How many calories should you actually eat?

Estimating your starting number

The common formulas (Mifflin-St Jeor is the usual default) estimate your basal rate from weight, height, age, and sex, then multiply by an activity factor between about 1.2 (desk-bound) and 1.9 (hard physical work or twice-a-day training). Most people with a job and a few workouts a week land between 1.4 and 1.6.

Treat the result as a starting guess, not a verdict. Formulas carry an error margin of 10 to 15 percent either way, and your honest activity level is easy to overrate, so most people should pick the multiplier below the one that flatters them.

Deficit or surplus: sizing it

Once you have a maintenance estimate, size the adjustment by how fast you want your bodyweight to change. A useful anchor is 0.25 to 1 percent of bodyweight per week: the lower end for keeping muscle and sanity, the upper end only for a short push.

In practice:

• Fat loss: 300–600 kcal below maintenance, roughly 0.25–0.75% of bodyweight per week.
• Recomposition or maintenance: eat at your estimate and let training drive the change.
• Lean muscle gain: 150–300 kcal above maintenance. Gaining faster mostly means gaining fat.

Formulas start, data decides

Here's the part calculators can't do: your real TDEE reveals itself in the relationship between what you log and what the scale does. Eat a logged 2,200 calories a day for three weeks while your weight trend holds flat, and your TDEE is about 2,200, whatever any formula said.

That's the loop worth automating. Log your food, weigh in a few times a week, and watch the moving average rather than any single reading. MacroTrackr's trends view plots exactly that weekly trajectory, so adjusting your budget becomes a two-minute read instead of a leap of faith. If two to three weeks pass without movement in the direction you want, shift your daily budget by 100–200 calories and watch again.

When to eat at maintenance

Not every phase should be a cut or a bulk. After a long dieting stretch, a few weeks at maintenance lets hunger, energy, and gym performance normalize while you keep the result. High-stress periods (new job, bad sleep, exam season) are also better spent holding steady than fighting a deficit with a tired brain.

Maintenance is also where you graduate to eventually: eating the right amount mostly on autopilot, with tracking as an occasional calibration tool instead of a daily obligation.

Why calculators disagree with each other

Run your numbers through three TDEE calculators and you will get three answers, often 300 calories apart. They are not broken. Each uses a different equation (Mifflin-St Jeor, Harris-Benedict, Katch-McArdle) fitted to a different population, and each asks you to slot yourself into an activity multiplier that spans a huge range.

The activity multiplier is where most of the error lives. "Moderately active" means something different to a builder who lifts three times a week and to a desk worker who walks the dog. The equations are fine; the input is a guess. Treat any calculator output as a starting hypothesis with a margin of a few hundred calories, not a measurement.

Adjusting when the number stops working

Your TDEE is not fixed. It falls as you lose weight, because a smaller body costs less to run, and it drifts with how much you move outside the gym: the fidgeting, walking and general restlessness that quietly accounts for a large slice of daily burn, and that tends to drop during a long deficit.

So expect to recalculate. A practical rule: when the weekly average has been flat for three weeks and your logging is honest, cut 10 percent from calories or add a deliberate 2,000 steps a day, then hold for another three weeks. Alternate between those two levers rather than pulling one repeatedly. Cutting calories forever ends somewhere unpleasant.

If you are cutting, this is also the point to check that protein has not drifted down with everything else. It is the macro that protects muscle while the deficit does its work.