If you're trying to eat to gain muscle, your diet's job is straightforward: fuel your training and supply the building blocks your body uses to repair and build muscle afterward. Over time, the combination of a well-structured training program and a solid nutrition strategy can lead to amazing adaptations both in strength and muscle growth.

"Think of your workout as the challenge and nutrition as the support crew," says Brenna Larson, RDN, a dietitian on Factor's nutrition team. "Protein helps repair and build muscle, carbohydrates fuel your workouts, and a variety of nutrient rich foods provide the vitamins and minerals your body needs to recover and come back stronger.”

This guide covers exactly how to eat to build muscle, and the myths holding you back from reaching your gains goals through good nutrition.

Match Your Caloric Intake to Your Goal

Before you adjust a single macro, your total energy intake sets the ceiling for what your training can produce. Calories are the measurement unit we use to describe energy expenditure and intake. Simply put, calories = energy.

Getting energy intake right depends on energy balance, a state in which the amount of energy consumed is equal to the amount of energy expended. In this state you can expect to maintain your weight and have sufficient energy to get through all your daily activities.

Do You Need to Eat in a Calorie Surplus to Build Muscle?

Factors such as age, body fat percentage, and speed of the metabolism will dictate if someone can build muscle by eating at maintenance calories or if a modest surplus is needed. It’ll differ from person to person. A 2019 review in Frontiers in Nutrition¹ found that an energy surplus is not strictly required for muscle growth.

Newer lifters and those carrying more body fat can often gain muscle while eating at or near maintenance. Leaner, more experienced lifters who have already captured the easy progress may benefit from a modest surplus. A large surplus tends to add more body fat than muscle, so bigger is not better here.

You don’t need a lab to know whether you’re eating enough calories to build muscle. Is your training progressing over time, with more reps, weight, or better-quality sessions? Is your day-to-day energy holding up? And is your weight steady or climbing slowly? If you can answer yes to those questions, your intake is likely in the right place.

Make Protein the Priority

Your muscle tissue is in a constant state of turnover, breaking down and rebuilding throughout the day. Resistance training increases the demand for protein because it ramps up the rebuilding side of that equation. The International Society of Sports Nutrition⁴ notes that resistance exercise and protein intake work together to stimulate muscle protein synthesis, the process that turns the food you eat into new muscle.

So how much do you actually need?

Daily Protein: Aim for 1.6 to 2.2 Grams per Kilogram of Bodyweight

A daily intake of roughly 1.6 to 2.2 grams of protein per kilogram of body weight supports muscle growth and recovery for most adults participating in resistance training, according to a widely cited meta-analysis in the British Journal of Sports Medicine⁵.

If you weigh 80 kilograms, which is about 176 pounds, that puts your daily target somewhere around 128 to 176 grams of protein.

Per-Meal Protein: About 0.4 Grams per Kilogram, Spread Across the Day

Hitting your daily total matters more than any single meal, though how you distribute protein still helps. Research by Schoenfeld and Aragon⁶ supports eating about 0.4 grams of protein per kilogram of body weight per meal across at least four meals. That spread helps you reach your daily total and keeps a steady supply of protein available for your muscles to build with.

High-quality proteins such as dairy, eggs, meat, soy, and whey naturally provide leucine, an amino acid that plays an important role in stimulating muscle protein synthesis. A 2025 review on protein for athletes⁷ notes that a mix of animal and plant proteins can support muscle growth, as long as your total intake and overall protein quality are adequate.

Total daily protein is the number that has the greatest impact. Distribution and per-meal targets are useful refinements once your daily total is consistent, so do not let perfect meal spacing distract you from simply eating enough across the day.

Fuel Training With Carbohydrates

Carbohydrates are your body's preferred fuel for the hard, repeated efforts that strength training demands. Your muscles store carbohydrate as glycogen, and that glycogen powers high-intensity sets. An ISSN position on nutrient timing⁸ explains how resistance exercise draws on these glycogen stores, which is part of why under-fueling on carbohydrates can leave your sessions feeling flat.

How many carbohydrates you need scales with how much and how hard you train. The Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine outlines general carbohydrate ranges by training load in their joint position stand⁹:

• ~3 to 5 grams per kilogram of body weight per day for light activity
• 5 to 7 grams for moderate training of about an hour a day, and 6 to 10 grams for longer, higher-intensity endurance work.

The higher ranges apply mainly to high-volume or endurance-heavy schedules, so you likely do not need to eat like a marathoner to support your lifting. These recommendations are intended as general starting points and should be adjusted based on total training volume, goals, and body size.

Add Dietary Fat in Moderation

Fat gets less attention in conversations about muscle building, but it’s still an important nutrient for overall health and vitality. Dietary fat helps your body produce hormones and absorb the fat-soluble vitamins A, D, E, and K. Cutting it too low can work against you: a 2025 meta-analysis in the Journal of Steroid Biochemistry and Molecular Biology¹⁰ found that very low-fat diets are linked to modestly reducing testosterone concentrations in some men, although overall energy intake appears to play a larger role than dietary fat alone.

A 2020 review of nutrition for physique athletes¹¹ points out that the link between fat intake and testosterone is likely driven more by overall energy availability than by fat itself, and recommends fat in the range of 20 to 35 percent of total calories for people who train regularly.

Do You Need to Time Meals Around Training?

This is where a lot of energy gets misdirected. The idea of a narrow post-workout window, where you must get protein within 30 minutes or lose your gains, is not legitimate. A 2025 systematic review and meta-analysis in Nutrients¹² found that the timing of protein around training makes little difference to gains in muscle or strength once total daily intake is accounted for. Your total protein and energy across the day do the heavy lifting.

The same nutrient-timing guidance suggests spacing protein across the day, roughly every three to four hours, to keep muscle protein synthesis active. A light, easily digested snack with some carbohydrate and protein about an hour before training can help you feel fueled, while a heavier meal too close to a session may make things uncomfortable. After training, aim to eat a normal balanced meal within a couple of hours.

For most strength sessions, you don’t need to eat anything during the workout. For long or very demanding sessions beyond an hour, something easily digested like a sports drink (with sugar) or a banana can help sustain your output.

Hydrate to Protect Performance

Hydration plays a critical role in strength training by supporting performance, recovery, and overall health. Water is essential for regulating body temperature, transporting nutrients, and maintaining joint and muscle function. Even mild dehydration can negatively impact strength, endurance, and focus during training sessions.

A 2025 review of hydration biomarkers¹³ reports that a body-mass loss of 3 to 4 percent from dehydration can reduce muscular strength by around 2 percent and power by around 3 percent. The effect shows up at lower levels too: A 2025 trial in Nutrients¹⁴ found that a 2 percent reduction in body mass through dehydration significantly lowered jump height, power output, and knee strength in trained athletes.

You do not need to track every ounce. Drink fluids steadily across the day, keep water available during your sessions, and use simple signals to gauge where you stand. Pale yellow urine generally points to good hydration, while dark urine, lingering fatigue, headaches, or a dip in training performance can mean you need more.

For longer or hotter sessions where you sweat heavily, you can replace fluids along with electrolytes like sodium and potassium, which plain water alone will not fully restore.

Common Myths About Nutrition for Strength Training

Myth: You can only use 20 to 30 grams of protein per meal

Dietitian reality: Your body can digest and use far more than that. The practical per-meal target for maximizing muscle signaling is around 0.4 grams per kilogram, and protein beyond that is still put to use for other functions rather than wasted. Your daily total is what counts most.

Myth: You have to eat protein within 30 minutes of training

Dietitian reality: The anabolic window is far wider than the old advice implied. Once your daily protein and energy are adequate, the exact timing around your workout makes little difference to muscle or strength gains.

Myth: You need a big calorie surplus to build muscle

Dietitian reality: A large calorie surplus tends to increase body fat more than muscle. Newer lifters and those with higher body fat can often build muscle at or near maintenance, while experienced lifters typically do well with only a modest surplus.

Myth: More protein always means more muscle

Dietitian reality: The benefit levels off around 1.6 grams per kilogram per day for most people. Eating well above that will not buy you extra muscle, though slightly higher intakes help when you are dieting to lose fat.

Myth: Carbohydrates are unnecessary for lifting

Dietitian reality: Carbohydrates refill the glycogen that fuels high-intensity sets and help spare protein for its main job of building muscle. Cutting carbohydrates too low can have an adverse affect on your training and results.

Putting It All Together: 4 Tips for Muscle-Building Nutrition

Knowing the separate principles is one thing. Here is how they come together day to day.

1. Build Each Plate Around Protein

Start each meal with a protein source and a target of roughly 25 to 40 grams, then add quality carbohydrates sized to your training and a portion of healthy fat. This structure makes your daily protein and energy targets far easier to reach without much tracking.

2. Spread Your Intake Through the Day

Aim for three to five eating occasions with protein at each, roughly every three to four hours. Find the meal frequency that fits your schedule and appetite, since the best pattern is the one you can repeat consistently.

3. Fuel and Refuel Around Training

Eat a balanced meal a few hours before training, or a lighter carbohydrate-and-protein snack if your session is closer. Afterward, have a normal meal within a couple of hours, and keep water on hand throughout.

4. Adjust for Your Goal

If you are gaining, nudge calories up slowly and watch your weekly weight trend. If you are leaning out, hold protein high to protect muscle while you pull calories from elsewhere. Reassess every few weeks based on your weight trend and how your training is progressing.

When You'd Rather Have Factor Meal Prep For You

Hitting a protein target at every meal and fueling correctly around training takes planning and cooking that not everyone has time for. Factor’s Fitness meal delivery brings you chef-crafted, dietitian-designed meals with the macros listed on every label, ready to heat and eat in a few minutes. For someone training hard, that means hitting your protein and energy targets without the daily prep, with the numbers behind each meal already in front of you.

Dietitian's picks:

• Mediterranean Grilled Chicken with Chickpea Mash and Lemon Rice: Pairs protein with quality carbohydrate to refuel glycogen after training.
• Protein Shake Variety Pack Bundle: An easy way to add protein between meals or after a session when you’re short on time.
• Factor Form Hydration Boost Variety Pack: Supports hydration and electrolyte replacement around longer or hotter training sessions.

References

[1] https://www.frontiersin.org/articles/10.3389/fnut.2019.00131/full

[2] https://reference.medscape.com/calculator/846/mifflin-st-jeor-equation-calculator

[3] https://www.omnicalculator.com/health/bmr-harris-benedict-equation

[4] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5477153/

[5] https://bjsm.bmj.com/content/52/6/376

[6] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5828430/

[7] https://pmc.ncbi.nlm.nih.gov/articles/PMC12655512/

[8] https://pmc.ncbi.nlm.nih.gov/articles/PMC5596471/

[9] https://pubmed.ncbi.nlm.nih.gov/26920240/

[10] https://www.sciencedirect.com/science/article/abs/pii/S0960076021000716

[11] https://pmc.ncbi.nlm.nih.gov/articles/PMC7052702/

[12] https://pmc.ncbi.nlm.nih.gov/articles/PMC12250900/

[13] https://www.mdpi.com/2072-6643/17/9/1452

[14] https://www.mdpi.com/2072-6643/17/9/1452