Calories Burned: How to Read MET Values (and Their Limits)

MET stands for Metabolic Equivalent of Task. One MET is defined as the energy you use sitting quietly — approximately 3.5 millilitres of oxygen per kilogram of body weight per minute, which works out at roughly 1 kcal per kilogram per hour.

Every activity is then expressed as a multiple. An activity rated at 8 METs costs about eight times your resting rate. Running at 10 km/h is around 9.8 METs; walking briskly is around 5.5; yoga is around 2.5.

These values come from the Compendium of Physical Activities, a reference compiled from measured oxygen consumption across hundreds of activities and periodically updated. It is the standard source, and it is what the Calories Burned Calculator uses.

The standard formula is kcal per minute = (MET × 3.5 × body weight in kg) ÷ 200. Multiply by duration for the session total.

For a 70 kg person running at 9.8 METs for 30 minutes: (9.8 × 3.5 × 70) ÷ 200 = 12 kcal per minute, or about 360 kcal for the session.

Notice that body weight is in the numerator. This is why heavier people burn more doing identical work — there is simply more mass to move, and the energy cost scales with it. It is also why calorie burn falls as you lose weight, even doing exactly the same workout.

Having a rough sense of the scale is more useful than memorising figures.

Fitness trackers routinely report different figures from MET-based calculations, sometimes by 30% or more, and neither is authoritative.

Trackers combine heart rate, accelerometer data and proprietary algorithms, often with personal calibration. In principle this can capture individual effort better than a lookup table. In practice, validation studies have repeatedly found consumer devices carry substantial error for energy expenditure — commonly 20–30%, and worse for resistance training and irregular activities.

MET values have their own error: they are population averages that ignore individual efficiency, fitness and technique. A trained runner uses less energy than a novice at the same pace.

The honest position is that all of these numbers are estimates with meaningful error bars, and treating any of them as precise is the mistake.

This is the most consequential practical error in the whole area. Most people set calorie targets using a TDEE estimate that includes an activity multiplier — and that multiplier already accounts for their regular training.

Adding tracked exercise calories on top of an activity-adjusted TDEE counts the same workout twice, and it is the single most common reason an intended deficit quietly disappears. Combined with the fact that burn estimates tend to run high, a 400 kcal 'earned' snack can comfortably exceed the actual expenditure.

The fix is to choose one method. Either use a sedentary multiplier and add tracked exercise, or use an activity-adjusted multiplier and do not. The Calorie Calculator assumes the latter.

MET values describe the total energy cost during an activity, including the resting metabolism that would have been running anyway. For a strict 'extra calories burned' figure you would subtract your resting expenditure for that duration.

For vigorous activity this correction is small — at 10 METs, the resting portion is a tenth of the total. For light activity it is proportionally large: at 2 METs, half the reported burn is what you would have spent sitting still.

This is one reason low-intensity activity looks better on a tracker than it deserves, and another reason not to treat these numbers as an entitlement to eat.

Excess post-exercise oxygen consumption — EPOC, or 'afterburn' — is the elevated metabolic rate that persists after exercise as your body restores itself to baseline. It is real, and it is much smaller than marketing suggests.

For most sessions EPOC accounts for something in the range of 6–15% of the energy burned during the exercise itself. It is larger after high-intensity and heavy resistance work than after steady-state cardio, which is the grain of truth behind the claims.

A 300 kcal session might therefore carry another 20–45 kcal of afterburn. Worth knowing, not worth planning around.

Exercise is worth doing for many reasons, but as a calorie lever it is weaker than intuition suggests. A hard 45-minute session might cost 400 kcal — recoverable from a single pastry, and less than a modest daily dietary adjustment sustained across a week.

There is also evidence of compensation: after exercise, many people unconsciously move less for the rest of the day and eat somewhat more, which offsets part of the burn. The size of this effect varies a lot between individuals, but it is rarely zero.

None of that argues against training. It argues for the right framing: exercise is the best available intervention for fitness, muscle, mood, and long-term health, and a comparatively blunt instrument for calorie balance. Diet does the heavier lifting there.

Use calorie-burn estimates for comparison rather than accounting. They are good at telling you that running costs roughly twice what brisk walking does, and poor at telling you exactly how many calories today's session was worth.

For weight management, the reliable signal is your weekly average body weight over three weeks against a consistent intake, not the sum of your tracked workouts. Exercise contributes, but for most people it contributes less to the calorie equation and more to health, fitness and muscle retention.

That reframing is useful. Train because it makes you healthier and stronger; manage weight primarily through what you eat.