How to Calculate Calories for Weight Loss

Overview

Calculating calories for weight loss comes down to one core equation: consume fewer calories than your body burns each day. The challenge is that most people do not know how many calories they burn — and guessing leads to either too little progress or an unsustainably large deficit that stalls after a few weeks.

This guide walks you through a four-step process: finding your TDEE (the total number of calories your body actually uses each day), setting an appropriate calorie deficit, calculating your macronutrient targets, and adjusting your numbers when progress stalls. At the end, you will have a specific daily calorie target and a method for keeping it accurate as your weight changes.

Use the TDEE Calculator and Calorie Calculator alongside this guide to run the numbers for your own body.

What You Need

Your current weight in kilograms
Your height in centimetres
Your age in years
An honest assessment of your weekly activity level
A food tracking app or a method for logging what you eat

Step 1: Calculate Your TDEE

TDEE — Total Daily Energy Expenditure — is the number of calories your body burns in a typical day. It is calculated in two parts: first your BMR, then multiplied by an activity factor.

Calculate BMR using the Mifflin-St Jeor equation:

Men: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age) + 5
Women: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age) − 161

Mifflin-St Jeor is the most widely recommended formula because it performs well across a broad range of body types. The older Harris-Benedict formula overestimates BMR by 5–15% in most people and is best avoided.

Apply your activity multiplier:

Activity Level	Multiplier	Description
Sedentary	1.2	Desk job, no intentional exercise
Lightly active	1.375	Exercise 1–3 days/week
Moderately active	1.55	Exercise 3–5 days/week
Very active	1.725	Hard exercise 6–7 days/week
Extra active	1.9	Physical job + daily training

Most people should start at a slightly lower multiplier than feels accurate. Underestimating activity is far safer than overestimating, since overestimation creates a phantom deficit that doesn't translate to actual weight loss.

Use the TDEE Calculator to get your number instantly without manual arithmetic.

Step 2: Set a Calorie Deficit

Once you have your TDEE, subtract a specific number of calories to create a deficit:

Moderate deficit (−300 to −500 kcal/day): Sustainable, preserves muscle, results in 0.25–0.45 kg/week loss. Recommended for most people.
Aggressive deficit (−750 to −1,000 kcal/day): Results in 0.7–0.9 kg/week but increases muscle loss and hunger. Use only for limited periods under medical guidance.

Hard floors — do not go below these levels:

Women: 1,200 kcal/day
Men: 1,500 kcal/day

Going below these thresholds triggers metabolic adaptation — the body lowers TDEE in response to severe restriction by reducing spontaneous movement, lowering body temperature, and slowing metabolic processes. This makes sustained weight loss progressively harder.

A rate of 0.5–1% of bodyweight per week is generally considered safe and sustainable. For a 70 kg person, that is 0.35–0.7 kg per week.

Step 3: Calculate Protein, Carb, and Fat Targets

Your calorie target is only part of the picture. Macronutrient distribution determines how much of the weight you lose is fat versus muscle.

Set protein first. Research consistently shows that higher protein intake during a calorie deficit preserves lean muscle mass. Target 1.6–2.2 g per kg of bodyweight. For a 70 kg person, that is 112–154 g of protein per day. Since protein provides 4 kcal per gram, 130 g of protein accounts for 520 kcal.

Set fat second. Fat is essential for hormone production and fat-soluble vitamin absorption. Keep fat at a minimum of 0.7 g per kg of bodyweight. For a 70 kg person, this is at least 49 g of fat per day. Fat provides 9 kcal per gram, so 49 g = 441 kcal.

Fill remaining calories with carbohydrates. Carbohydrates provide 4 kcal per gram and are the preferred fuel for high-intensity exercise. Subtract your protein and fat calories from your daily target to find your carb allowance.

Worked example: 70 kg woman, TDEE 2,200 kcal, 500 kcal deficit = 1,700 kcal target:

Protein: 130 g × 4 = 520 kcal
Fat: 55 g × 9 = 495 kcal
Carbs: (1,700 − 520 − 495) / 4 = 171 g

Step 4: Track Daily Intake

Tracking food intake is the single highest-leverage behaviour for weight loss success. Studies consistently show that people who track what they eat lose significantly more weight than those who do not.

Key tracking rules:

Weigh food raw (or note whether you are using cooked weights) — 100 g of raw chicken has more protein and calories than 100 g of cooked chicken because water evaporates during cooking.
Log everything — cooking oils, dressings, milk in coffee, and drinks that contain calories are the most commonly forgotten items. A tablespoon of olive oil is 120 kcal; a flat white coffee is 100–150 kcal.
Do not rely on memory — log at the time of eating, not at the end of the day. End-of-day logging misses an average of 400–500 kcal in research studies.
Use the Calories Burned Calculator to estimate exercise output if you want to track your net balance.

Step 5: Adjust After 2–3 Weeks

Your initial calorie target is an estimate. Real-world results tell you whether it is accurate. After 2–3 weeks of consistent tracking:

No weight loss: Drop your daily target by 100–200 kcal and continue for another 2 weeks before reassessing.
Losing too fast (>1% bodyweight/week): Increase your target by 100–150 kcal to slow the rate and reduce muscle loss.
Weight loss stalls after initial progress: Recalculate your TDEE using your new, lower bodyweight. As you lose weight, your BMR falls and your maintenance calories decrease. A 10 kg loss typically reduces TDEE by 150–250 kcal.

Plan to recalculate your TDEE and update your calorie target after every 5 kg of weight loss.

Common Mistakes to Avoid

Cutting too aggressively from day one. Starting with a 1,000 kcal deficit feels fast but typically leads to muscle loss, extreme hunger, and eventual rebound. A 500 kcal deficit achieves meaningful progress while being sustainable for months, not weeks.

Ignoring liquid calories. Juice, soft drinks, alcohol, sports drinks, and calorie-containing coffee beverages are invisible in most food diaries unless deliberately tracked. A single glass of orange juice (200 ml) contains roughly 90 kcal; two beers add 300 kcal. These add up quickly without making you feel full.

Not accounting for exercise adaptation. After 6–8 weeks of regular training, the body becomes more efficient at performing the same movements — burning fewer calories doing the same workout. Progressive overload (increasing weight, intensity, or volume over time) is required to maintain calorie expenditure from exercise.

Failing to recalculate as weight drops. A 90 kg person who loses 15 kg needs roughly 200–250 fewer daily calories at 75 kg to maintain the same rate of loss. Using the original TDEE too long creates a smaller actual deficit than intended, explaining why progress often slows after the first month or two.

Using bathroom scales only. Daily weight fluctuates 1–3 kg due to water, food mass, glycogen, and hormonal variation. Track a 7-day or 14-day rolling average rather than individual daily readings. Tools like the BMI Calculator give context for where your current weight sits relative to healthy ranges.

Formula & Methodology

Mifflin-St Jeor BMR:

Men: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age) + 5
Women: BMR = (10 × weight_kg) + (6.25 × height_cm) − (5 × age) − 161

TDEE: TDEE = BMR × Activity Multiplier

Calorie target: Daily Target = TDEE − Deficit

Worked example: 30-year-old woman, 70 kg, 165 cm, moderately active:

BMR = (10 × 70) + (6.25 × 165) − (5 × 30) − 161
BMR = 700 + 1,031 − 150 − 161 = 1,420 kcal
TDEE = 1,420 × 1.55 = 2,201 kcal
500 kcal deficit: Daily target = 1,701 kcal

This target produces approximately 0.45 kg of weight loss per week, or roughly 2 kg per month — a safe, sustainable rate that minimises muscle loss when combined with adequate protein intake.