Every nutrition goal — losing fat, building muscle, or maintaining weight — comes down to energy balance. Your Basal Metabolic Rate (BMR) is the calories your body burns at complete rest just to keep organs functioning, regulate temperature, and sustain basic cellular processes.
It typically accounts for 60–75% of total daily expenditure and varies with age, sex, height, weight, and lean muscle mass.
Total Daily Energy Expenditure (TDEE) adds everything on top of BMR: digestion, daily movement, exercise, and non-exercise activity like walking, fidgeting, and standing. The Mifflin-St Jeor equation is the most widely validated BMR formula: for men, BMR = 10 × weight(kg) + 6.25 × height(cm) − 5 × age + 5; for women, substitute −161 for +5. Multiply BMR by an activity factor (1.2 for sedentary, 1.55 for moderately active, 1.725 for very active) to estimate TDEE.
These numbers are starting points, not gospel. Individual metabolism varies by 10–15% even among people with identical stats. Track your weight and intake for three to four weeks, then adjust calories up or down by 150–200 based on real results. Understanding your energy budget turns nutrition from guesswork into a system you can tune — whether your goal is a moderate deficit for fat loss, a slight surplus for muscle gain, or maintenance that fuels performance without drift.
