To build muscle, most lifters need 250–500 calories above maintenance each day, with protein at 1.6–2.2 grams per kilogram of bodyweight. To lose fat, the mirror image works: 300–500 calories below maintenance, with protein toward the higher end so the weight you lose is fat, not muscle. Maintenance — the calories you burn in a full day — is the number everything hangs on, and you can estimate it in two minutes with the Mifflin-St Jeor equation below. This guide walks through that calculation with real numbers, then shows how to adjust it.
In This Guide
- Find Your Maintenance Calories
- Build Muscle: Add a Small Surplus
- Lose Fat: Subtract a Moderate Deficit
- Protein Decides What the Calories Become
- Build Muscle and Lose Fat at the Same Time?
- The 2-Week Check
- 4 Calorie Mistakes That Waste Months
- FAQ
Step 1: Find Your Maintenance Calories
Every calorie target starts from one number: your maintenance, or total daily energy expenditure (TDEE). Eat at it and your weight holds; above it, you gain; below it, you lose. Guessing this number is the most common reason diets stall — two people of the same weight can burn very different amounts.
Maintenance is your basal metabolic rate (BMR) — what you burn just staying alive — plus walking, working, training, and digesting food. The standard BMR estimate is the Mifflin-St Jeor equation, published in 1990 and still the formula most dietitians reach for.
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
Then multiply by an activity factor to get your TDEE:
| Activity level | Multiplier | What it means |
|---|---|---|
| Sedentary | × 1.2 | Desk job, no exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days/week |
| Moderately active | × 1.55 | Training 3–5 days/week |
| Very active | × 1.725 | Hard training 6–7 days/week |
| Extra active | × 1.9 | Hard training + physical job |
Worked example. A 28-year-old man, 80 kg (176 lb), 180 cm (5’11”), lifting four days a week: BMR = (10 × 80) + (6.25 × 180) − (5 × 28) + 5 = 1,790 calories; × 1.55 gives maintenance of about 2,775 a day. Treat that as a starting point — formulas like this are typically accurate within about 10 percent, so the two-week check below matters more. Our Calorie Calculator runs the same calculation for you.
To Build Muscle: Add a Small Surplus
Muscle is expensive tissue to build, and your body will not build much of it without extra energy. A 2019 review in Sports (Iraki and colleagues) recommends a surplus of roughly 10–20 percent above maintenance for novice and intermediate lifters — 250–500 extra calories on a 2,500-calorie maintenance. A randomized trial in Medicine & Science in Sports & Exercise found the same: muscle growth leveled off beyond a 300–500 calorie surplus.
| Your maintenance | Muscle-gain target | Lean-bulk start |
|---|---|---|
| 2,000 kcal | 2,250–2,500 kcal | 2,200–2,300 kcal |
| 2,500 kcal | 2,750–3,000 kcal | 2,700–2,800 kcal |
| 3,000 kcal | 3,250–3,500 kcal | 3,200–3,300 kcal |
Back to our 28-year-old: his muscle-gain target is roughly 3,025–3,275 calories a day, and starting at the low end, around 3,050, is smarter if staying lean matters. A reasonable rate is 0.25–0.5 percent of bodyweight per week — for him, 0.2–0.4 kg (0.5–0.9 lb) a week; faster than that and the extra weight is mostly fat. And no surplus replaces training: extra calories without progressive resistance training just become body fat. Still deciding whether to gain or lean out first? Our bulking vs cutting guide walks through that decision, and the Build Muscle hub covers the training side.
To Lose Fat: Subtract a Moderate Deficit
Fat loss works the same way in reverse: a deficit of 300–500 calories below maintenance, which most lifters can sustain for months. A 500-calorie daily deficit adds up to about 1 lb (0.45 kg) per week.
Worked example. A 32-year-old woman, 65 kg (143 lb), 165 cm (5’5″), training lightly three days a week: BMR = (10 × 65) + (6.25 × 165) − (5 × 32) − 161 = 1,360 calories; × 1.375 gives maintenance of about 1,870 a day, so her fat-loss target is roughly 1,370–1,570 — start near 1,550, and adjust down only if progress stalls.
A sensible rate is 0.5–1 percent of bodyweight per week: for her, about 0.3–0.65 kg (0.7–1.4 lb) a week. Two guardrails matter. First, do not drop below about 1,200 calories a day for women or 1,500 for men without medical supervision. Second, keep protein high: athletes in a deficit eating around 1.8–2.4 g/kg per day, combined with intense training, preserved lean mass far better than lower intakes (Longland and colleagues, 2016). For training on a cut, see the Lose Fat hub; for the traps that stall progress, 7 fat loss mistakes that keep you stuck.
Protein Decides What the Calories Become
Calories decide whether your weight moves up or down; protein decides what that weight is made of.
The International Society of Sports Nutrition puts 1.4–2.0 g/kg per day as sufficient for most people who exercise, and a meta-analysis by Morton and colleagues (2018) — 49 studies, 1,863 participants — found the benefits for muscle growth leveled off at about 1.6 g/kg per day. A practical target is 1.6–2.2 g/kg — lower end while gaining, higher end while cutting.
| Bodyweight | Muscle gain | Fat loss |
|---|---|---|
| 60 kg (132 lb) | ~96 g/day | 120–132 g/day |
| 70 kg (154 lb) | ~112 g/day | 140–154 g/day |
| 80 kg (176 lb) | ~128 g/day | 160–176 g/day |
| 90 kg (198 lb) | ~144 g/day | 180–198 g/day |
Spread it across the day — about 20–40 g per meal. The Protein Calculator turns your bodyweight and goal into a daily gram target in seconds.
Can You Build Muscle and Lose Fat at the Same Time?
Sometimes — but not for everyone. Beginners, people returning after a long break, and lifters carrying a lot of body fat can often do both at once, eating around maintenance with protein at the high end. For an experienced, lean lifter, the overlap mostly disappears: muscle gain wants a surplus, fat loss wants a deficit. Pick a direction for eight to twelve weeks, then switch.
The 2-Week Check: How to Adjust Your Number
Your first calorie target is an educated guess, and the scale is how you test it — one weigh-in proves nothing, since bodyweight swings a kilogram or more day to day. The method that works is boring on purpose:
- Weigh yourself every morning, before eating.
- Compare weekly averages, not single days. Add up seven mornings and divide by seven.
- Hold the target for two full weeks before changing anything.
- Adjust by 100–200 calories at a time. Gaining faster than 0.5 percent of bodyweight a week, drop 150; losing nothing after two weeks in a deficit, drop 150; losing faster than 1 percent a week, add 150 back.
- Recalculate after real change. If your weight moves 5–10 lb (2–5 kg) either way, or your training volume changes a lot, run the formula again.
Treat the target as a starting point, corrected every two weeks.
4 Calorie Mistakes That Waste Months
1. Guessing your maintenance instead of calculating it. “I probably burn about 3,000” is not a plan — two people with the same desk job can differ by hundreds of calories a day. Spend two minutes on the formula, then let the scale correct it.
2. The 1,000-calorie dirty bulk. Eating everything in sight builds muscle — and a lot of fat alongside it. Beyond a 300–500 calorie surplus, extra muscle gain flattens out while fat gain keeps climbing.
3. The crash deficit. Slashing 1,000 calories on day one feels productive for about a week — then hunger, fatigue, and stalled lifts show up, and most people quit. A 300–500 calorie deficit held for three months beats a 1,000-calorie deficit abandoned in three weeks.
4. Changing your target every day. The scale jumps after a salty dinner and people panic-cut 300 calories; it drops after a light day and they add a cheat meal. Daily noise is not data — adjust on weekly averages only.
FAQ
How many calories do I need to build muscle?
Maintenance plus 250–500 calories per day, with protein at 1.6–2.2 g per kilogram of bodyweight. Start low, track your weekly average weight for two weeks, and add 100–200 calories only if the scale is not moving.
Can I build muscle in a calorie deficit?
Yes, if you are a beginner, returning after time off, or carrying higher body fat — especially with high protein and hard training. Experienced, lean lifters will struggle to add noticeable muscle without a surplus.
How fast should I gain or lose weight?
Muscle gain: 0.25–0.5 percent of bodyweight per week; fat loss: 0.5–1 percent. Faster than that usually means the extra weight is fat on the way up, or muscle on the way down.
Do I have to count calories forever?
No. Four to eight weeks of honest tracking teaches most people what their portions contain. After that, eat roughly the same meals, check the scale weekly, and track again whenever progress stalls.
A Quick Safety Note
Everything here is general information, not medical advice, for healthy adults who lift. If you have a medical condition, take medication that affects appetite or metabolism, are pregnant, or have a history of disordered eating, talk to your doctor or a registered dietitian before changing how much you eat. Dizziness, constant exhaustion, or a lost period on a deficit are signs to eat more and get checked — not to push harder.
References
- Mifflin MD, et al. (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 51(2), 241–247. doi.org/10.1093/ajcn/51.2.241
- Iraki J, et al. (2019). Nutrition recommendations for bodybuilders in the off-season: A narrative review. Sports, 7(7), 154. doi.org/10.3390/sports7070154
- Morton RW, et al. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, 52, 376–384. doi.org/10.1136/bjsports-2017-097608
- Jäger R, et al. (2017). International Society of Sports Nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14, 20.
- Longland TM, et al. (2016). Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: A randomized trial. American Journal of Clinical Nutrition, 103(3), 738–746. doi.org/10.3945/ajcn.115.119339