Sources used directly in calculations
Mifflin–St Jeor resting-energy equation
Used for: Default BMR estimate.
Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. “A new predictive equation for resting energy expenditure in healthy individuals.” American Journal of Clinical Nutrition. 1990;51(2):241–247.
View PubMed record →Comparative equation review
Used for: Rationale for the default equation and uncertainty language.
Frankenfield D, Roth-Yousey L, Compher C. “Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults.” Journal of the American Dietetic Association. 2005.
View PubMed record →Revised Harris–Benedict equation
Used for: Formula-comparison result, not the primary target.
Roza AM, Shizgal HM. “The Harris Benedict equation reevaluated: resting energy requirements and the body cell mass.” American Journal of Clinical Nutrition. 1984;40(1):168–182.
View PubMed record →Katch–McArdle lean-mass equation
Used for: Optional BMR estimate when body fat is supplied.
The commonly used formula is attributed to Katch and McArdle's exercise-physiology texts. Unlike S1–S3, the original derivation is not presented here as a linked peer-reviewed paper. Body-fat measurement error directly affects its output.
Read our implementation note →USDA macronutrient energy factors
Used for: Converting protein and carbohydrate at 4 kcal/g and fat at 9 kcal/g.
USDA Food and Nutrition Information Center explains these general factors. Actual metabolizable energy can vary by food, and labels may not reconcile perfectly after rounding.
Visit USDA FNIC →ACSM walking and running metabolic equations
Used for: Speed-and-grade VO₂ estimates, then gross and net session energy.
The standard walking and running equations are documented in ACSM’s Guidelines for Exercise Testing and Prescription. They estimate steady-state oxygen cost; they do not measure an individual or account for handrail support and changing terrain.
View the publisher’s ACSM Guidelines page →Activity, ranges, goal settings, macros, weekly allocation, and step display
Used for: The planning experience around published equations.
Activity increments, ±8% goal range, deficit/surplus percentages, macro presets, gain-mode bounds, weekly allocation, the session ±20% display band, and inverse step presentation are Calorie Method design choices—not validated clinical instruments. The step result uses user-entered cadence rather than a universal calories-per-step constant.
Review every heuristic →ISSN protein and exercise
Used for: Broad protein context for healthy, exercising adults on the gain page.
Jäger R et al. “International Society of Sports Nutrition Position Stand: protein and exercise.” Journal of the International Society of Sports Nutrition. 2017.
Read the open-access article →ISSN diets and body composition
Used for: Context that diet strategy and energy balance influence body composition.
Aragon AA et al. “International society of sports nutrition position stand: diets and body composition.” Journal of the International Society of Sports Nutrition. 2017.
View the article →Context and validation sources
| ID | Source | How we use it | What it does not prove |
|---|---|---|---|
| S6 | NIDDK Body Weight Planner research | Explains why static calorie arithmetic should not promise exact long-term weight change. | It does not validate our simple trend-calibration equation. |
| S7 | CDC healthy-weight guidance | Supports general language favoring gradual, sustainable change. | Population guidance is not an individual prescription. |
| S8 | Dietary Guidelines for Americans | Provides dietary-pattern context beyond calorie arithmetic. | It does not determine an individual's exact calorie need. |
| S9 | USDA FoodData Central | The food tool links users to select a record and preserves manually entered source IDs and URLs alongside scaled meal values. USDA describes the data as public domain. | No FoodData Central records are embedded or synchronized; Calorie Method does not verify user-entered values. |
| S10 | 2024 Adult Compendium of Physical Activities | Contextualizes METs and activity-energy classification on the calories-burned page. | The calculator uses ACSM equations rather than copying Compendium activity records; a MET does not measure an individual. |
| S15 | Ludlow & Weyand walking-equation comparison | Supports the limitation language that predictive walking equations can materially miss observed metabolic cost. | It does not supply the calculator’s displayed ±20% heuristic or validate every speed and grade. |
| S11 | National Academies Dietary Reference Intakes | Reference framework for future nutrient adequacy content. | Our current macro presets are not DRIs or clinical targets. |
Data provenance rules
- Direct use must be identified. If a source contributes to code, we state which output it affects.
- Context is not validation. A government page that discusses healthy eating does not validate our activity multiplier or macro preset.
- Datasets need versioning. If food or exercise records are added later, each must store source name, record identifier, retrieval date, units, and transformation history.
- Corrections update code and copy together. Formula changes require new fixtures, methodology edits, source-library edits, and a revised review date.
Links and source roles were reviewed August 15, 2026. The project still requires review by a registered dietitian before public production positioning. Source availability and guidance can change.