About Daily Calorie Needs (TDEE)
Total Daily Energy Expenditure (TDEE) is the total number of calories you burn in a single day. It includes your BMR plus the energy used for physical activity (exercise and daily movement) and the thermal effect of food. Knowing this number is the foundation of any weight gain or loss plan.
Scientific Basis
TDEE = BMR x Activity Factor. The activity factors (originally derived from the Katch-McArdle multipliers) range from 1.2 (Sedentary) to 1.9 (Extra Active). This model assumes a linear relationship between reported activity levels and energy output.
Health Implications
Matching your intake to your TDEE maintains your current weight. Creating a mismatch drives change:
- Deficit: Eating below TDEE forces the body to use stored energy (fat/muscle).
- Surplus: Eating above TDEE provides excess energy, stored as fat or used to build muscle (if training).
Actionable Tips
Move More (NEAT): Non-Exercise Activity Thermogenesis (walking, standing, fidgeting) can differ by up to 2000 kcal between people.
Be Honest: Most people overestimate their activity level. If in doubt, choose the lower activity setting.
Monitor Trends: Use the calculator as a starting point, then adjust based on your actual weight change over 2 weeks.
Limitations
Self-reported activity is subjective. 'Moderate exercise' to one person might be 'Light' to another. Adaptive changes in NEAT can also offset exercise calories.