TDEE Calculator for Over 40s: Why Your Calorie Needs Change

From age 40 onwards, many adults experience a gradual decline in resting metabolic rate (around 5% per decade), a decrease in muscle mass, and hormonal shifts including lower testosterone in men and approaching perimenopause in women. These changes mean your TDEE at 45 is likely lower than it was at 30. Recalibrating your calorie intake to match your current biology is key to maintaining a healthy weight and body composition.