How many calories should you eat to lose weight?

ActiveDay Team · June 9, 2026 · 4 min read

Weight loss has a reputation for being complicated, but the underlying arithmetic is short: eat fewer calories than your body uses, repeatedly, and weight comes down. The hard part is knowing what "fewer" means for you specifically — and staying honest about it for long enough to matter. This guide walks through finding your number and adjusting it when reality disagrees with the math.

Start with maintenance, not with a diet

Your maintenance calories — total daily energy expenditure, or TDEE — are what your body burns in a normal day: resting metabolism plus movement, training, and digestion. Everything starts from this number, because a deficit is only defined relative to it.

You can estimate TDEE in under a minute with our calorie calculator, which uses the Mifflin-St Jeor equation — the formula with the best track record for healthy adults — and an activity multiplier. A 35-year-old woman, 167 cm and 72 kg, moderately active, lands around 2,200 kcal. A sedentary man of the same age at 183 cm and 95 kg lands near 2,400.

One honest warning: most people overestimate their activity level. Training three evenings a week while sitting the other 70 waking hours is "lightly active," not "very active." When unsure, pick the lower multiplier.

Size the deficit

A kilogram of body fat stores roughly 7,700 kcal. Eat 500 kcal under maintenance daily and you should lose about half a kilogram per week. That pace is the sweet spot for most people:

• 250–300 kcal/day — slow but nearly painless; good for people with little to lose, or anyone protecting maximum muscle and gym performance.
• 500 kcal/day — the standard recommendation; meaningful progress with manageable hunger.
• 750+ kcal/day — faster, but hunger, fatigue, and muscle loss all scale up; harder to sustain past a few weeks.

Whatever you pick, protein becomes more important as the deficit grows — it is what signals your body to burn fat rather than muscle. Aim for the higher end of the range in our protein intake calculator, then split the remaining calories with the macro calculator.

Why the scale will lie to you

Daily weight bounces with water, salt, carbs, and what is simply in transit through you. A salty dinner can add a kilogram overnight; none of it is fat. This noise causes two classic mistakes: panicking at a fake gain, and celebrating a fake loss.

The fix is to compare weekly averages. Weigh in each morning under the same conditions, average the week, and compare that to last week's average. If the weekly average falls at roughly your planned pace, the target is right — regardless of what any single morning said.

Adjust like an engineer, not a dieter

Give any target two to three weeks of honest logging before judging it. Then:

• Losing as planned? Change nothing.
• Losing too slowly or not at all? First tighten logging — cooking oils, sauces, weekend drinks, and bites while cooking are the usual leaks. If four weeks pass with a flat trend and clean logs, drop intake by 100–200 kcal.
• Losing much faster than planned, feeling drained? Add 100–200 kcal back. Faster is not better if it costs muscle and adherence.

Expect maintenance itself to drift down as you get lighter — a smaller body burns less. A 10 kg loss typically lowers TDEE by 150–250 kcal, so plan on recalculating every several kilograms.

The part that actually decides the outcome

The math above fails for one reason far more than any other: the calories you eat and the calories you log are not the same number. Research on self-reported intake finds people under-report by 30 percent or more — not from dishonesty, but because untracked calories are invisible.

This is where tooling earns its keep. Logging every meal by hand is tedious enough that most people quit within weeks. ActiveDay shortens the loop: photograph your plate and the AI camera identifies up to eight foods with verified nutrition, scan a barcode, or pull up recurring meals in two taps. Workouts and steps sync in from Apple Health, and the weekly trend view does the averaging for you.

Pick a sane target, log honestly, read the weekly trend, adjust in small steps. That is the entire system — and it works at any starting weight.