TDEE
TDEE, or total daily energy expenditure, is the total number of calories your body spends in a day: resting metabolism, the energy cost of digesting food, deliberate exercise and all incidental movement combined.
TDEE is the number a calorie target is built from. It has four parts, and they are wildly unequal in size.
The four components
Resting metabolic rate is the largest, usually 60 to 70 per cent of the total: the cost of being alive and at rest. It scales mostly with how much you weigh and how much of that is lean tissue.
The thermic effect of food is roughly 10 per cent of intake — the energy spent digesting and storing what you eat. Protein costs the most to process, which is one small reason higher-protein diets are slightly more forgiving.
Exercise is usually the smallest part for most people, often under 10 per cent. An hour in the gym is real, but it is not the bulk of the day.
Incidental movement — walking, standing, fidgeting, carrying things — is the part that varies most between two people of the same size, sometimes by several hundred calories a day.
Why every estimate of it is wrong
Equations predict TDEE from age, sex, weight, height and an activity multiplier. They are fitted to population averages, and individual expenditure scatters around those averages by a few hundred calories in both directions. Treat any calculated TDEE as a hypothesis to test against two weeks of weight data, not a fact.
Sources
- 1.Body Weight Planner — NIDDK, National Institutes of Health
- 2.Dietary Reference Values — European Food Safety Authority
Related reading
- Steps, NEAT, and the calories you burn standing up
Incidental movement varies by hundreds of calories a day, and it falls when you diet. Why a step target is the number you are not tracking.
- Maintenance calories, and how to find yours
The intake that holds your weight steady, measured from three weeks of your own data rather than predicted. Why it is a band, and why it matters most.
- How to calculate your TDEE, and what it can't say
Four components, three equations, and one better method. Why every calculated TDEE is a hypothesis and how to replace it with your own measurement.
- Daily weight lies. The trend does not.
Weigh every morning and read only the seven-day average. Why the daily number is mostly noise, and how to build a trend that tells you what to do next.