Total Daily Energy Expenditure (TDEE)

The Mifflin-St Jeor Equation

Introduced in 1990, the Mifflin-St Jeor equation is considered the most accurate formula for calculating Basal Metabolic Rate (BMR) in modern populations, outperforming the older Harris-Benedict equation.

BMR vs TDEE

• BMR (Basal Metabolic Rate): The absolute minimum number of calories your body requires to keep you alive if you were in a coma.
• TDEE: Your BMR multiplied by an activity multiplier. This represents the total calories you burn in a typical day.

Clinical Application (Weight Loss)

The First Law of Thermodynamics applies to human metabolism. To lose weight, you must consume fewer calories than your TDEE. A standard clinical recommendation is a deficit of 500 kcal per day, which theoretically yields a weight loss of 1 lb per week (since 1 lb of adipose tissue contains approximately 3,500 kcal).

Note: Metabolic adaptation occurs during weight loss; recalculate your TDEE for every 5kg of weight lost.