Components of TDEE
Your body burns calories through four main pathways:
BMR (60-70%): Basal Metabolic Rate. Breathing, circulation, cell production. This is what you'd burn lying in bed all day. It's the largest chunk by far.
Exercise Activity (5-10%): Intentional exercise—running, lifting, sports. Despite feeling significant, it's a small percentage of total burn for most people.
NEAT (15-30%): Non-Exercise Activity Thermogenesis. Walking to the car, fidgeting, standing, taking stairs. This varies enormously between individuals and is often the biggest difference between "fast" and "slow" metabolisms.
TEF (8-15%): Thermic Effect of Food. Digesting food burns calories. Protein has the highest thermic effect (~20-30%), followed by carbs (~5-10%), then fat (~0-3%).
The Mifflin-St Jeor Equation
Males: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age + 5
Females: BMR = 10×weight(kg) + 6.25×height(cm) − 5×age − 161
TDEE = BMR × Activity Multiplier
TDEE for Weight Goals
| Goal | Calorie Target | Expected Rate |
|---|---|---|
| Aggressive Cut | TDEE − 750 | ~1.5 lb/week loss |
| Moderate Cut | TDEE − 500 | ~1 lb/week loss |
| Slow Cut | TDEE − 250 | ~0.5 lb/week loss |
| Maintenance | TDEE | Weight stable |
| Lean Bulk | TDEE + 250 | ~0.5 lb/week gain |
| Bulk | TDEE + 500 | ~1 lb/week gain |
Why Your TDEE Might Be Wrong
Three common reasons. First, activity level overestimation—most people select one level too high. Working out 3 times a week with a desk job is "lightly active," not "moderately active." Second, metabolic adaptation—after prolonged dieting, your BMR drops as the body conserves energy. Third, individual variation—genetics, thyroid function, and NEAT differences can shift TDEE by 200-300 calories in either direction.
Use the calculated TDEE as a starting point. Track weight for 2 weeks. Adjust by 100-200 calories based on results.