How Many Calories Should I Eat to Lose Weight?

What a Calorie Deficit Actually Is

A calorie is a unit of energy. Your body needs a certain amount of it every day just to exist — to breathe, pump blood, digest food, maintain body temperature, and move around. That number is your maintenance calories, or TDEE (Total Daily Energy Expenditure). It's the exact point where your weight stays stable.

Eat above that number consistently, and your body stores the surplus as fat. Eat below it consistently, and your body starts burning stored fat to make up the difference. That's the entire mechanism of fat loss. Every diet — keto, intermittent fasting, low-fat, high-protein — works when it works because it puts you in a calorie deficit. The diet is the vehicle. The deficit is the engine.

Understanding this matters because it stops you chasing the wrong thing. You don't need a specific diet. You don't need to cut carbs or eat at specific times or avoid certain foods. You need to eat fewer calories than you burn — and do it in a way you can sustain for weeks and months, not days.

Step 1 — Find Your TDEE

Before you can set a deficit, you need to know your starting point: how many calories your body burns on an average day. This is your TDEE. It has two components — your BMR, and an activity multiplier applied on top.

First: calculate your BMR

Your Basal Metabolic Rate (BMR) is the number of calories your body burns at complete rest — just to keep you alive. The most widely validated formula for calculating it is the Mifflin-St Jeor equation, which outperforms older formulas like Harris-Benedict in accuracy across most populations.

Then: multiply by your activity level

Your BMR only covers resting metabolism. Every step you take, every workout, and even the energy used to digest food adds to your total burn. To get your TDEE, multiply your BMR by the activity factor that best matches your real daily life — not the life you aspire to.

If maths isn't your thing, our TDEE calculator guide walks through this with an interactive tool you can use right now.

Step 2 — Set Your Deficit

Once you know your TDEE, setting your calorie target for fat loss is simple: subtract a deficit from it. The question is how big that deficit should be.

Bigger deficits produce faster weight loss on paper — but they come with real costs. Too aggressive and you lose muscle alongside fat, your energy tanks, hunger becomes unmanageable, and compliance collapses within weeks. The research is clear: moderate, sustainable deficits produce better body composition outcomes over time than aggressive short cuts.

A Real Worked Example

Let's run this for a real person so the numbers become concrete.

Profile: Male, 30 years old, 80 kg, 178 cm tall. Works a desk job, trains in the gym 3 times a week.

Expected result: roughly 0.35–0.45 kg of fat loss per week, assuming accurate tracking and consistent adherence. Over 12 weeks, that's 4–5 kg — entirely realistic without crash dieting, starvation, or eliminating any food group.

Why Most People Get This Wrong

The formula is simple. The execution trips people up in a few predictable ways.

Underestimating how much they're eating

Studies consistently show that people underreport their calorie intake by 20–40%. Not because they're lying — because estimating portions is genuinely hard. A tablespoon of olive oil "eyeballed" is often two tablespoons, which is an extra 120 kcal you didn't account for. A handful of mixed nuts is 200+ kcal that rarely gets logged. If you're eating at a deficit on paper but the scale isn't moving, this is the first place to look. Weighing food for even two weeks builds a calibration that changes how you estimate forever.

Setting the deficit too aggressively from day one

Starting with a 1,000 kcal deficit because you want faster results almost always backfires. Hunger spikes, performance tanks, adherence falls apart within two to three weeks, and you end up back where you started having lost mostly water weight and some muscle. A slower deficit you can maintain for three months beats an aggressive one you quit after three weeks every time.

Not protecting protein

Cutting calories without hitting your protein target is the fastest route to losing muscle instead of fat. In a deficit, your body looks for energy anywhere it can find it — including breaking down muscle tissue. High protein intake (1.6–2.2g/kg) combined with resistance training sends a strong signal to preserve muscle while burning fat. Cutting calories and protein simultaneously undermines the whole point.

Treating weekends as separate from the week

A 500 kcal deficit Monday through Friday followed by a 1,000 kcal surplus Saturday and Sunday doesn't produce fat loss — it produces a net weekly surplus. Your body doesn't reset at midnight on Friday. Calorie balance is cumulative. Weekends count.

How to Adjust When Progress Stalls

Here's something nobody tells you upfront: the calorie target you calculate today will stop working eventually. Not because the formula was wrong, but because your body adapts.

As you lose weight, your BMR decreases — you're a lighter person burning fewer calories at rest. On top of that, metabolic adaptation means your body becomes more efficient during exercise and reduces non-exercise movement (fidgeting, spontaneous walking) without you noticing. The result is that a deficit that produced 0.4 kg/week in month one might produce 0.1 kg/week in month three on the same calories.

This isn't a reason to panic or crash your calories. It's a signal to make a small, calculated adjustment.

The Bottom Line

How many calories should you eat to lose weight? Here's your answer: calculate your TDEE using the Mifflin-St Jeor formula and your real activity level, then subtract 300–500 kcal. That's your number. That's where you start.

Everything else — the specific diet, the meal timing, the foods you include or avoid — is secondary to that number. Build your eating around a calorie target that creates a real deficit, protect your protein intake, and give it time. The math works. Most people just never calculate it properly to begin with.

If the scale stops moving, recalculate. If you've lost 5 kg, your TDEE has changed — run the numbers again with your new weight. Treat it like a living calculation, not a one-time event.