Total Daily Energy Expenditure (TDEE) refers to the total number of calories your body uses in a day. It includes the energy burned through basic bodily functions, known as Basal Metabolic Rate (BMR), as well as the calories expended during physical activities and the energy used for digestion. TDEE can vary based on factors such as age, gender, weight, and activity level. Understanding your TDEE is important for managing weight, as it helps determine how many calories you should consume to maintain, lose, or gain weight effectively.