TDEE Explained: The Number Behind Your Meal Plan
By Javier · 2026-04-30 · Health & Nutrition
If you have ever tried to plan a diet, lose weight, gain muscle, or just figure out whether you are eating roughly the right amount, you have probably run into a wall called I don't actually know how many calories I should eat. That wall has a name. The number you are missing is your Total Daily Energy Expenditure, or TDEE: the total calories your body burns in a 24-hour day, including being alive, walking from Schuman to your desk, exercising, and digesting food. Until you have a reasonable estimate of this number, every other nutrition decision, from the plat du jour you pick to the box you order on Sunday, is a guess.
TDEE is two things added together
Your TDEE is the sum of your Basal Metabolic Rate (BMR) and your activity expenditure. BMR is what your body burns just to stay alive: heart beating, brain running, body temperature maintained, organs doing what they do. For a 30-year-old, 75 kg, 178 cm person, BMR is roughly 1,600 calories per day. That is the floor. You burn this amount whether you spend the day in bed or running the 20 km de Bruxelles. Activity expenditure is everything on top of that: walking to the metro, climbing the stairs at Porte de Namur, lifting weights, the metabolic cost of digesting food (about 10% of intake). Total of BMR plus activity is your TDEE.
How to calculate BMR
The most widely-validated formula is Mifflin-St Jeor, published in 1990 and still the clinical standard. For men: BMR = (10 × weight in kg) + (6.25 × height in cm) − (5 × age in years) + 5. For women: same formula but ending in − 161 instead of + 5. For our 30-year-old example (75 kg, 178 cm, male): BMR = 750 + 1112.5 − 150 + 5 = 1,717.5 calories per day. There are other formulas (Harris-Benedict, Katch-McArdle), but Mifflin-St Jeor performs best across normal-weight adults and is the safe default.
Then multiply by activity
| Activity level | Multiplier | Description |
|---|
| Sedentary | 1.2 | Desk job, minimal walking, no exercise |
| Lightly active | 1.375 | Desk job, light exercise 1-3x/week |
| Moderately active | 1.55 | Active job or regular exercise 3-5x/week |
| Very active | 1.725 | Hard exercise 6-7x/week |
| Extra active | 1.9 | Manual labor + hard training |
For our 30-year-old example, lightly active (gym twice a week, walks to the office), TDEE = 1,717.5 × 1.375 = 2,361 calories per day. That is the energy intake at which they would stay at their current weight, doing what they currently do.
The activity overestimation trap Most people pick a multiplier one tier too high. A Brussels desk worker who goes to the gym twice a week is lightly active, not moderately active. A Sunday hiker in the Forêt de Soignes who otherwise sits all week is still sedentary or lightly active for TDEE purposes. The multiplier is averaged across all seven days, not anchored on your best ones. And no, a few cobblestone-heavy walks through the Marolles do not bump you a tier. If your weight is not doing what your math says it should, you are probably one tier off.
Calculate yours now
Plug your details in below. The output is your TDEE plus daily-target ranges for losing, maintaining, or gaining weight, with a suggested macro breakdown for each goal.
What to do with the number
TDEE is the maintenance line. Eating at TDEE keeps your weight stable. Below TDEE, you lose weight at roughly the rate the deficit suggests (a 500-calorie daily deficit produces about 0.5 kg of weight loss per week, give or take water fluctuation). Above TDEE, you gain weight, with the composition of that gain depending heavily on whether you are also training. The number is not a target. It is a reference point. You decide what to do with it based on what you are trying to achieve.
From there, two follow-up numbers turn TDEE into an actual plan. The first is your per-meal split: how many calories one meal should have takes this daily figure and divides it across a normal Brussels eating pattern. The second is protein: how much protein a desk job actually needs sits inside the same calorie budget and decides how good those calories make you feel. And if your real constraint is time rather than knowledge, eating well on a 50-hour work week turns the TDEE into three simple anchors.
Once you have your TDEE, our weekly menu (calories listed per dish, in the 480 to 780 range) becomes a tool instead of a guess. You can build a week that lands within 100 calories of any target, no spreadsheet required, and have it delivered across Brussels every Sunday between 14:00 and 18:00. The number on top of the formula is the entire point of doing this exercise.
TDEE: frequently asked questions
What is a normal TDEE for an office worker in Brussels?
For a 30-year-old desk worker who trains once or twice a week, TDEE usually lands between 1,900 and 2,400 calories for men and 1,600 and 2,000 for women. Most Brussels commuters are lightly active (multiplier 1.375), not moderately active, because the office day dominates the week.
How accurate is a TDEE calculator?
A Mifflin-St Jeor estimate is usually within about 10% of reality for normal-weight adults. Treat the number as a starting point: eat at it for two to three weeks, track your weight, and adjust by 100 to 200 calories if the scale is not doing what the math predicted. The activity multiplier is the biggest source of error.
Does my TDEE change in Brussels winter?
Slightly, but not in the way people hope. Cold weather raises energy expenditure only marginally; the bigger seasonal effect is behavioral. In a grey Brussels January you walk less, cycle less and skip the gym more, which lowers your effective activity multiplier and therefore your TDEE. Adjust intake down a touch in the dark months if your activity genuinely drops.
Should I eat back the calories from exercise?
Usually no, if you used an activity multiplier, because exercise is already baked into your TDEE. Eating back the calories your watch reports on top of that double-counts and stalls progress. The exception is a genuinely big day, like the 20 km de Bruxelles, where a separate refuel makes sense.
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