The activity factor, also called PAL (physical activity level), is the number a calculator multiplies your basal metabolic rate by to estimate your total daily energy expenditure (TDEE). It packs everyday movement, training and digestion into a single number.
The usual levels
Common approximations, as also used by the TDEE calculator:
- 1.2: little movement, desk job, no training
- 1.375: lightly active, 1 to 3 training sessions per week
- 1.55: moderately active, 3 to 5 training sessions per week
- 1.725: very active, 6 to 7 training sessions per week
- 1.9: extremely active, physical work plus training
Example: With a BMR of 1,800 kcal, a factor of 1.375 gives about 2,475 kcal, a factor of 1.55 about 2,790 kcal. One level makes a difference of just over 300 kcal here. These numbers are a worked example.
The biggest uncertainty in the calculator
Hardly anyone knows which level really fits. Many people overestimate their activity, especially with a desk job, because a few training sessions a week do little to change the fact that you sit for the rest of the day. When in doubt, pick the lower level.
If you chose a fitting factor, do not eat back the training calories from your fitness watch. Your training is already included.
Check the factor against your trend
What matters is not the factor but what your trend weight shows over the following weeks. Eat the estimated amount for two to three weeks. If the trend stays flat, the choice was good. If it rises or falls, adjust your calories directly instead of fiddling with the factor.