Macros for Muscle Gain: How to Calculate Your Bulking Macros

Building muscle requires two things: progressive resistance training and the right nutrition. You can train as hard as you want, but without enough calories and protein, your body won't have the raw materials to build new muscle tissue.

This guide covers exactly how to set your calories and macros for muscle gain — how much of a surplus you actually need, how to distribute protein, carbs, and fat, and what realistic muscle gain looks like. Every recommendation is backed by peer-reviewed research.

How Big Should Your Calorie Surplus Be?

You need a calorie surplus to build muscle efficiently — but bigger is not better. Research consistently shows that large surpluses primarily add fat, not extra muscle.

A 2023 study by Helms et al. in Sports Medicine – Open randomized trained lifters into maintenance, moderate surplus (+5%), or high surplus (+15%) groups for 8 weeks. The result: faster weight gain from larger surpluses primarily increased fat gain, not muscle thickness or strength.

Similarly, Garthe et al. (2013) found that elite athletes in a larger surplus gained 5x more fat with no significant difference in lean mass or strength compared to those in a smaller surplus (European Journal of Sport Science).

A 2019 narrative review on off-season nutrition for bodybuilders recommends a surplus of ~10-20% above maintenance, targeting weight gain of 0.25-0.5% of body weight per week (Iraki et al., Sports, 2019).

In practical terms:

If you don't know your maintenance calories, use our macro calculator or read our guide on how to calculate your TDEE.

Step 1: Set Your Protein

The Morton et al. (2018) meta-analysis of 49 studies found that protein intakes beyond approximately 1.6 g/kg/day did not further increase lean mass gains, with the upper 95% confidence interval at 2.2 g/kg/day (British Journal of Sports Medicine).

The ISSN recommends 1.4-2.0 g/kg/day for building and maintaining muscle mass (Jager et al., JISSN, 2017).

Practical recommendation: Aim for 0.7-1.0 g per pound of body weight (1.6-2.2 g/kg). During a bulk you have more calories to work with, so hitting this target is easier than during a cut.

Schoenfeld and Aragon (2018) also recommend distributing protein across at least 4 meals at roughly 0.4 g/kg per meal to maximize muscle protein synthesis throughout the day (JISSN).

Step 2: Set Your Fat

Fat is essential for hormone production — particularly testosterone, which plays a key role in muscle building. A 2021 meta-analysis found that low-fat diets significantly decreased testosterone levels in men (Whittaker & Wu, J Steroid Biochem Mol Biol).

The ISSN recommends 20-35% of calories from fat for athletes (Aragon et al., JISSN, 2017). Iraki et al. (2019) recommend 0.5-1.5 g/kg/day during the off-season.

Practical recommendation: Set fat at 25-30% of total calories. This ensures adequate hormone support without displacing too many calories from carbs (which fuel your training).

Step 3: Fill the Rest with Carbs

Carbohydrates fuel resistance training by replenishing muscle glycogen — your muscles' primary energy source during intense exercise. The ACSM, Academy of Nutrition and Dietetics, and Dietitians of Canada jointly recommend 3-5 g/kg/day of carbs for moderate-intensity training and 5-7 g/kg/day for moderate to high-intensity daily exercise (Thomas et al., Medicine and Science in Sports and Exercise, 2016).

Insulin — released when you eat carbs — also plays a role in muscle maintenance. A systematic review found that while insulin doesn't directly increase muscle protein synthesis, it significantly reduces muscle protein breakdown, providing an anti-catabolic effect (Abdulla et al., Diabetologia, 2016).

Practical recommendation: After setting protein and fat, fill all remaining calories with carbs. For most people bulking, this works out to 40-55% of total calories from carbohydrates.

Putting It Together: Worked Example

A 180 lb (82 kg) man with a TDEE of 2,600 calories who wants to lean bulk:

• Calorie target: 2,600 × 1.15 = ~2,990 cal/day (15% surplus)
• Protein: 180 lbs × 0.9 g/lb = 162 g protein (648 cal)
• Fat: 27% of 2,990 = 807 cal = 90 g fat
• Carbs: 2,990 − 648 − 807 = 1,535 cal = 384 g carbs

Final macros: 162 g protein / 384 g carbs / 90 g fat (~2,990 cal).

At 0.25-0.5% body weight gain per week, this person should gain roughly 0.45-0.90 lbs per week. If they're gaining faster than that, reduce the surplus — the extra weight is mostly fat.

Realistic Muscle Gain Rates

One of the biggest mistakes in bulking is expecting too much too fast. Muscle grows slowly. Here are realistic expectations for natural lifters, based on widely cited practitioner models by Lyle McDonald and Alan Aragon that align with the peer-reviewed weight gain targets from Iraki et al. (2019):

This means if you're gaining 4+ lbs per month as an intermediate lifter, most of that is fat — not muscle. Scale your surplus to match realistic muscle gain rates.

When to Start and Stop Bulking

Research on nutrient partitioning shows that leaner individuals partition more calories toward muscle, while those with higher body fat store more as fat. Forbes (2000) found that thin individuals gained 60-70% lean tissue during overfeeding, while obese individuals gained only 30-40% lean tissue (Annals of the New York Academy of Sciences).

Based on this research, evidence-informed guidelines suggest:

• Men: Start bulking around 10-12% body fat. Stop and transition to a cut around 15-18% body fat.
• Women: Start bulking around 18-22% body fat. Stop and transition to a cut around 25-28% body fat.

If you're above these ranges, consider cutting first to improve your calorie partitioning before starting a bulk. See our macros for weight loss guide for cutting macro recommendations.

Common Bulking Mistakes

• Eating too much. A 1,000-calorie surplus doesn't build twice as much muscle as a 500-calorie surplus. It builds the same amount of muscle plus a lot more fat.
• "Dirty bulking." Eating anything and everything to get calories in. You still need adequate protein, micronutrients, and fiber. Pizza and ice cream don't build more muscle than chicken and rice at the same calorie level.
• Neglecting carbs. Some people keep carbs low while bulking. Carbs fuel your training and support glycogen replenishment — cutting them limits your performance in the gym, which limits muscle growth.
• Not tracking at all. "Just eat more" often means eating too much or not enough protein. Tracking macros during a bulk is just as important as during a cut.
• Bulking too long. Gaining 30+ lbs before cutting means months of dieting to lose the excess fat. Shorter bulk/cut cycles (gain 10-15 lbs, cut 5-8 lbs) are more efficient and keep you in the body fat range where calorie partitioning favors muscle.

Track Your Bulking Macros with AI

Use the free macro calculator to get your bulking calorie and macro targets. Then try MacroChat free for 3 days to track your macros by voice, photo, or text — and use the AI meal planner to generate high-calorie, high-protein meal plans that actually hit your bulking targets.

Sources

• Helms ER, et al. "Effect of Small and Large Energy Surpluses on Strength, Muscle, and Skinfold Thickness in Resistance-Trained Individuals." Sports Medicine – Open, 2023. Read study
• Garthe I, et al. "Effect of nutritional intervention on body composition and performance in elite athletes." European Journal of Sport Science, 2013. Read study
• Iraki J, et al. "Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review." Sports, 2019. Read review
• Morton RW, et al. "A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains." British Journal of Sports Medicine, 2018. Read study
• Jager R, et al. "ISSN position stand: protein and exercise." Journal of the International Society of Sports Nutrition, 2017. Read position stand
• Schoenfeld BJ, Aragon AA. "How much protein can the body use in a single meal for muscle-building?" Journal of the International Society of Sports Nutrition, 2018. Read study
• Thomas DT, Erdman KA, Burke LM. "ACSM Joint Position Statement: Nutrition and Athletic Performance." Medicine and Science in Sports and Exercise, 2016. Read statement
• Abdulla H, et al. "Role of insulin in the regulation of human skeletal muscle protein synthesis and breakdown: a systematic review and meta-analysis." Diabetologia, 2016. Read study
• Whittaker J, Wu K. "Low-fat diets and testosterone in men: systematic review and meta-analysis." Journal of Steroid Biochemistry and Molecular Biology, 2021. Read study
• Aragon AA, et al. "ISSN position stand: diets and body composition." Journal of the International Society of Sports Nutrition, 2017. Read position stand
• Forbes GB. "Body fat content influences the body composition response to nutrition and exercise." Annals of the New York Academy of Sciences, 2000. Read study