TDEE Explained: How Many Calories You Really Need

If you’ve ever wondered “how many calories should I eat?”, the honest answer is: it depends on your TDEE. Total Daily Energy Expenditure is the total number of calories your body burns in 24 hours. Eat below it and you lose weight; eat above it and you gain. Everything else is detail.

The four parts of your TDEE

• BMR (Basal Metabolic Rate): the energy to keep you alive at rest — usually 60–70% of the total.
• TEF (Thermic Effect of Food): the calories used to digest food, around 10%. Protein costs the most to digest.
• NEAT: walking, fidgeting, chores. Hugely variable between people.
• Exercise: deliberate workouts — often smaller than people assume.

How to estimate your TDEE

Start with a BMR formula like Mifflin-St Jeor, then multiply by an activity factor: 1.2 for sedentary, up to around 1.7 for very active. This gives a ballpark. But formulas are averages, and your real number can differ by 200–300 calories in either direction.

The better way: measure it

The most accurate TDEE is your own data. Log your intake consistently for two to three weeks and track your weight. If your weight holds steady, your average daily intake is your maintenance TDEE. This beats any calculator because it reflects your unique metabolism and activity.

A calculator gives you a starting guess. Your bathroom scale, over time, gives you the truth.

Why your TDEE changes

TDEE isn’t fixed. It drops as you lose weight (a smaller body burns fewer calories), rises with muscle mass, and shifts with activity, stress and sleep. This is why a deficit that worked at first may stall later — your target needs updating.

Putting it to use

For fat loss, subtract 15–20% from your TDEE. To gain muscle, add roughly 10%. To maintain, eat at it. Recalculate every four to six weeks or after a noticeable weight change. Logging your meals with a tool like Fotocal makes the “measure it yourself” approach realistic, because tracking becomes fast enough to keep up with.