Total Daily Energy Expenditure (TDEE) is the total number of calories your body burns in a single day. It is the single most important number for anyone serious about changing their body composition — whether the goal is weight loss, muscle gain, or body recomposition. Here's what to know.
TDEE is the sum of four components that determine your total energy burn:
The Mifflin-St Jeor equation is the most accurate formula for estimating BMR in the general population. Published in 1990 by Mifflin et al. in the American Journal of Clinical Nutrition, it was validated against direct calorimetry and found to be within 10% of measured BMR for 85% of the population. It replaced the older Harris-Benedict equation, which tends to overestimate BMR, particularly in overweight individuals.
Mifflin-St Jeor BMR Formula:
Men: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) + 5
Women: BMR = 10 × weight(kg) + 6.25 × height(cm) - 5 × age(y) - 161
Calculate BMR for a 30-year-old man weighing 80 kg at 180 cm:
BMR = 10(80) + 6.25(180) - 5(30) + 5
= 800 + 1,125 - 150 + 5
= 1,780 calories/day
For a 30-year-old woman weighing 65 kg at 165 cm:
BMR = 10(65) + 6.25(165) - 5(30) - 161
= 650 + 1,031.25 - 150 - 161
= 1,370 calories/day
Once you have your BMR, multiply it by an activity factor that reflects your average daily activity level:
| Activity Level | Multiplier | Description |
|---|---|---|
| Sedentary | 1.2 | Desk job, no exercise, minimal walking |
| Lightly active | 1.375 | 1-3 days of light exercise per week, some walking |
| Moderately active | 1.55 | 3-5 days of moderate exercise, active job |
| Very active | 1.725 | 6-7 days of intense exercise, physically demanding job |
| Extremely active | 1.9 | Twice-daily training, professional athlete, heavy labor |
Example: If the 80 kg man above has a BMR of 1,780 and exercises 4 days per week (moderately active), his estimated TDEE is 1,780 × 1.55 = 2,759 calories/day.
Every formula-based TDEE estimate has significant limitations:
The nsuns TDEE spreadsheet, created by Reddit user nsuns and widely used on r/Fitness, is the most practical method for finding your true TDEE. Instead of relying on formulas, it uses real-world data — your daily calorie intake and weight changes — to calculate your actual TDEE through a 3-day weighted moving average.
Why the nsuns method works: Formulas like Mifflin-St Jeor are population averages. The nsuns spreadsheet personalizes TDEE to your specific metabolism. For most people, the spreadsheet reveals a TDEE that differs from their formula estimate by 150-400 calories — which is enough to make or break a diet.
For weight loss, eat 300-500 calories below your TDEE. This produces approximately 0.3-0.5 kg (0.7-1 lb) of fat loss per week. It is important to recalculate your TDEE every 5-10 kg of weight loss, because a lighter body requires fewer calories — what was a moderate deficit at 90 kg may become maintenance or even a surplus at 75 kg.
| Goal | Calorie Adjustment | Expected Weekly Change |
|---|---|---|
| Fat loss (conservative) | TDEE - 300 kcal | -0.3 kg |
| Fat loss (moderate) | TDEE - 500 kcal | -0.5 kg |
| Muscle gain (lean bulk) | TDEE + 200-300 kcal | +0.2-0.3 kg |
| Muscle gain (traditional bulk) | TDEE + 500 kcal | +0.5 kg |
| Recomposition | TDEE - 200-300 kcal | Minimal scale change |
For muscle gain, eat 200-300 calories above your estimated TDEE. This small surplus is enough to support muscle protein synthesis without excessive fat gain. Many people make the mistake of bulking on 500+ calorie surpluses and end up gaining one kilogram of fat for every kilogram of muscle. A lean bulk at +200-300 calories produces a better muscle-to-fat gain ratio and requires a shorter cutting phase afterward.
TDEE is the foundation of any successful body composition change. Start with the Mifflin-St Jeor formula for a baseline estimate, then use daily tracking and the nsuns spreadsheet approach to dial in your personal number. Recalculate regularly and adjust as your weight and activity levels change. Your TDEE is not a static number — it is a dynamic value that requires ongoing attention for best results.
Data sources: Mifflin et al. (1990) AJCN — Mifflin-St Jeor equation validation; Frankenfield et al. (2005) JADA — accuracy of predictive equations; nsuns — TDEE spreadsheet on Reddit r/Fitness; Levine et al. (2006) Science — NEAT and obesity; Hall et al. (2012) Lancet — adaptive thermogenesis and weight loss.