By Dr. Sarah Kim · Published April 4, 2025 · 8 min read
To gain muscle, most people need to eat 200–500 calories above their Total Daily Energy Expenditure (TDEE) — roughly a 10–20% surplus. The exact number depends on your body weight, training experience, and goals. Bigger is not better: a 2023 randomized controlled trial found that larger surpluses build no more muscle than moderate ones, but add significantly more body fat. This guide walks you through the full calculation so you can find your personal target.
⚠️ Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. Consult a healthcare professional or registered dietitian before making significant changes to your diet, especially if you have a medical condition.
Why Calories Matter for Muscle Growth
Muscle tissue is expensive to build. Your body needs both raw materials — amino acids from protein — and an energy signal that says conditions are right for growth. That signal is a calorie surplus: consuming slightly more energy than you burn each day.
A 2019 review in Frontiers in Nutrition confirmed that an energy surplus supports the anabolic environment needed for muscle hypertrophy during resistance training. Conversely, a 2022 meta-analysis in the Scandinavian Journal of Medicine & Science in Sports found that a deficit of roughly 500 kcal per day was enough to significantly impair lean mass gains from resistance training — even when protein intake was adequate.
The takeaway: you do not need to eat enormous amounts, but you do need to eat enough.
For a foundational understanding of how energy works in your body, see our guide on what calories actually are.
Step 1: Calculate Your TDEE
Your Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a day. It is the baseline you add your surplus to — and it is the most important number to get right.
Calculate Your BMR
Start with the Mifflin-St Jeor equation, the most validated formula for estimating Basal Metabolic Rate (BMR) — the calories your body burns at complete rest:
- Men: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) + 5
- Women: BMR = (10 × weight kg) + (6.25 × height cm) − (5 × age) − 161
Multiply by Your Activity Level
Multiply your BMR by the activity factor that best matches your typical week:
| Activity Level | Multiplier | What It Looks Like |
|---|---|---|
| Sedentary | 1.20 | Desk job, no exercise |
| Lightly active | 1.375 | Light exercise 1–3 days/week |
| Moderately active | 1.55 | Moderate exercise 3–5 days/week |
| Very active | 1.725 | Hard training 6–7 days/week |
| Extremely active | 1.90 | Intense daily training + physical job |
Example: A 30-year-old man, 80 kg, 180 cm, training 4 days per week.
- BMR = (10 × 80) + (6.25 × 180) − (5 × 30) + 5 = 1,880 kcal
- TDEE = 1,880 × 1.55 = 2,914 kcal
- Muscle-building target = 2,914 + 300 = ~3,200 kcal
For a deeper guide to calculating your daily needs, visit our how many calories should I eat article.
Step 2: Add the Right Calorie Surplus
Once you know your TDEE, choose a surplus size based on your goal and training history:
| Surplus Type | Extra Calories/Day | Weekly Weight Gain | Best For |
|---|---|---|---|
| Conservative (lean bulk) | 150–250 kcal | 0.1–0.2 kg/week | Experienced lifters, fat-sensitive goals |
| Moderate (recommended) | 250–400 kcal | 0.2–0.4 kg/week | Most people — best muscle-to-fat ratio |
| Aggressive (dirty bulk) | 500–1,000 kcal | 0.5–1.0 kg/week | Underweight beginners only |
A 2023 RCT in Sports Medicine - Open compared small (~5%) and large (~15%) energy surpluses in resistance-trained individuals over 8 weeks. Both groups gained similar muscle thickness and strength, but the large-surplus group gained significantly more body fat. Start with a moderate surplus and adjust based on your weekly weigh-in data.
Target weight gain rate: 0.25–0.5% of your body weight per week. For an 80 kg person, that is 200–400 grams per week. More than this, and you are accumulating excess fat. Less for two consecutive weeks, and it is time to add 100–150 calories.
Step 3: Set Your Macros
Calories provide the energy; macronutrients determine what your body does with it. For muscle gain, get these ratios right:
| Macro | Target Range | Example: 80 kg, 3,200 kcal |
|---|---|---|
| Protein | 1.6–2.2 g/kg body weight | 130–175 g (~600 kcal) |
| Carbohydrates | 4–7 g/kg body weight | 320–560 g (~1,500 kcal) |
| Fat | 0.5–1.5 g/kg body weight | 40–120 g (~900 kcal) |
- Protein drives muscle protein synthesis (MPS). Prioritize hitting your protein target every day before worrying about anything else. For a detailed breakdown, read our daily protein requirements guide.
- Carbohydrates fuel your training sessions and replenish glycogen for recovery. Do not cut carbs during a muscle-building phase — they are your performance fuel.
- Fat supports testosterone production and hormonal health. Never drop below 0.5 g/kg; hormonal disruption will undermine your gains.
How Training Experience Affects Your Calorie Needs
Your training history is one of the most overlooked variables in muscle-gain nutrition. The less experienced you are, the more aggressively you can gain:
| Experience Level | Training History | Realistic Muscle Gain | Recommended Surplus |
|---|---|---|---|
| Beginner | < 1 year | 0.5–1.0 kg/month | 300–500 kcal/day |
| Intermediate | 1–3 years | 0.25–0.5 kg/month | 200–400 kcal/day |
| Advanced | 3+ years | 0.1–0.25 kg/month | 100–250 kcal/day |
Beginners experience a well-documented "newbie gains" phase — they can build muscle faster than the body's normal ceiling because the neuromuscular adaptations are happening simultaneously with hypertrophy. Advanced lifters operate near their genetic potential, so a large surplus would convert almost entirely to fat rather than muscle.
Calorie Needs for Women vs. Men
Women can absolutely build significant muscle — the process is biologically identical. The differences are quantitative, not qualitative:
- Lower baseline TDEE. Women's average TDEE is typically 400–600 kcal lower than a man of similar height and weight due to differences in lean mass and hormonal profile.
- Smaller absolute surplus. Because women gain muscle at a slower absolute rate, a surplus of 150–300 kcal is usually sufficient. A 500+ calorie surplus will produce more fat than muscle for most women.
- Hormonal considerations. Estrogen supports muscle repair and reduces muscle breakdown, which is a physiological advantage. Women may also experience cyclical fluctuations in energy, performance, and weight — this is normal and does not mean the diet is failing.
ℹ️ For Women Specifically
If your goal is to gain muscle, aim for 0.15–0.25% of your body weight per week in the scale average. For a 65 kg woman, that is 100–160 grams per week — a pace that maximizes muscle gain while minimizing fat accumulation.
Can You Build Muscle in a Calorie Deficit?
Yes — but only under specific conditions. Body recomposition (simultaneously losing fat and gaining muscle) is achievable for:
- True beginners in their first 3–6 months of resistance training
- People returning after a training break of 3+ months
- Individuals with higher body fat (generally above 20% for men, 28% for women)
For everyone else — trained individuals already at a healthy body fat — true recomposition is extremely slow. If you are in this group, committing to a clear muscle-building phase at a moderate surplus will produce faster results. Once you have gained the muscle, a short cutting phase can strip the small amount of fat gained alongside it.
For more on the science of fat loss alongside muscle retention, read our guide on calories and weight loss.
What to Do If You Are Not Gaining Muscle
If you are training consistently but the scale is not moving after two or more weeks, the most common cause is a hidden calorie deficit. Frequent reasons:
- Underestimating portion sizes. Studies consistently show people underestimate their calorie intake by 20–40%. Weigh food on a kitchen scale for at least two weeks to recalibrate your eye.
- NEAT compensation. When you start eating more, some people unconsciously move less during the day — fidgeting less, walking less — which erases the surplus. Track your step count.
- Adaptive thermogenesis. Your metabolism ramps up slightly in response to a calorie surplus. If you have been in a surplus for 8+ weeks, your TDEE itself may have risen.
- Inconsistent eating on weekends. A 400-calorie surplus Mon–Fri can be erased by 500-calorie deficits on Saturday and Sunday. Weekly average matters more than any single day.
Action: Add 150–200 calories to your daily target and re-evaluate after two more weeks.
Step-by-Step Action Plan
For practical meal ideas that hit these calorie and macro targets, see our bulking meal plan.
Frequently Asked Questions
How many extra calories do I need to build muscle?
A surplus of 200–500 calories above your TDEE is sufficient for most people. The 2023 Sports Medicine - Open RCT found that larger surpluses produced similar muscle gains but significantly more fat gain compared to moderate surpluses. Start at 300 calories above TDEE and adjust based on your weekly weight trend.
Can I build muscle without eating more calories?
Yes, but mainly in specific situations — beginners, those returning after a break, or individuals with elevated body fat can build muscle near or at maintenance through body recomposition. For most trained people, a surplus is more effective. The 2022 Murphy & Koehler meta-analysis showed that even a 500 kcal daily deficit significantly impairs lean mass gains.
How many calories should a woman eat to gain muscle?
Start by calculating your TDEE using the Mifflin-St Jeor equation and add 150–300 calories. Target a weekly scale increase of 0.15–0.25% of your body weight to maximize muscle gain with minimal fat accumulation. The formula is the same as for men — the numbers are just smaller due to lower baseline TDEE.
What is the best calorie surplus for lean bulking?
A conservative surplus of 200–350 calories is the sweet spot for most intermediate and advanced lifters. It produces near-identical muscle gains to larger surpluses while keeping fat gain minimal, meaning a much shorter and easier cut afterward.
How long until I see results from eating more to gain muscle?
Strength improvements can appear within 2–4 weeks. Visible muscle changes typically take 8–12 weeks of consistent training and eating. The scale will start to reflect the surplus within 1–2 weeks once glycogen stores are fully replenished.
Track Your Muscle-Building Nutrition
Knowing your calorie target is step one. Consistently hitting it — especially your protein goal — is what drives actual results. Tracking does not have to mean weighing every gram. Caloria, the AI calorie tracker, estimates calories and macros from a single photo of your meal, so you can stay on target without the friction of manual entry.
Download Caloria and see exactly what you are eating: