What is TDEE and Why Is It the Most Important Calorie Number?
Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns each day, accounting for everything from breathing (your basal metabolic rate) to exercise, digestion (the thermic effect of food), and non-exercise activity thermogenesis (NEAT — fidgeting, walking, standing). TDEE is the single most important calorie number for body composition goals: eating at TDEE maintains weight, eating below it loses fat, eating above it gains muscle (and fat). Unlike BMR, TDEE gives you a real-world calorie target that reflects your lifestyle. This calculator uses the Mifflin-St Jeor BMR equation — validated as the most accurate for diverse populations — multiplied by an activity factor derived from your weekly exercise habits.
Frequently Asked Questions
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories burned at complete rest — just to keep you alive. TDEE (Total Daily Energy Expenditure) is BMR multiplied by your activity level and adds calories burned through all daily movement, exercise, and digestion. TDEE is always higher than BMR.
How do I choose the right activity level?
Be honest and realistic. "Sedentary" means a desk job with little walking. "Light" means 1–3 gym sessions per week. "Moderate" means 4–5 sessions or an active job. "Very active" is daily intense training. "Extra active" is professional athletes or those with very physically demanding jobs plus training.
Why am I not losing weight at a 500-calorie deficit?
Possible reasons: underestimated calorie intake (food labels can be inaccurate by up to 20%), overestimated activity level, metabolic adaptation (body adjusts after sustained deficits), insufficient protein causing muscle loss, poor sleep affecting hormones, or water retention masking fat loss. Recalculate after 4–6 weeks and adjust based on actual results.