Key Takeaways
- BMR (Basal Metabolic Rate): The baseline calories your body expends at absolute rest just to maintain cellular function and organ vitality.
- TDEE (Total Daily Energy Expenditure): Your BMR multiplied by your physical activity multiplier (exercise, walking, and daily lifestyle).
- Calorie Deficit Formula: To lose 1 lb (0.45 kg) of body fat per week, consume a sustainable 500 calorie deficit below your maintenance TDEE (
TDEE - 500 kcal). - Balancing macronutrients (Protein: 30%, Carbohydrates: 40%, Healthy Fats: 30%) preserves lean muscle mass while maximizing fat loss.
TDEE & Calorie Deficit Calculator
Calculate your exact BMR, maintenance TDEE, weight loss calorie targets, and macro breakdowns in seconds.
If you've ever embarked on a fitness journey, you've likely encountered the universal rule of thermodynamics: Calories In versus Calories Out (CICO). Yet, millions of people struggle with plateaus because they don't know their baseline maintenance numbers.
Your TDEE (Total Daily Energy Expenditure) represents the exact number of calories your body burns in 24 hours. Eating below this number causes fat loss, while eating above it causes weight gain. In this guide, we'll explain the scientific formulas behind BMR and TDEE, how to establish a sustainable calorie deficit, and how to use our Free TDEE & Calorie Deficit Calculator.
The Science: Mifflin-St Jeor BMR Equation
The gold standard mathematical formula for estimating Basal Metabolic Rate (endorsed by the Academy of Nutrition and Dietetics) is the Mifflin-St Jeor Equation:
For Men:
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) + 5
For Women:
BMR = (10 × weight in kg) + (6.25 × height in cm) - (5 × age in years) - 161
Calculating TDEE: Applying the Physical Activity Multiplier
Your body burns energy beyond resting metabolism through digestion (Thermic Effect of Food) and movement (NEAT + structured workouts). Once your BMR is calculated, multiply it by your activity tier:
| Activity Level | Multiplier | Lifestyle Description |
|---|---|---|
| Sedentary | 1.200 | Desk job, little to no structured exercise. |
| Lightly Active | 1.375 | Light workouts or brisk walking 1–3 days per week. |
| Moderately Active | 1.550 | Moderate cardio or weight training 3–5 days per week. |
| Very Active | 1.725 | Hard training or endurance sports 6–7 days per week. |
| Extremely Active | 1.900 | Professional athlete or intense physical labor construction job. |
Setting Your Calorie Deficit for Safe, Steady Fat Loss
One pound of human fat tissue contains roughly 3,500 kcal of stored chemical energy. To achieve healthy fat loss without crashing your thyroid or losing lean muscle:
Mild Weight Loss
0.5 lb / 0.25 kg per week
TDEE - 250 kcal/day. Super easy to sustain, zero hunger pangs.
Standard Weight Loss (Recommended)
1.0 lb / 0.5 kg per week
TDEE - 500 kcal/day. The sweet spot for rapid fat loss and muscle retention.
Extreme Weight Loss
2.0 lb / 1.0 kg per week
TDEE - 1,000 kcal/day. For short-term cuts under medical supervision.
Optimal Macronutrient Split (Protein, Carbs, Fats)
Calories dictate weight change, but macronutrients dictate body composition (fat loss vs muscle loss):
- Protein (30% of Calories / 4 kcal per gram): Prioritize 1.6 to 2.2g of protein per kg of body weight to safeguard muscle and boost satiety.
- Fats (30% of Calories / 9 kcal per gram): Essential for healthy hormone production, joint health, and vitamin absorption (A, D, E, K).
- Carbohydrates (40% of Calories / 4 kcal per gram): Fuels intense resistance training workouts, glycogen replenishment, and mental alertness.
Frequently Asked Questions (FAQs)
Should I ever eat below my calculated BMR?
Generally, no. Eating below your BMR for extended periods triggers metabolic adaptation, lethargy, muscle catabolism, and hormonal disruptions. Keep your deficit between your BMR and TDEE.
How often should I recalculate my TDEE?
Recalculate your TDEE every time you lose 5–10 lbs (2.5–5 kg), because as your body mass decreases, your body burns fewer calories during both rest and movement.
Calculate Your Exact Calories Now
Take the guesswork out of nutrition. Open our Free TDEE & Calorie Deficit Calculator to find your maintenance calories and fat-loss targets today.