To gain muscle, you need to eat roughly 10 to 20% more calories than your body burns each day. For most people, that works out to an extra 200 to 500 calories above your maintenance level, depending on your size and how active you are. This caloric surplus gives your body the raw energy it needs to build new tissue, but the size of that surplus matters more than most people realize.
Finding Your Maintenance Calories
Before you can calculate a surplus, you need to know your baseline: the number of calories your body burns in a normal day just to maintain your current weight. This includes everything from breathing and digestion to walking around and exercising. The simplest way to estimate it is to multiply your body weight in pounds by 14 to 16. Someone who weighs 170 pounds and is moderately active, for example, would land somewhere around 2,380 to 2,720 calories per day.
Online calculators that factor in your age, height, sex, and activity level can get you closer, but any formula is still just a starting point. The real test is tracking your weight over two to three weeks while eating a consistent number of calories. If your weight stays stable, you’ve found your maintenance number.
How Big Your Surplus Should Be
A surplus of 10 to 20% above maintenance is the range supported by current sports nutrition research. The goal is to gain about 0.25 to 0.5% of your body weight per week. For a 170-pound person, that means gaining roughly half a pound to just under a pound per week. Gaining faster than that doesn’t speed up muscle growth; it just adds more body fat.
Your training experience changes the equation significantly. Beginners can build muscle faster because their bodies respond more dramatically to a new stimulus, so they can handle a surplus closer to the 20% end without excessive fat gain. If you’ve been lifting consistently for several years, your rate of muscle growth slows considerably, and a smaller surplus of around 5 to 10% is more appropriate. Advanced lifters who eat in a large surplus mostly just gain fat, since their muscles have less room to grow quickly. Research on resistance-trained individuals specifically recommends scaling the surplus to experience level, with more advanced trainees gaining weight more slowly.
Realistic Muscle Gain Expectations
Most people can expect to gain roughly one to two pounds of lean muscle per month during the early stages of training with proper nutrition. Over time, that rate drops, and a half-pound of muscle per month becomes more realistic for experienced lifters. A dramatic 20- to 30-pound gain over a year is possible in total body weight, but that includes water, stored carbohydrates, and some fat alongside actual muscle tissue.
These numbers matter because they help you calibrate your expectations. If the scale is climbing three or four pounds per week, you’re eating too much and storing the excess as fat. If it’s not moving at all, your surplus isn’t large enough or you’re not training hard enough to trigger growth.
How Much Protein You Actually Need
Calories create the conditions for growth, but protein provides the building blocks. The most well-supported target is about 1.6 grams of protein per kilogram of body weight per day, with potential benefits up to 2.2 grams per kilogram. For a 170-pound (77 kg) person, that translates to roughly 123 to 170 grams of protein daily.
How you distribute that protein throughout the day also matters. About 20 to 30 grams of high-quality protein per meal is enough to maximally stimulate the muscle-building process in younger adults. Spreading your intake across four to five meals, roughly three hours apart, keeps that process elevated throughout the day rather than dumping all your protein into one or two large meals. Older adults need a higher dose per meal, closer to 40 grams, to achieve the same muscle-building response.
Splitting the Rest of Your Calories
Once protein is accounted for, the remaining calories come from carbohydrates and fats. Research on athletes focused on building muscle suggests carbohydrates should make up about 55 to 60% of total calories, with fats at 15 to 20%. That said, the International Society of Sports Nutrition notes that a wide range of dietary approaches, from lower fat to lower carb, can produce similar improvements in body composition as long as protein and total calories are on target.
Carbohydrates do play a specific role worth noting: they fuel intense training. If your workouts feel sluggish and your strength is stalling, low carbohydrate intake is often the culprit. Prioritizing carbs around your training sessions, both before and after, helps maintain the workout intensity that drives muscle growth in the first place. Fats, meanwhile, support hormone production and overall health, so dropping them below about 15% of total calories is not advisable.
Putting the Numbers Together
Here’s what a practical plan looks like for a 170-pound person with moderate training experience:
- Maintenance calories: roughly 2,550 (using a multiplier of 15)
- Surplus target: 10 to 15%, adding 255 to 380 calories
- Total daily intake: approximately 2,800 to 2,930 calories
- Protein: 130 to 170 grams per day
- Carbohydrates: 350 to 400 grams per day
- Fats: 55 to 70 grams per day
These numbers are a starting framework, not a prescription. Track your weight weekly, averaging the daily readings to smooth out normal fluctuations from water and food volume. If you’re gaining 0.25 to 0.5% of your body weight per week, you’re in the right range. If you’re gaining faster, reduce your surplus by 100 to 200 calories. If the scale isn’t moving after two to three weeks, add a similar amount.
Why a Moderate Surplus Beats a Large One
The instinct to eat as much as possible to “bulk up” is one of the most common mistakes in muscle building. Your body can only synthesize a limited amount of muscle tissue per day, no matter how many calories you throw at it. Every calorie beyond what your body can use for muscle repair and growth gets stored as fat. A study on resistance-trained individuals found a strong relationship between the rate of weight gain and increases in skinfold thickness, meaning faster weight gain reliably predicted more fat accumulation rather than more muscle.
Gaining excess fat also means you’ll eventually need to diet it off, which risks losing some of the muscle you just built. A controlled surplus keeps you in a productive range where muscle is being built without creating a lengthy fat-loss phase afterward. The patience to gain slowly is, counterintuitively, the fastest path to looking more muscular.