How Many Calories to Lose Weight?

Losing weight sounds complicated, but at its core it's math: take in less energy than you burn over time, and the weight comes off. The trick is finding the right number – not too little, not too much.

You don't need to be a nutrition scientist to estimate your calorie needs. Three terms are enough: basal metabolic rate, total daily burn, and deficit. We'll go through them in order, and by the end you'll have a concrete number to start with.

Step 1: Your basal metabolic rate

Your basal metabolic rate (BMR) is the energy your body uses at complete rest – for breathing, your heartbeat, your brain. A reliable estimate is the Mifflin-St Jeor equation:

This is an estimate, not a lab reading. Real people deviate from it – but as a starting point the formula is surprisingly useful.

Step 2: Your total daily burn

You're not lying in bed all day. Multiply your BMR by an activity factor (PAL) to get your total daily energy expenditure (TDEE) – everything you burn on a normal day:

• Mostly sedentary (desk job, little exercise): × 1.3–1.4
• Lightly active (some movement, 1–2 workouts/week): × 1.5
• Active (3–5 workouts/week): × 1.6–1.7
• Very active (daily training or a physical job): × 1.8+

Our example woman, lightly active: 1,414 × 1.5 ≈ 2,120 kcal. That's roughly what she needs to maintain her weight.

Step 3: The deficit

Now the part that actually drives weight loss. One kilogram of body fat is roughly 7,000 kcal. Subtract about 300–500 kcal from your daily burn and you'll lose around 0.3–0.5 kg per week on average. That's slow enough to protect your muscle and to keep going.

For our example: 2,120 − 400 ≈ 1,720 kcal per day. Want to go faster? Tempting, but it usually backfires: stronger hunger, more muscle loss, and a bigger chance you end up raiding the fridge.

The best deficit isn't the biggest – it's the one you can hold for months without hating your life.

Why the number is only half the story

Calorie calculators are estimates, not guarantees. Your burn swings day to day, your body adapts, and package labels have tolerances. So treat your target as a starting point, not sacred law. After two or three weeks the scale and the mirror will tell you whether to adjust – that's the most honest feedback there is.

One important note: don't stay below your BMR long-term. Eating too little doesn't just slow your progress, it makes sticking with it nearly impossible. Individual differences are large here – when in doubt, a registered dietitian can help.

The most common pitfalls

• Forgetting liquid calories. Juice, lattes, an after-work beer – they slip past your attention but show up fully in the math.
• Underestimating oil and sauces. A tablespoon of olive oil is around 100 kcal. When you fry, more ends up in the pan than you think.
• Ignoring the weekend. Five disciplined days don't save a weekend with two restaurant visits. Count the week, not the day.
• "Earning back" exercise. Calories burned are easy to overestimate. Don't eat back everything your smartwatch credits you.

Do I have to count forever?

No. Counting calories is a tool, not a lifestyle. Most people need it for a few weeks to build a sense of portions – what 30 g of protein looks like, how fast snacks add up. After that you carry that instinct in your head and can take a looser approach to tracking. Think of the number as driving school, not a lifelong companion.

The short version

• Estimate your BMR (Mifflin-St Jeor).
• Scale it up with an activity factor to get your total burn.
• Subtract 300–500 kcal – no more.
• Watch for 2–3 weeks, then adjust.