What is a MET?
One MET (Metabolic Equivalent) is the energy you burn sitting still — about 1 kcal per kg of body weight per hour. Multiply MET × weight (kg) × hours = total calories. Walking at 5 km/h is 3.5 MET; running at 10 km/h is ~10 MET. The Compendium of Physical Activities lists METs for hundreds of activities, validated against direct oxygen-consumption measurements in lab settings.
Why fitness trackers overestimate
Wrist-based heart-rate trackers consistently overestimate calorie burn — by 30–80% in strength training and HIIT, and 20–40% in steady-state cardio (Shcherbina et al., J Pers Med 2017). MET-based calculations are simpler and tend to be more accurate for typical activities. Use both as rough guides — neither is gospel.
How to use this number
Don't add this back into your daily calories as a license to eat more — most people overestimate burn and underestimate intake, which is why “I worked out so I earned this” doesn't move the scale. Instead, use exercise calories as bonus, not budget. If fat loss is the goal, set your intake target from TDEE minus 15–20% and treat exercise as cardiovascular and metabolic medicine — not a credit card.
Caveats on accuracy
MET values assume average mechanical efficiency. A fit person running at 10 km/h burns slightly less than an unfit person at the same speed (better economy). Body composition also matters — two people of the same weight burn slightly different amounts depending on how much of that weight is lean mass. Treat any single calorie number as ±20%.
References
- Ainsworth BE et al. 2011 Compendium of Physical Activities. Med Sci Sports Exerc. 2011;43(8):1575-1581.
- Shcherbina A et al. Accuracy in wrist-worn, sensor-based measurements of heart rate and energy expenditure. J Pers Med. 2017;7(2):3.