NEAT Calories: The Energy You Don't Count

Total daily energy expenditure is the sum of four parts: basal metabolic rate, the thermic effect of food, deliberate exercise, and non-exercise activity thermogenesis. NEAT is everything that is not sleeping, not digesting, and not a workout: standing, walking to the kitchen, gesturing while talking, maintaining posture, fidgeting. It is the component with the widest between-person spread and the one most often left out of a calculation.

The four components, and where NEAT sits

A common decomposition, used in doubly labelled water work and in the Levine laboratory’s reviews of activity thermogenesis, splits daily expenditure like this:

The ranges are wide because the fourth row is wide. Two adults of the same height, weight and body composition can differ by several hundred kilocalories per day in NEAT alone. That spread is not a rounding error; it is often larger than the difference produced by a structured exercise programme.

How many calories do I burn a day?

Start with a resting estimate. The Mifflin-St Jeor equation is the usual choice for adults:

men:   BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age + 5
women: BMR = 10 x weight(kg) + 6.25 x height(cm) - 5 x age - 161

Worked example for a 40-year-old woman, 165 cm, 70 kg:

BMR = 10 x 70 + 6.25 x 165 - 5 x 40 - 161
    = 700 + 1031.25 - 200 - 161
    = 1370 kcal/day

That is basal. To reach total daily energy expenditure, multiply by an activity factor. Published factors run from about 1.2 for sedentary to 1.9 for very active, but the factor is a population average and hides the NEAT spread. A more honest presentation is a band:

low  NEAT: 1370 x 1.3 = 1781 kcal/day
mid  NEAT: 1370 x 1.5 = 2055 kcal/day
high NEAT: 1370 x 1.7 = 2329 kcal/day

The 1.3 to 1.7 range is not a personality description. It reflects occupation, whether the person stands or sits, how much they walk without calling it walking, and how much they fidget. The midpoint is a guess; the band is the information.

Calories burned doing nothing

“Doing nothing” is not zero. Lying still, awake, still costs roughly the basal rate. Sitting adds a small amount above lying; standing adds more. The increments are modest per hour but accumulate:

• Lying quietly: approximately BMR
• Sitting: BMR plus a small increment, often cited around 5-10% above lying
• Standing: roughly 10-20% above sitting in some measurements
• Fidgeting while seated: variable, and the source of much of the individual spread

A person who stands for three extra hours a day instead of sitting may add on the order of 50-100 kcal/day, depending on body size and how much they shift weight. That is not dramatic per day. Over a year it is a meaningful difference in energy balance, and it is exactly the kind of movement that never appears in an exercise log.

Fidgeting calories

Fidgeting is the clearest example of NEAT that people dismiss. In controlled studies, some participants show large increases in spontaneous movement when overfed, and others show almost none. The ones who move more tend to store less of the surplus. The mechanism is not mysterious: muscle contraction costs ATP, ATP is regenerated from fuel, and the fuel comes from the diet or from stores.

The practical point is that fidgeting is not a strategy. Telling someone to fidget is like telling them to have a different personality. It is useful instead as an explanation: part of why two people eat similarly and diverge is that one of them is in motion more, without either of them noticing.

NEAT falls in a deficit

This is the part that matters most for anyone tracking intake. During an energy deficit, NEAT tends to fall. People sit more, stand less, walk slower, gesture less, take fewer spontaneous steps. The change is usually not deliberate and often not noticed.

The fall has two sources. The first is mass: a smaller body costs less to move, so the same movement burns fewer calories. The second is behavioural: the spontaneous movement itself decreases. The second is the larger and more surprising one.

A worked model, using the same woman, after a 5 kg loss:

new weight: 65 kg
BMR = 10 x 65 + 6.25 x 165 - 5 x 40 - 161
    = 650 + 1031.25 - 200 - 161
    = 1320 kcal/day

If NEAT also drops from a high factor to a mid factor:

before: 1370 x 1.7 = 2329 kcal/day
 after: 1320 x 1.5 = 1980 kcal/day

That is a fall of about 349 kcal/day, and only part of it is the 5 kg. The rest is the activity factor moving. This is why a deficit that worked at the start can stop working without any change in reported intake. The line is not straight; maintenance falls as mass falls, and NEAT falls with it.

What people get wrong

The common mistake is to treat NEAT as a fixed multiplier. Someone calculates maintenance once, at the start, and then wonders why the same intake no longer produces the same result. The error is natural because the activity factor is presented as a constant in most equations, and because the change in NEAT is invisible. Nobody feels themselves standing less.

The second mistake is to attribute the whole fall to “slowed metabolism.” Basal metabolic rate does fall with mass, but the NEAT component often accounts for a comparable or larger share of the drop, and it is the part that can be influenced by behaviour, at least partially. The third mistake is to try to outrun the fall with more exercise. Exercise adds to the exercise component, but it can also displace NEAT: a hard session may leave someone more sedentary for the rest of the day, and the net change can be smaller than the workout’s nominal cost.

What to do with the number

Use the band, not the midpoint. If maintenance is estimated at 2,300 kcal/day with a 10% standard error, the working range is roughly 2,070-2,530. Plan against the low end if the goal is a deficit, and expect the low end to move down as mass falls. Recalculate after every few kilograms, and treat any single day’s figure as a sample from a distribution rather than a measurement.

NEAT is the largest uncontrolled term in the equation. It is also the one most likely to change without being recorded. A page that gives a single number for it is giving a midpoint and calling it a fact.

This is general information about energy arithmetic, not medical advice. If eating or activity is causing distress, or if weight is changing without explanation, a clinician is the right route. In the US, the National Eating Disorders Association helpline is available at 1-800-931-2237; in the UK, Beat’s helpline is 0808 801 0677.