TDEE (estimated daily energy expenditure) helps you know a calorie range for maintenance, fat loss, or weight gain. The Mifflin–St Jeor formula is a common starting point, not absolute truth. Real bodies differ by genetics, how much you stand–walk during the day, sleep, and how accurately you log food. The right use: calculate → eat in that range 2–3 weeks → adjust by weight and measurement trends.
Step 1: Calculate BMR with Mifflin–St Jeor
Use weight (kg), height (cm), age (years):
- Men: BMR ≈ 10×kg + 6.25×cm − 5×age + 5
- Women: BMR ≈ 10×kg + 6.25×cm − 5×age − 161
Example woman 58 kg, 160 cm, 28 years: 10×58 + 6.25×160 − 5×28 − 161 ≈ 580 + 1000 − 140 − 161 ≈ 1,279 kcal (rounded).
BMR is “lying still” energy, estimated. You do not live on BMR unless you are bedridden all day.
Step 2: Multiply by an activity factor (estimated TDEE)
| Level | Factor | Real-world description |
|---|---|---|
| Sedentary | ×1.2 | Lots of sitting, very little training |
| Light | ×1.375 | Train 1–3 sessions/week |
| Moderate | ×1.55 | Train 3–5 sessions, move during the day |
| High | ×1.725 | Physical job or very high training volume |
With the example above, light level: 1,279 × 1.375 ≈ 1,760 kcal/day estimated maintenance. Many office workers training 3 days should start at 1.375 instead of claiming 1.725 — too high a factor makes “maintenance eating that still gains” and then blaming the formula.
Step 3: Set goals from TDEE
- Fat loss: subtract about 300–500 kcal/day (or aim for ~0.25–0.75% body weight/week loss).
- Maintenance: eat around TDEE ±100–150.
- Weight/muscle gain: add 200–400 kcal depending on how easily you store fat.
Prioritize protein around 1.6–2.2 g/kg of goal weight (estimate); split the rest into carbs and fats by Vietnamese taste — rice, vegetables, cooking oil, fish. You do not need to cut an entire group just because of a formula.
Adjust after 3 weeks — the most important part
- Weigh under the same conditions 3–4×/week (e.g. morning after bathroom), use the average.
- Measure waist or take same-angle photos every 2–3 weeks.
- If you want to lose but average weight and waist are flat: subtract another ~100–200 kcal or add walking.
- If weight drops fast >1%/week with fatigue–insomnia: add back 100–200 kcal.
- If you gain too fast while “maintaining”: the activity factor may be higher than reality — trim portions lightly.
Calorie apps and nutrition tables are estimates too. Cooking oil, sweet dipping sauces, and nights out often skew the log. You can eat full and still be in a deficit with high vegetable–protein volume — see eat full while still in a calorie deficit.
What the formula does not know
- Water retention after salty food, menstrual cycle, poor sleep.
- NEAT (walking, standing): hundreds of kcal difference between two people who both “train 3 days.”
- Weekend adherence: two parties can wipe a week’s deficit.
So do not worship 1,760 or any number. The number is a compass; the 3-week trend is the map. Track multiple metrics: progress tracking beyond the scale.
FAQ
1. Do treadmill / wearable burn estimates replace TDEE?
They estimate individual sessions and are often off. Use as a side reference; adjusting by weight–waist trends is more realistic than believing “I burned 600 kcal” absolutely.
2. Recalculate every week?
No. Recalculate when weight changes clearly (e.g. 3–5 kg) or lifestyle shifts (a more standing job). In between, only nudge ±100–200 kcal.
3. Do women and men use different factors beyond BMR?
Activity factors share the same frame; differences are mainly in BMR and often in real NEAT. What still matters is watching the body after 3 weeks.
Formulas and examples are educational — not clinical nutrition advice. People with kidney disease, diabetes, pregnancy, or eating disorders need a professional before deliberately cutting/raising calories.
