How the calculation works
First calculate resting energy expenditure with Mifflin–St Jeor, then multiply it by the chosen activity factor. These conventional factors range from 1.2 for sedentary activity to 1.9 for exceptionally high activity.
Worked example
If an estimated BMR is 1,500 kcal/day and the chosen activity factor is 1.55, estimated TDEE is 2,325 kcal/day.
Understanding the result
Maintenance calorie estimates are useful starting points for planning meals or discussing a nutrition plan. They are not exact measurements of metabolism or physical activity.
Watch actual changes over time, rather than treating the first estimate as a fixed prescription. Needs may change with illness, weight change, training volume, and other circumstances.
Limitations
For nonpregnant adults as a general educational estimate. Activity categories are approximate and not clinically validated for every population.