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constants

constants

Physiological and unit constants, with provenance.

Every number here is a population-level estimate drawn from the literature. They serve two distinct roles, and the distinction matters:

Fixed constants (unit conversions, Atwater factors) are treated as exact.

Prior centers (metabolic rate coefficients, thermic effects, glycogen hydration) are starting points for parameters the filter subsequently estimates from your data. Where a constant is only a prior center, the docstring says so and gives a plausible spread. Do not read any of these as a claim about you specifically.

References are keyed to report/refs.bib.

Attributes

Name	Description
AT_GAIN_PRIOR	Fraction of a sustained energy deficit eventually offset by adaptation.
AT_TAU_DAYS_PRIOR	Time constant of adaptive thermogenesis, in days.
CM_PER_IN	Exact by definition of the international inch.
DEFAULT_PAL	Physical activity level: total expenditure divided by RMR.
ESTIMATED_INTAKE_FRAC_SD	Standard deviation of an estimated day’s energy, as a fraction of it.
FORBES_COEFFICIENT	The constant in Forbes’ relation L = 10.4 ln(F) + C, with masses in kg.
GLYCOGEN_GAIN_PRIOR	Steady-state kg of glycogen complex per (g/day) of carbohydrate deviation.
GLYCOGEN_TAU_DAYS_PRIOR	Time constant of glycogen repletion/depletion, in days.
KCAL_PER_G_FIBER_OVERCOUNT	Correction subtracted per gram of dietary fiber.
KCAL_PER_MJ	1 MJ = 239.006 kcal. Used to convert Hall’s SI-unit coefficients.
KG_PER_LB	Exact by definition of the international pound.
MAX_LOSS_FRAC_PER_WEEK	Default cap on rate of loss, as a fraction of body mass per week.
MIFFLIN_AGE	kcal/day per year of age.
MIFFLIN_HEIGHT	kcal/day per cm of height.
MIFFLIN_WEIGHT	kcal/day per kg of body mass.
MIN_KCAL_FLOOR	Default hard floor on prescribed intake, kcal/day.
MIN_PROTEIN_G_PER_KG	Default floor on prescribed protein, g per kg body mass per day.
PARTITION_KAPPA_PRIOR	Shift in fat fraction per (g/kg/day) of protein above the reference.
PARTITION_MAX	Bounds on the fat fraction of tissue change, for numerical safety.
PROTEIN_REF_G_PER_KG	Reference protein intake, g per kg body mass per day.
RHO_FAT	Energy density of adipose tissue, 39.5 MJ/kg [hall2008].
RHO_GLYCOGEN_COMPLEX	Energy density of the glycogen-plus-bound-water compartment [kcal / kg].
RHO_LEAN	Energy density of fat-free tissue, 7.6 MJ/kg [hall2008].
SCALE_SD_KG_PRIOR	Prior standard deviation of a single morning fasted weigh-in, in kg.
SODIUM_GAIN_PRIOR	Steady-state kg of water per (mg/day) of sodium deviation.
SODIUM_GAIN_PRIOR_LOG_SD	Prior spread of the sodium gain, in log units (see SODIUM_GAIN_PRIOR).
SODIUM_TAU_DAYS_PRIOR	Time constant of sodium-driven water shifts, in days.
TEF_ALCOHOL	Alcohol: 10-20 %, and poorly characterised.
TEF_CARB	Carbohydrate: 5-10 %.
TEF_FAT	Fat: 0-3 %. Dietary fat is stored with very little processing cost.
TEF_PROTEIN	Protein: 20-30 % of ingested energy is spent on its own processing.
WATER_PER_GLYCOGEN	Grams of water retained per gram of stored glycogen.