What TDEE is
TDEE — total daily energy expenditure — is everything your body burns in 24 hours. Most of it is resting energy (BMR): keeping you warm, breathing and thinking. On top come digestion (about a tenth of what you eat) and movement: training, but also walking, standing and fidgeting, which differ between people more than workouts do.
This calculator estimates resting energy with the Mifflin–St Jeor equation, the one reviews found closest for most adults, and multiplies it by an activity factor from 1.2 (mostly sitting) to 1.9 (an athlete or a physical job).
Why the result is only a first guess
Even the best equation is off by 10% or more for about one person in three — easily 200–300 kcal a day. The activity factor is the biggest guess of all: people rarely judge their own activity well, and fitness trackers can be wrong by hundreds of calories too.
The reliable way is to measure: write down what you eat for two to four weeks and weigh yourself several times a week. If your weight trend is flat, what you ate is what you burn. If it falls by about 0.5 kg a week, you burned roughly 550 kcal a day more than you ate. foodoo does this sum for you from your own diary and weigh-ins.
How to use the number
To lose weight steadily, eat about 500 kcal a day less than your TDEE — roughly 0.5 kg a week at first, slowing down as you get lighter. To gain, add 200–300 kcal and plenty of protein. Then watch your weight trend for two weeks and adjust by 100–200 kcal at a time, not more.
Never go below about 1,200 kcal a day without a doctor: it makes it hard to get enough protein, vitamins and minerals.
Questions
- What is the difference between BMR and TDEE?
- BMR (basal metabolic rate) is what your body burns at complete rest. TDEE adds digestion and all movement on top, so it is always higher — usually 1.2 to 1.9 times your BMR.
- How accurate is a TDEE calculator?
- For most adults the Mifflin–St Jeor equation lands within 10% of measured resting energy, but about a third of people fall outside that, and activity is a rough guess. Treat the result as a starting point and correct it with a few weeks of your own food log and weigh-ins.
- Should I eat back the calories my watch says I burned?
- Carefully. Wearables often overestimate exercise energy. The activity level in this calculator already includes your usual training, so adding watch calories on top usually counts them twice.
- How many calories should I eat to lose weight?
- About 500 kcal a day below your TDEE is a common start: roughly 0.5 kg a week. Check your weight trend after two weeks and move by 100–200 kcal if needed, and don't go under about 1,200 kcal a day without medical advice.
Sources
- Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr, 1990.
- Frankenfield D et al. Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc, 2005.
- Hall KD et al. Quantification of the effect of energy imbalance on bodyweight. Lancet, 2011.