Basal Metabolic Rate (BMR) is the baseline number of calories your body burns purely to keep you alive in a resting state (breathing, cellular repair, organ function). Total Daily Energy Expenditure (TDEE) adds the energy needed for physical movement, exercise, and the thermic effect of food. TDEE is your true daily maintenance intake.

Extensive clinical trials by the Academy of Nutrition and Dietetics have demonstrated that the Mifflin-St Jeor formula is within 10% of measured resting metabolic rate for the vast majority of non-obese and obese individuals, whereas older Harris-Benedict formulas tend to overestimate caloric needs by 5% or more.

One pound of human adipose body fat stores roughly 3,500 kilocalories of energy. Creating a daily caloric deficit of 500 calories below your TDEE produces a weekly deficit of 3,500 kcal, yielding approximately 1 pound (0.45 kg to 0.5 kg) of fat loss per week safely and sustainably.

Protein and carbohydrates yield approximately 4 kilocalories per gram, while dietary fats provide 9 kilocalories per gram. The calculator applies clinical balance guidelines (30% protein for muscle preservation, 40% carbs for athletic glycogen, 30% healthy fats for hormone production) to translate your daily calorie target directly into gram quantities.