Basal Metabolic Rate is the energy your body burns at complete rest just to keep you alive. Multiply BMR by an activity factor and you get Total Daily Energy Expenditure (TDEE) — the calories you actually use each day.

Mifflin–St Jeor (1990) is the modern default and the formula recommended by the American Dietetic Association. Harris–Benedict is older but still widely cited. Katch–McArdle is the most accurate when you know your body fat percentage, because it scales with lean mass.

To lose ~0.5 kg per week, eat 500 kcal less than TDEE. To gain, eat 250–500 kcal more. The calorie goal table converts these rules into daily numbers.