The 2,000 calories you see on food packaging is a population average — not your number. Your actual daily calorie need depends on your body size, age and how much you move. Getting it right is the foundation of any goal, whether that's losing fat, building muscle or just maintaining your current weight.
TDEE (Total Daily Energy Expenditure) is the total number of calories your body burns in a day — including everything from keeping your heart beating to your gym session. It's calculated in two steps:
Step 1 — BMR (Basal Metabolic Rate): The calories you burn at complete rest. Calculated using the Mifflin-St Jeor equation, which accounts for your weight, height, age and sex. For a 35-year-old woman, 70kg, 165cm: BMR = (10 × 70) + (6.25 × 165) − (5 × 35) − 161 = approximately 1,497 kcal/day.
Step 2 — Activity multiplier: Multiply your BMR by a factor based on how active you are day-to-day.
| Activity level | Multiplier | Description |
|---|---|---|
| Sedentary | × 1.2 | Desk job, little or no exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days/week |
| Moderately active | × 1.55 | Moderate exercise 3–5 days/week |
| Very active | × 1.725 | Hard exercise 6–7 days/week |
| Extremely active | × 1.9 | Physical job + hard training daily |
To lose fat: Eat 300–500 kcal below your TDEE. A 500 kcal daily deficit produces roughly 0.5kg of fat loss per week (since 1kg of fat ≈ 7,700 kcal). Deficits above 1,000 kcal/day risk muscle loss and metabolic adaptation — the body becomes more efficient and burns less, slowing progress.
To maintain weight: Eat at your TDEE. Track for 2–3 weeks and adjust based on actual weight changes — TDEE is an estimate, not an exact number.
To build muscle: Eat 200–300 kcal above your TDEE (a lean bulk). Larger surpluses lead to more fat gain alongside muscle. Protein intake matters as much as total calories — aim for 1.6–2.2g per kg of bodyweight.
As you lose weight, your BMR decreases because you're carrying less mass — your body simply needs fewer calories to function. A person who weighed 90kg and now weighs 75kg has a meaningfully lower BMR. This is why recalculating your TDEE every 4–6 weeks as your weight changes is important — otherwise you're using an outdated target.
Age also matters. BMR tends to decline by around 1–2% per decade after age 30, partly due to natural muscle loss (sarcopenia). Maintaining muscle through resistance training slows this decline and keeps your TDEE higher as you age.
Eat below your TDEE. A deficit of 500 kcal/day produces roughly 0.5kg of fat loss per week. Most guidelines recommend not going below 1,200 kcal/day for women or 1,500 kcal/day for men without medical supervision, as very low intakes risk muscle loss and nutritional deficiencies.
For most adults, 1,200 kcal/day is below the minimum recommended intake. It can be appropriate for short periods under medical supervision, but sustained low-calorie diets cause muscle loss, slow metabolism and are difficult to maintain. A moderate deficit of 300–500 kcal below TDEE is more sustainable and produces better long-term results.
The most common reason is inaccurate tracking — most people underestimate portions by 20–40%. Other factors include metabolic adaptation (your body burns fewer calories in response to restriction), water retention masking fat loss on the scale, and eating back more exercise calories than you burned. Weigh food for 2 weeks and track everything honestly before concluding the deficit isn't working.
Yes — but less than most people think. The activity multiplier in TDEE calculations accounts for your overall lifestyle activity level. If you add more exercise, your TDEE increases, meaning you need to eat more to maintain weight, or the deficit naturally increases. Most people overestimate how much exercise burns — a 5km run burns roughly 300–400 kcal, not 800.
BMR (Basal Metabolic Rate) is the calories you'd burn lying completely still all day — the minimum energy to keep your organs functioning. TDEE is your actual daily calorie burn including all movement and activity. For most people TDEE is 1.3–1.7 times their BMR. BMR is the starting point; TDEE is the number you use for dietary planning.