TDEE Explained: How Many Calories You Actually Burn

If you’ve ever wondered why one friend can eat what looks like double your dinner and stay lean, part of the answer often comes down to a single number: their TDEE. It’s the calorie figure most diets skip straight past, and yet it’s the one that shapes whether you lose weight, stay the same, or slowly creep up.

Get it roughly right and everything else - your calorie target, your protein goal, your rate of loss - falls into place. Get it wrong and you’ll either feel starved or wonder why the scale won’t move. Here’s how it actually works, without the maths degree.

What TDEE actually means

TDEE stands for Total Daily Energy Expenditure. In plain terms, it’s the total number of calories your body burns in a full day, including everything from breathing to walking to the gym to digesting your lunch.

It’s built from four parts:

• BMR (Basal Metabolic Rate) - the energy your body uses just to keep you alive: heart beating, lungs working, brain running. This is the biggest slice, often around 60–70% of the total for many people.
• NEAT (Non-Exercise Activity Thermogenesis) - fidgeting, walking to the shop, standing, carrying bags, chasing kids. This varies widely between people and helps explain a lot of that “lucky metabolism” impression.
• TEF (Thermic Effect of Food) - the calories burned digesting what you eat, roughly 10% of your intake on a typical mixed diet. Protein costs the most to process, which is one reason higher-protein diets can help.
• Exercise - deliberate training. For most people this is a smaller piece than they’d guess, often something like 5–15% of the day depending on how much they train.

Your body is not a calculator. TDEE is an estimate, not a fixed law - it shifts with your weight, activity, sleep, and even the temperature. Treat any number you get as a starting point, then adjust based on what the scale does over two to three weeks.

How to estimate your number

You don’t need a lab. A quick two-step method gets most people close enough.

Step 1: Estimate your BMR. The Mifflin-St Jeor equation is one that many dietitians use. For a rough version:

• Men: (10 × weight in kg) + (6.25 × height in cm) - (5 × age) + 5
• Women: (10 × weight in kg) + (6.25 × height in cm) - (5 × age) - 161

Step 2: Multiply by an activity factor to account for movement:

• Mostly sitting, little exercise: BMR × 1.2
• Light activity, 1–3 sessions a week: BMR × 1.375
• Moderate, 3–5 sessions: BMR × 1.55
• Very active, 6–7 sessions or a physical job: BMR × 1.725

So a 35-year-old woman, 70 kg, 165 cm, moderately active lands around: BMR ≈ 1,412, then × 1.55 ≈ 2,190 calories a day. That’s her rough maintenance estimate, not a precise figure.

If the sums make your eyes glaze over, a tracker app will do all of this the moment you enter your details, and update it as your weight changes.

Turning TDEE into a real goal

Once you have your maintenance number, the rest is fairly simple arithmetic:

• Fat loss: eat roughly 300–500 calories below TDEE. That tends to produce around 0.25–0.5 kg of loss per week, which is a pace many people can actually sustain.
• Maintenance: eat at your TDEE. Handy after a diet, or when you’re happy where you are.
• Muscle gain: eat around 200–300 calories above TDEE, paired with resistance training and enough protein.

A gentle deficit tends to work better than an aggressive one for most people. Cut too hard and you’re more likely to lose muscle, feel miserable, and rebound. The NHS suggests a steady loss of around 0.5 to 1 kg a week as a safe and realistic target for most adults.

Why the number keeps changing

This is the part people miss. Your TDEE isn’t static.

1. You lose weight, so it usually drops. A lighter body generally burns fewer calories. The deficit that worked at 90 kg often won’t work the same at 80 kg, which is one reason plateaus happen.
2. NEAT can quietly fall. When dieting, many people unconsciously move less - fewer fidgets, slower walks - as the body tends to conserve energy.
3. More muscle can nudge it up a little. Resistance training and adequate protein help protect the lean tissue you already have, though the direct calorie effect of added muscle is modest.

The fix isn’t to slash calories again the moment progress stalls. Recalculate every few kilos, add a bit more daily movement, and keep protein high enough to help hold onto muscle.

Making it work day to day

Here’s the honest bit: the equations get you a ballpark, but your own results are the real feedback. Log your food fairly consistently for two to three weeks, keep an eye on your average weight (not a single morning’s reading), and compare.

• Losing faster than about 1 kg a week and feeling drained? Consider adding 100–200 calories back.
• Not moving at all after three weeks? Trim 150–200, or find more daily steps.
• Weight bouncing around? That’s usually water and food volume, not fat. Watch the weekly trend.

A photo-scanning tracker can take some friction out of this. Snap the plate, get a calorie and macro estimate, and let the app hold your running total against your TDEE-based goal. Bear in mind these estimates can be off, so use them as a guide rather than gospel. You’re not aiming for perfection - you’re aiming for a number that’s roughly right, most days.

This article is for general information and isn’t medical advice. If you have a health condition or take medication, check with your GP or a registered dietitian before making big changes to your diet.