synthesis.

For endurance races, it is better to err on the side of slightly over-fueling than under-fueling. A small, controlled surplus ensures you have the fuel stores needed for peak performance, whereas a deficit risks fatigue and poor race-day execution.