To gain muscle, you need to eat roughly 10 to 20 percent more calories than your body burns each day. For most people, that works out to an extra 350 to 500 calories above your maintenance level. This surplus gives your body the raw energy it needs to build new tissue while keeping fat gain reasonable.
The exact number varies based on your size, activity level, and training experience, but the formula is straightforward: find your maintenance calories, add a moderate surplus, and adjust based on what actually happens to your body over the following weeks.
Finding Your Maintenance Calories
Your maintenance calories, sometimes called your total daily energy expenditure, represent how much energy your body uses in a day to keep you alive, digest food, and fuel your movement. Muscle mass has a significant influence on this number, which means two people at the same weight can have very different calorie needs depending on their body composition.
The simplest starting estimate is to multiply your body weight in pounds by 14 to 17, depending on how active you are. Someone who weighs 170 pounds and trains four days a week might land around 2,550 to 2,720 calories per day as a maintenance estimate. More formal equations exist, like the Mifflin-St Jeor formula, which research shows is reasonably accurate for most people. The World Health Organization equation edges it out slightly in precision, but the differences are small enough that any well-known calculator will get you in the right ballpark.
The key is treating any formula as a starting point, not a verdict. Track your weight for two weeks while eating at your estimated maintenance. If your weight stays stable, you’ve found your number. If it drifts up or down, adjust by 200 to 300 calories and reassess.
How Big Your Surplus Should Be
A review published in the journal Sports Medicine recommends a conservative surplus in the range of roughly 360 to 480 calories per day (1,500 to 2,000 kilojoules) to maximize muscle growth while limiting unnecessary fat gain. That aligns closely with the commonly cited 10 to 20 percent above maintenance.
There is no single proven energy cost for building a kilogram of muscle. The biology is complex: your body spends calories not just on assembling new tissue but also on the increased training demands, recovery, and the metabolic overhead of carrying more mass. Because researchers haven’t pinpointed an exact figure, a moderate surplus is the safest bet. Going too far above 500 extra calories per day rarely speeds up muscle growth. It just accelerates fat storage.
If your maintenance sits around 2,500 calories, a muscle-building target of 2,850 to 3,000 calories per day is a solid range. Leaner individuals or those newer to lifting can often push closer to the 20 percent mark without excessive fat gain. If you’ve been training for years, staying closer to 10 percent makes more sense since your rate of muscle growth is slower.
Training Experience Changes the Math
Beginners have the biggest window for muscle growth. While initial strength gains in the first month come mostly from your nervous system learning the movements, noticeable muscle development follows quickly in the first year of consistent training. During this window, a surplus of 300 to 500 calories per day supports rapid gains without much wasted energy.
Advanced trainees face a very different reality. After several years of serious resistance training, even the best natural lifters may only add a few pounds of muscle per year. At that rate, a large surplus just becomes stored fat. Experienced lifters typically benefit from staying at the lower end, around 200 to 300 extra calories per day, and relying on precise tracking and regular body composition check-ins to ensure the scale is moving in the right direction.
Protein: The Most Important Macronutrient
Calories create the conditions for growth, but protein provides the building blocks. A meta-analysis covering dozens of studies found that adults under 65 doing resistance training gained the most lean body mass at 1.6 grams of protein per kilogram of body weight per day or higher. For a 170-pound (77 kg) person, that’s at least 123 grams of protein daily. Many practitioners aim for 1.8 to 2.2 grams per kilogram to leave a comfortable margin.
Spreading protein across three to five meals helps keep muscle-building processes elevated throughout the day. Each meal should contain roughly 20 to 40 grams. Prioritizing protein at meals close to your training window is helpful, though total daily intake matters far more than precise timing.
Carbohydrates and Fats Fill the Rest
Once protein is set, carbohydrates and fats divide the remaining calories. Carbohydrates are the primary fuel for resistance training, and recommendations for strength athletes range from 4 to 7 grams per kilogram of body weight per day. For the same 170-pound person, that translates to roughly 310 to 540 grams of carbs. If you’re doing high-volume training with 11 or more sets per muscle group in a session, your carbohydrate needs sit at the higher end of that range to replenish glycogen stores between workouts.
A practical guideline from the research: consuming at least 15 grams of carbohydrates along with about 0.3 grams of protein per kilogram of body weight within three hours of training supports recovery. On days with two training sessions targeting the same muscles, higher carbohydrate intake becomes especially important.
Fat should make up at least 20 to 30 percent of your total calories. Fat plays a critical role in hormone production, including testosterone and other signaling molecules involved in muscle growth. Dropping below this range consistently can compromise recovery and energy levels. For someone eating 3,000 calories, that means 67 to 100 grams of fat per day.
A Practical Setup for a 170-Pound Lifter
Here’s what the numbers look like in practice for someone weighing 170 pounds, training four to five days a week, with a maintenance of roughly 2,600 calories:
- Target calories: 2,900 to 3,100 per day (roughly 300 to 500 above maintenance)
- Protein: 130 to 170 grams (1.7 to 2.2 g/kg)
- Carbohydrates: 350 to 450 grams (4.5 to 5.8 g/kg)
- Fat: 70 to 95 grams (roughly 25 percent of total calories)
These ranges leave room for personal preference. Some people thrive on higher carbs and lower fat, others prefer a more even split. As long as protein stays high and your surplus is controlled, the carb-to-fat ratio is flexible.
Tracking Progress and Adjusting
Weigh yourself at the same time each day, ideally first thing in the morning, and use a weekly average to smooth out daily fluctuations from water, sodium, and food volume. A gain of 0.5 to 1 pound per week is a reasonable target for beginners. Intermediate and advanced lifters should expect closer to 0.5 pounds per week or less.
If your weight isn’t moving after two to three weeks, add 150 to 200 calories. If you’re gaining faster than expected, especially if your waistline is growing noticeably, pull back by the same amount. Regular body composition assessments, whether through progress photos, waist measurements, or skin-fold calipers, give you better data than the scale alone. Strength trends in the gym are another reliable signal: if your lifts are consistently progressing, your surplus is likely doing its job.
Muscle building is a slow process. Expecting visible changes over weeks rather than days keeps you from overcorrecting your calories too early. Give each adjustment at least two to three weeks before deciding whether it’s working.