How to Calculate Calories: TDEE and BMR Explained

Calories: The Foundation of Weight Management

A calorie is a unit of energy. Everything you eat contains calories; everything you do burns calories. Your weight changes based on the balance between calories consumed and calories expended. Understanding how many calories you need each day is the starting point for any nutrition or fitness goal.

Step 1: Calculate Your BMR

Your Basal Metabolic Rate (BMR) is the number of calories your body needs at complete rest just to maintain basic functions — breathing, circulation, cell repair. The most accurate commonly-used formula is the Mifflin-St Jeor equation:

Mifflin-St Jeor Formula

For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5

For women: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) − 161

Example (woman, 30 years, 65kg, 165cm)

BMR = (10 × 65) + (6.25 × 165) − (5 × 30) − 161
= 650 + 1,031.25 − 150 − 161 = 1,370 calories/day

Step 2: Calculate Your TDEE

Your Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor to account for how active you are:

Activity Level	Description	Multiplier
Sedentary	Little/no exercise, desk job	× 1.2
Lightly active	Light exercise 1–3 days/week	× 1.375
Moderately active	Moderate exercise 3–5 days/week	× 1.55
Very active	Hard exercise 6–7 days/week	× 1.725
Extra active	Very hard exercise + physical job	× 1.9

Example: BMR of 1,370 × 1.55 (moderately active) = 2,124 calories/day TDEE

Calories for Weight Goals

• Maintain weight: Eat at your TDEE
• Lose weight: Eat 500 calories below TDEE per day → approximately 1 lb (0.45 kg) loss per week
• Gain weight: Eat 300–500 calories above TDEE per day for lean muscle gain

A deficit of 3,500 calories roughly equals 1 pound of fat. However, as you lose weight, your BMR decreases (because you weigh less), so you'll need to recalculate periodically.

Food Calorie Reference

Food	Serving	Calories
Chicken breast	100g cooked	165
Brown rice	100g cooked	110
Egg	1 large	72
Avocado	½ medium	120
Almonds	1 oz (28g)	164
Banana	1 medium	89
Olive oil	1 tbsp	119