Understanding TDEE and Calorie Needs
Total Daily Energy Expenditure (TDEE) represents the total calories your body burns daily through all activities. Understanding TDEE is fundamental to weight management—eating below TDEE causes weight loss, eating at TDEE maintains weight, and eating above TDEE leads to weight gain. Our calculator uses the Mifflin-St Jeor equation, considered the most accurate modern formula for calculating calorie needs based on age, gender, weight, height, and activity level.
BMR vs TDEE: What's the Difference?
Basal Metabolic Rate (BMR): Calories burned at complete rest, maintaining essential body functions (breathing, circulation, cell production). BMR accounts for 60-75% of daily calorie burn for sedentary people. The Mifflin-St Jeor formula calculates BMR based on age (older = lower BMR), weight (heavier = higher BMR), and gender (men typically have higher BMR than women).
Total Daily Energy Expenditure (TDEE): BMR multiplied by activity factor. TDEE = BMR × Activity Level. A sedentary person's TDEE might be BMR × 1.2, while an athlete's might be BMR × 1.9. TDEE provides the realistic daily calorie burn accounting for your actual lifestyle.
Activity Level Factors Explained
Sedentary (1.2): Little exercise, office job, minimal movement. Multiply BMR by 1.2. Example: BMR 1,800 × 1.2 = 2,160 TDEE.
Lightly Active (1.375): Light exercise 1-3 days weekly. Includes desk job plus gym sessions 2-3x per week. Multiply BMR by 1.375.
Moderately Active (1.55): Exercise 3-5 days weekly, or physical job. Includes regular workouts plus active job. Multiply BMR by 1.55.
Very Active (1.725): Intense exercise 6-7 days weekly or physical job plus exercise. Multiply BMR by 1.725.
Extremely Active (1.9): Professional athlete or physical laborer. Intense activity 6-7 days weekly. Multiply BMR by 1.9.
Using TDEE for Weight Loss, Maintenance, or Gain
Weight Loss: Consume 300-500 calories below TDEE. This creates a deficit yielding roughly 0.5-1 lb weekly loss (sustainable, healthy rate). Never consume below 1,200 calories (women) or 1,500 calories (men) without medical supervision.
Maintenance: Consume at TDEE level. Weight remains stable. Useful for maintaining fitness without gaining fat or losing muscle.
Muscle Gain: Consume 300-500 calories above TDEE plus strength training. Excess calories support muscle growth. Higher surplus leads to more fat gain alongside muscle.
The Mifflin-St Jeor Formula
Our calculator uses the Mifflin-St Jeor equation, developed in 1990 and considered the most accurate for average adults. For men: BMR = (10×weight_kg) + (6.25×height_cm) - (5×age) + 5. For women: BMR = (10×weight_kg) + (6.25×height_cm) - (5×age) - 161. This formula accounts for how metabolism decreases with age (roughly 2% per decade after 20) and varies by gender.
Factors Affecting Your Actual TDEE
While our calculator provides accurate estimates, actual TDEE varies individually. Metabolic disorders (thyroid disease, PCOS) affect calorie burn. Medications impact metabolism. Genetics influence BMR. Sleep quality affects hunger hormones and calorie burn. Stress increases cortisol, affecting metabolism and hunger. Muscle mass increases TDEE (muscle is metabolically active). Temperature exposure affects calorie burn. Track weight changes for 2-3 weeks to assess if actual TDEE matches estimates, then adjust accordingly.
Tips for Accurate Calorie Management
- Use kitchen scale for portions: Food measurements (cups, handfuls) are imprecise. Digital scales ensure accuracy
- Account for cooking oils: Oils add significant calories. Track cooking fats in your calorie total
- Track consistently for 2-3 weeks: See actual results before adjusting. Weight fluctuates daily
- Adjust for plateaus: If weight stalls, reduce calories by 100-150 as metabolism adapts
- Prioritize protein: Higher protein intake supports muscle preservation during weight loss and increases satiety
- Monitor hunger cues: Extreme hunger indicates excessive deficit. Adjust calories upward slightly