UNDERSTAND THE METHOD
Describe your usual week
Think about movement during work, travel, home tasks, and planned exercise. A single exercise session does not stand for all waking hours. If your weekdays and weekends differ, describe both before choosing a category. Choose the category that best fits the whole week, then record the category name. If your schedule changes for a season or a new job, the old assumption may no longer describe you.
Read the model's labels
Activity categories belong to a specific energy model. The National Academies report uses physical-activity categories in its estimated energy requirement equations and states that activity is a variable part of total expenditure. Another calculator may use multipliers with similar names but different definitions. Do not copy a category from one tool into another without reading its meaning. Compare the model notes when results differ.
Use a comparison when unsure
Run two adjacent categories with the same age, height, and weight. The difference shows how strongly the selected assumption affects the model. It does not tell you which category is true. Keep both results labeled. A result may change because the model changed or because your input changed. A useful saved record shows the date, category, formula, and inputs.
Treat the output as provisional
The 2023 National Academies equations were developed from measured expenditure data, yet the report still shows individual prediction error. Use a calculated value as a starting estimate. If you collect repeated observations, compare them under similar conditions and reassess the assumption when your routine changes. The energy calculator includes activity in its selected equation. Adding exercise calories again can count the same activity twice.
Common questions
Does one hard workout make me very active?
No. Choose a category for your usual whole week, including non-exercise hours.
Should I add exercise calories afterward?
Check the model first. A total daily energy estimate normally includes activity.
What if I am between categories?
Compare both with the same inputs and keep the assumptions beside the results.
Sources & limitations
Sources checked September 12, 2026. These notes explain published methods. They have not received an independent clinical review.
- The 2023 energy equations use activity categories and recognize physical activity as a variable part of TDEE.nationalacademies.org
- The report gives individual prediction error, so category selection does not make a result exact.nationalacademies.org
- NIDDK's planning model includes physical activity and calorie assumptions that may change over time.niddk.nih.gov