How Many Calories Should I Eat in a Day to Gain Muscle?

According to a 2019 review, consuming a calorie surplus of approximately 350 to 500 calories per day, alongside regular resistance training, is beneficial for muscle gain. Understanding precisely how many calories you should eat in a day to gain muscle is the critical first step to a successful bulking phase.

Quick Summary

This guide provides a detailed breakdown of how to calculate your individual calorie surplus for muscle gain, covering the importance of a modest surplus, ideal macronutrient ratios, and how to adjust your intake based on progress. It demystifies the process of fueling muscle growth while minimizing excess fat.

Key Points

• Start with a modest calorie surplus: Aim for 250-500 calories above your Total Daily Energy Expenditure (TDEE) to maximize muscle gain and minimize excess fat accumulation.

• Calculate your TDEE: Use established formulas like the Mifflin-St. Jeor equation and an activity multiplier to determine your maintenance calories accurately.

• Prioritize protein intake: Ensure you consume 1.6 to 2.2 grams of protein per kilogram of body weight to support muscle repair and growth.

• Balance your macronutrients: After setting protein, allocate the remaining calories to carbohydrates (45-65%) for energy and healthy fats (20-35%) for hormonal function.

• Monitor and adjust: Regularly track your weight, body composition, and strength gains, adjusting your caloric intake every 2-4 weeks to match your body's changing needs.

• Focus on clean bulking: Prioritize nutrient-dense, whole foods over processed, high-calorie junk food to ensure healthy, sustainable muscle growth.

Why a Calorie Surplus is Non-Negotiable for Muscle Growth

Building muscle, or hypertrophy, is an energy-intensive process that requires more fuel than your body needs for maintenance. This intentional overconsumption is known as a calorie surplus, and it is the fundamental nutritional requirement for adding lean mass. When you engage in resistance training, you create microscopic tears in your muscle fibers. A calorie surplus provides the necessary energy and building blocks (specifically, protein) to repair these tears, making the fibers stronger and larger than before. Eating at or below maintenance calories, also known as a caloric deficit, forces the body to prioritize other functions and can even lead to muscle loss. A modest surplus is the most effective approach to fuel growth while minimizing undesirable fat gain.

How to Calculate Your Calorie Needs

Your calorie goal is not a fixed number; it depends on your Total Daily Energy Expenditure (TDEE), which is determined by several factors, including your basal metabolic rate (BMR), physical activity level, age, sex, weight, and height.

1. Estimate Your BMR: The Mifflin-St. Jeor equation is a widely used method for this calculation.

   • Men: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5
   • Women: BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161

2. Determine Your TDEE: Multiply your BMR by an activity factor that corresponds to your exercise level.

   • Sedentary: BMR × 1.2
   • Lightly Active (1-3 days/week): BMR × 1.375
   • Moderately Active (3-5 days/week): BMR × 1.55
   • Very Active (6-7 days/week): BMR × 1.725
   • Extra Active (Daily/physical job): BMR × 1.9

3. Add Your Surplus: To gain muscle, add a modest surplus of 250 to 500 calories to your TDEE. A more conservative approach of 250 calories is recommended for beginners to minimize fat gain, while experienced trainees might aim for the higher end.

The Critical Role of Macronutrients

While total calories are important, the composition of those calories—your macronutrient ratio—is what dictates the quality of your gains. A well-balanced diet is essential for fueling workouts, repairing tissue, and supporting overall health.

• Protein: Crucial for muscle repair and growth. A high intake of 1.6 to 2.2 grams of protein per kilogram of body weight is often recommended.
• Carbohydrates: Your body's primary energy source. They replenish muscle glycogen stores, fueling intense training sessions. Aim for 45–65% of your total calories from carbohydrates.
• Fats: Essential for hormone production and vitamin absorption. They also provide a dense energy source. Healthy fats should make up 20–35% of your daily calories.

Clean Bulking vs. Dirty Bulking: A Comparison

Choosing the right approach to your calorie surplus is key to achieving your desired physique. The primary difference lies in the source of your additional calories.

Feature	Clean Bulking	Dirty Bulking
Calorie Source	Primarily nutrient-dense, whole foods (lean proteins, complex carbs, healthy fats).	High-calorie, often processed and sugar-laden foods (fast food, sweets, fried items).
Rate of Gain	Gradual, controlled weight gain with a focus on lean muscle mass.	Rapid weight gain, often resulting in significant fat accumulation.
Body Composition	Leads to high-quality muscle gains with minimal fat. Easier to cut later.	Causes a large increase in body fat percentage, which can negatively impact health and requires a more intense cutting phase.
Health Impact	Supports overall health, energy levels, and nutrient intake.	Can cause poor health markers, inflammation, and energy crashes.

Adjusting and Monitoring Progress

Your nutritional needs are not static. As you gain muscle and weight, your body's energy requirements increase, necessitating adjustments to your calorie and macronutrient intake. Track your progress every 2-4 weeks by monitoring your body weight, physique changes through photos, and strength progression in your workouts.

• If your progress stalls: Increase your daily calories by a small increment, such as 100-200 calories, to reignite growth.
• If you are gaining fat too quickly: A modest fat gain is normal, but if it is excessive, slightly decrease your calorie surplus.

For more detailed information on monitoring body composition, resources such as the National Institutes of Health provide in-depth scientific reviews on the effects of different macronutrient intakes and bulking methods.

Conclusion

Understanding how many calories you should eat in a day to gain muscle is a strategic process, not a simple target number. By calculating your TDEE and applying a modest calorie surplus of 250–500 calories from nutrient-dense foods, you provide your body with the necessary energy to fuel muscle growth effectively. Prioritizing protein intake and balancing carbohydrates and healthy fats ensures you are building quality lean mass, not just gaining weight. Consistent monitoring and adjustments based on your body's response are essential for a successful and healthy bulking phase.

Frequently Asked Questions

Is it possible to gain muscle and lose fat at the same time?

Yes, but it is much more achievable for beginners or those with higher body fat percentages. It is a challenging process for experienced lifters. The general approach for intermediates is to focus on one goal at a time through 'bulking' (calorie surplus for muscle gain) and 'cutting' (calorie deficit for fat loss) cycles.

What is the difference between TDEE and BMR?

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at rest to perform basic functions. Your Total Daily Energy Expenditure (TDEE) is your BMR plus the calories you burn from all daily physical activity, including exercise.

How do I know if I'm in a calorie surplus?

You can confirm you are in a calorie surplus by tracking your weight over time. A healthy rate of muscle gain is about 0.5 kilograms (around 1 pound) per week for men and slightly less for women. If your weight is increasing at this rate, your surplus is likely appropriate.

Can I gain muscle without a calorie surplus?

For most individuals, particularly experienced lifters, a calorie surplus is essential for optimal muscle gain. While beginners might see some initial muscle growth in a deficit, it is not sustainable, and eating too little will hinder progress.

Should I change my calorie target as I gain weight?

Yes, as you gain weight and muscle mass, your body's metabolic rate increases. You should reassess and adjust your calorie target every 2-4 weeks to ensure you maintain an effective surplus and continue to see results.

What happens if I eat too many calories when trying to gain muscle?

Eating too many calories will cause you to gain excessive body fat alongside muscle. A small amount of fat gain is normal during a bulking phase, but a well-controlled surplus prevents this from becoming disproportionate.

How important are carbs and fats for muscle gain?

Carbohydrates are the body's primary energy source, essential for fueling intense workouts and replenishing muscle glycogen stores. Fats are crucial for hormone production and nutrient absorption. Both are vital for a successful muscle-building diet alongside protein.