What are BMR and TDEE?
BMR (Basal Metabolic Rate) is the number of calories your body burns at complete rest — just to keep your organs functioning. It accounts for 60–75% of total energy expenditure. TDEE (Total Daily Energy Expenditure) is your BMR multiplied by an activity factor, giving the total calories you burn in a day including exercise and daily movement.
The Mifflin–St Jeor Equation
Women: BMR = 10W + 6.25H − 5A − 161
W = weight (kg) · H = height (cm) · A = age (years)
This formula is recommended by the Academy of Nutrition and Dietetics as the most accurate BMR predictor for the general population. Other formulas (Harris-Benedict, Katch-McArdle) exist but Mifflin–St Jeor has the best accuracy across studies.
Activity Multipliers
| Activity Level | Description | Multiplier |
|---|---|---|
| Sedentary | Desk job, little/no exercise | × 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 | Physical job + daily training | × 1.9 |
Calorie Goals for Different Objectives
- Weight Loss: TDEE minus 500 calories/day → approx. 0.5 kg loss per week (safe rate)
- Maintenance: Eat at TDEE to maintain current weight
- Weight Gain (muscle): TDEE plus 250–500 calories with adequate protein
⚠️ Never go below 1,200 kcal/day (women) or 1,500 kcal/day (men) without medical supervision. Very low calorie diets can cause muscle loss, nutrient deficiencies and metabolic adaptation.
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