For anyone committed to a resistance training program with the goal of building muscle, the single most important nutritional factor is consuming a calorie surplus. This means consistently eating more calories than your body burns each day, providing the necessary energy to fuel intense workouts and, more critically, to power the complex biological process of muscle protein synthesis—the creation of new muscle tissue. Without this extra energy, your body simply cannot prioritize building new, metabolically expensive tissue, regardless of how hard you train. This principle applies to all individuals, from novice lifters to seasoned athletes, who are seeking to maximize their potential for muscular hypertrophy, or growth.
Understanding Energy Balance and Muscle Growth
At its core, your body weight is governed by a simple principle: energy balance. This is the relationship between the calories you consume (energy in) and the calories you expend (energy out). When you eat fewer calories than you burn, you are in a calorie deficit, and your body breaks down stored tissue (both fat and muscle) for energy, leading to weight loss. When you eat the same number of calories you burn, you are at maintenance, and your weight remains stable.
To build muscle, a process known as anabolism, your body needs to be in a state where it has more than enough resources to meet its daily energy demands. Building muscle is an energy-intensive process. Think of it like constructing a new building. You not only need the raw materials (protein) but also a significant amount of energy to power the machinery and pay the workers who assemble those materials. A calorie surplus provides that essential energy.
When you don’t provide this surplus, your body remains in a state focused on survival and homeostasis. It will use the calories you eat to fuel your brain, keep your heart beating, and power your daily movements. Building new muscle is a luxury it can’t afford without extra fuel in the tank. This is why individuals who train hard but fail to eat enough often experience a frustrating plateau, where they feel stronger but don’t see the physical size gains they expect.
Calculating Your Calorie Target for a Surplus
Determining the right number of calories can feel daunting, but it can be broken down into a logical, step-by-step process. The goal is to find your maintenance level and then add a modest surplus to encourage muscle growth while minimizing fat gain.
Step 1: Estimate Your Basal Metabolic Rate (BMR)
Your BMR is the number of calories your body burns at complete rest to perform its most basic, life-sustaining functions. It accounts for the majority of your daily calorie expenditure. While a lab test is the most accurate way to measure it, you can get a reliable estimate using formulas like the Mifflin-St Jeor equation, which is widely considered one of the most accurate.
For men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
For women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
Step 2: Determine Your Total Daily Energy Expenditure (TDEE)
Your TDEE is your BMR plus the calories you burn from all other activities, including exercise and daily movement. To find your TDEE, you multiply your BMR by an activity factor that best represents your lifestyle.
- Sedentary (little to no exercise): BMR × 1.2
- Lightly Active (light exercise/sports 1-3 days/week): BMR × 1.375
- Moderately Active (moderate exercise/sports 3-5 days/week): BMR × 1.55
- Very Active (hard exercise/sports 6-7 days a week): BMR × 1.725
- Extra Active (very hard exercise & a physical job): BMR × 1.9
The resulting number is your estimated maintenance calories—the amount you need to eat to keep your weight stable.
Step 3: Create a Modest Surplus
Once you know your TDEE, the final step is to add calories to create your surplus. A common mistake is to add too many calories too quickly, which leads to excessive and unnecessary fat gain. A slow and controlled approach is far more effective for building primarily lean mass.
A sensible and effective surplus is typically between 250 to 500 calories above your TDEE. For example, if your calculated TDEE is 2,500 calories, your target intake for building muscle would be between 2,750 and 3,000 calories per day. This small surplus provides enough extra energy for muscle synthesis without overwhelming your body’s ability to build lean tissue, which would cause the excess to be stored as fat.
What to Eat: The Quality of Your Calories Matters
Simply hitting a calorie number isn’t enough. The composition of those calories—your macronutrients—is just as important. A diet filled with processed, low-nutrient foods will not support optimal health or muscle growth, even if it meets your calorie target. This is often called a “dirty bulk.” A “clean bulk,” focused on whole, nutrient-dense foods, is the superior strategy.
Protein: The Building Blocks
Protein is the most critical macronutrient for muscle growth. Resistance training creates microscopic tears in your muscle fibers, and dietary protein provides the amino acids needed to repair that damage and rebuild the fibers bigger and stronger. Without sufficient protein, your body cannot complete this repair process effectively.
For active individuals looking to build muscle, a protein intake of 1.6 to 2.2 grams per kilogram of body weight (or about 0.7 to 1.0 grams per pound) is the evidence-based recommendation. Prioritize high-quality protein sources like lean meats, poultry, fish, eggs, Greek yogurt, cottage cheese, and high-quality protein powders. Plant-based athletes can rely on tofu, tempeh, edamame, lentils, and beans.
Carbohydrates: The Fuel for Performance
Carbohydrates are your body’s primary and preferred source of energy. They are broken down into glucose, which fuels your workouts and allows you to train with the intensity needed to stimulate muscle growth. Carbs are also stored in your muscles and liver as glycogen, which is crucial for performance and recovery.
Cutting carbs too low while trying to build muscle is a counterproductive strategy. Focus on complex carbohydrates that provide sustained energy, such as oats, brown rice, quinoa, sweet potatoes, and whole-grain bread. Fruits and vegetables are also excellent sources of carbs, vitamins, and minerals.
Fats: The Engine for Hormones and Health
Dietary fats are essential for overall health and play a vital role in producing key hormones, including testosterone, which is directly involved in muscle regulation. Healthy fats also help with the absorption of fat-soluble vitamins and reduce inflammation.
Ensure you are consuming enough healthy fats from sources like avocados, nuts, seeds, olive oil, and fatty fish like salmon. A general guideline is to have fats comprise 20-30% of your total daily calories.
Putting It All Together: Consistency and Adjustment
Once you have your calorie and macronutrient targets, the key to success is consistency. Hitting your numbers day in and day out is what drives progress. This requires planning, meal preparation, and tracking your intake, at least in the beginning, to ensure you are on the right path.
It’s also crucial to monitor your progress and be willing to adjust. Weigh yourself 2-3 times per week under the same conditions (e.g., first thing in the morning) and take a weekly average. A healthy rate of weight gain for building lean mass is approximately 0.25% to 0.5% of your body weight per week. If you are gaining faster than this, you are likely accumulating too much body fat and should slightly reduce your calories. If you are not gaining weight, you are not in a true surplus and need to incrementally increase your calories.
Remember, a calorie surplus does not work in a vacuum. It must be paired with a well-structured, progressive resistance training program. The training provides the stimulus for growth, and the nutrition provides the resources to make that growth happen. One cannot be effective without the other.
In conclusion, eating enough is not just a suggestion for building muscle; it is a fundamental requirement. By calculating your TDEE, establishing a modest calorie surplus of 250-500 calories, and focusing on nutrient-dense sources of protein, carbohydrates, and fats, you create the ideal anabolic environment for your body to build new muscle tissue. This deliberate and patient approach, combined with consistent and challenging training, is the most reliable path to achieving your strength and physique goals.
