Calorie Needs Explained: BMR, TDEE, and Your Daily Calories

Whether you want to lose fat, maintain your weight, or build muscle, it all starts with one number: how many calories your body needs each day. This guide explains where that number comes from and how to turn it into a sensible target.

BMR — the calories you burn at rest

Your Basal Metabolic Rate (BMR) is the energy your body uses just to stay alive — breathing, circulating blood, keeping your organs running — if you did nothing all day. It is usually estimated with the Mifflin-St Jeor formula, which uses your age, sex, height, and weight. BMR is the biggest single chunk of your daily calorie burn.

TDEE — your real daily need

You obviously do more than lie still, so your actual need is higher than BMR. Total Daily Energy Expenditure (TDEE) is your BMR multiplied by an activity factor — a number that reflects how active you are, from sedentary (little exercise) up to very active (hard training or a physical job). TDEE is the number of calories that would keep your weight stable.

Setting a target

• To maintain weight, eat around your TDEE.
• To lose weight, eat below it — a deficit of about 500 calories a day is roughly 0.5 kg of fat loss per week.
• To gain weight or build muscle, eat above it — a modest surplus of 250–500 calories a day supports steady gains.

Why it is an estimate

These formulas are population averages, so your true burn can be a few hundred calories higher or lower. The practical approach is to use the estimate as a starting point, track your weight over two or three weeks, and adjust your intake up or down based on what actually happens on the scale.

To estimate your own BMR and daily calorie target, use our Calorie Calculator — enter your details and activity level to see your maintenance calories along with suggested targets for losing or gaining weight.