NEAT — non-exercise activity thermogenesis — is the energy you spend on everything that is not sleeping, eating or sports-like exercise: walking to work, standing at a counter, typing, yard work, carrying bags, fidgeting1. It matters for calories because it is the most variable part of anyone's day. Two people with the same body and the same training plan can differ by several hundred kcal of daily expenditure, and NEAT is usually where the difference is.
NEAT defined
Daily energy expenditure has four parts: resting metabolism (BMR), the cost of digesting food (TEF), deliberate exercise (EAT) and everything else you do while awake and moving (NEAT). Levine's review, which gave the term its currency, defines NEAT as the energy expended for everything we do that is not sleeping, eating or sports-like exercise, and points out that even trivial physical activities add up — it is the cumulative impact of many small movements that makes up a day's NEAT1.
The line between NEAT and exercise is about intent, not effort. A brisk 40-minute walk to the office is NEAT; the same walk done as a planned workout is exercise. Physiologically the calories are the same. The distinction matters for calculators because the two are asked about separately.
How much of your day it is
The FAO/WHO/UNU expert consultation describes physical activity as the most variable component of daily energy expenditure and, after BMR, the second largest2. Most of that variability is NEAT rather than exercise, simply because NEAT happens for far more hours.
| Component | Typical share of TDEE | How much it varies between people |
|---|---|---|
| BMR | 45–70% | modest — mostly body size and age |
| TEF | ≈ 10% | small — tracks how much you eat |
| Exercise (EAT) | ~5% for most people | large for athletes, small for everyone else |
| NEAT | ~15% in textbook splits | the largest — occupation and habits |
The ~15% is an illustration for a lightly active adult, not a measurement. Levine's review notes that agricultural and manual workers have high NEAT while wealth and industrialisation appear to lower it1 — which is a polite way of saying a desk, a car and a sofa remove most of it. On an expenditure of 2,837 kcal, 15% is about 425 kcal; a person whose day is genuinely on their feet can be spending twice that, and a person who commutes seated and works seated can be spending half.
In plain terms: exercise is the hour you plan; NEAT is the other fifteen hours, and they add up to more.
How our multiplier adjusts for it
Most calculators fold NEAT into a single "activity level" dropdown. Ours asks about it directly, as a second question after training frequency:
| Movement outside training | NEAT adjustment | Multiplier for someone training 4–6× a week | TDEE on an 1,830 kcal BMR |
|---|---|---|---|
| Sedentary — desk, car, sofa | −0.05 | 1.50 | 2,745 kcal |
| Moderate — some walking and standing | 0 | 1.55 | 2,837 kcal |
| Very active — on your feet most of the day | +0.10 | 1.65 | 3,020 kcal |
multiplier = training base + NEAT adjustment. On this BMR the NEAT answer alone spans 275 kcal, which is more than the gap between the common BMR equations. It is a coarse adjustment — three buckets for the most variable thing about you — but a coarse adjustment beats pretending everyone who trains four times a week moves the same amount the other 165 hours.
Answer it by the day you actually have, not the one you intend to have. "Very active" means a job or life spent on your feet — a ward, a site, a shop floor, a farm — not a standing desk.
Why it tends to drop when you diet
Here NEAT stops being a calculator input and becomes a reason your plan needs updating. Physiological studies reviewed by Levine show that NEAT is modulated by energy balance: it increases with overfeeding and decreases with underfeeding1. People in a deficit fidget less, sit more and take the lift without deciding to. Levine goes as far as suggesting that spontaneous physical activity may not be spontaneous at all but programmed.
The consequence for tracking is concrete. A calculator estimate made at the start of a diet assumes the NEAT you had then. Weeks in, some of it has quietly gone, so real expenditure sits below the estimate and the rate of change slows even with perfect logging. This is not a failure of willpower and it is not a metabolism that has shut down — it is a measured behaviour, and an adaptive expenditure model (see how apps estimate energy expenditure) picks it up from your weight trend without you having to notice it. It is also a reason not to plan on a calculator number for months at a time.
This is a description of a measured behaviour, not medical advice. The size of the drop varies from person to person; the mechanism that regulates NEAT is, in Levine's words, unknown.
The short version
NEAT is all the movement that is not training — and for most people it is a bigger slice of the day than training. It is the most variable component of expenditure, our calculator adjusts for it with a −0.05 / 0 / +0.10 change to the multiplier (a 275 kcal spread in our example), and it tends to fall during a deficit, which is one reason expenditure drifts below the starting estimate. Educational overview only — not medical advice.