Most people trying to build muscle get one of two things wrong: they eat far too large a surplus and gain mostly fat, or they are so afraid of fat gain that they never eat enough to build anything. The useful range is narrower than either.
Start With Maintenance
Everything is set relative to maintenance — the intake at which your weight is stable. Estimate it, then correct it with real data.
A reasonable starting estimate is 30–33 calories per kg of body weight per day for someone who trains 3–5 times a week. For an 80kg person that is roughly 2,400–2,650 calories.
Then verify it: eat at that estimate for two weeks, tracking consistently, and watch the weekly average weight. Flat means you found maintenance. Moving means adjust by 200 calories and repeat. No formula beats two weeks of your own data.
Set the Surplus: 10–20%
Muscle is built slowly and there is a hard ceiling on how fast it can be added. Eating far above that ceiling does not accelerate it — the excess becomes fat.
On 2,500 maintenance calories that is a surplus of roughly 250–500 per day.
Realistic expectations matter here. A well-trained beginner might add 0.5–1kg of muscle per month in their first year. That falls sharply afterwards. Anyone gaining 2kg a month is gaining mostly fat.
Target roughly 0.25–0.5% of body weight gained per week. For an 80kg person, 200–400g. Faster than that and the extra is not muscle.
Protein: 1.6–2.2g per kg
This is the most researched number in sports nutrition, and the evidence is consistent: intakes around 1.6g per kg of body weight per day capture most of the benefit for muscle growth, with modest additional benefit up to roughly 2.2g.
For an 80kg person that is 128–176g of protein per day. Practical notes:
Fat: Do Not Go Too Low
Fat matters for hormone production and general health, and it is easy to cut too far when protein and carbs are both being pushed up.
Keep fat at a minimum of 0.6–0.8g per kg of body weight — roughly 48–64g for an 80kg person. Most people do well somewhere between 20% and 30% of total calories.
Carbs: Whatever Is Left
Carbohydrate is not essential in the way protein and fat are, but it is the fuel that lets you train hard enough to justify the surplus. Once protein and fat are set, carbs fill the remaining calories.
For an 80kg person eating 2,800 calories to gain:
If training feels flat and sessions are getting worse rather than better, carbs are usually the first thing to raise.
Track the Right Things
Weight alone will not tell you whether the surplus is working. Watch these together:
If the scale is climbing but strength is flat and your waist is growing, cut the surplus by 200 calories.
Adjust Slowly
Reassess every three to four weeks against averages, not individual days. Change one variable at a time and give it a fortnight before judging. Bodyweight, training performance and waist measurement together will tell you what to do next far more reliably than any calculator.
