Body Fat % (BMI-based, Deurenberg)

Inspectable records

Ledger state

The current ledger marks this instrument verified clean within the source-bound verification corpus.

Area

Biology, Medicine & Pharmacology

Tranche

tranche-2

Evidence ID

t2-050

Ledger rows

1

No ledger note is attached.

Review findings

The arithmetic formula is correct for the adult Deurenberg equation, and the honest label is appropriate. Final catalog approval requires explicitly documenting sex encoding and the adult applicability constraint.

Formula and scope findings

• The formula is the standard Deurenberg adult estimate only when sex is encoded as 1 for male and 0 for female: BF% = 1.20·BMI + 0.23·age − 10.8·sex − 5.4.
• The specification does not define the required sex encoding, creating an exact input ambiguity.
• The formula is intended for adults; the specification does not state or enforce an adult-age constraint. It should not be presented as validated for children or adolescents without a separate formula.

Unit assumptions

• BMI is expressed in kg/m².
• Age is expressed in completed years.
• Sex is numeric: male = 1 and female = 0.
• The output is a percentage-point value, such as 27.9%, not a fraction from 0 to 1.

Boundary hardening

BREAK_CLAIMED · SELF_FLAGGED

The plain arithmetic engine can return Infinity for extreme finite JavaScript inputs, and it produces a negative body-fat estimate at the zero boundary instead of rejecting nonphysical inputs.

Errata and corrections

No applied erratum is attached to this unique-name record.

Inspectable example

4 review vectors are recorded. One source-bound sample is shown below.

{
  "inputs": {
    "BMI": 22,
    "age": 30,
    "sex": 0,
    "sex_encoding": "female=0, male=1"
  },
  "expected_outputs": {
    "body_fat_percent": 27.9
  },
  "working": "BF% = 1.20×22 + 0.23×30 − 10.8×0 − 5.4\n= 26.4 + 6.9 − 0 − 5.4\n= 33.3 − 5.4\n= 27.9%"
}

Related workflows

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json · VERIFIED_CLEAN
• evidence-tranche2/tranche2-results.json
• BOUNDARY_HAZARD_CATALOG.json