Methods & sources

Calories, TDEE and BMR

BMR uses the Mifflin–St Jeor resting-energy equation. TDEE multiplies that estimate by a simplified activity factor (1.4, 1.6 or 1.8). The FAO/WHO/UNU energy report gives broad activity ranges, but it does not validate our exact three-choice mapping or personal energy expenditure. Calories uses a ±10% goal adjustment. It withholds a general calorie target when estimated maintenance is below 1,500 kcal and a fat-loss target when its calorie floor would erase the estimated deficit. These thresholds and goal rules are product choices, not clinical prescriptions. The exact defaults have not been validated as individual recommendations.

The source study sampled ages 19–78; use at age 18 is extrapolated. Accepted inputs are 25–300 kg and 100–250 cm. These are product input limits, not clinical eligibility criteria or proof that the equation is accurate for every body size. We do not offer a fat-loss target for ages 18–19 or BMI below 18.5.

Protein and macros

Protein uses 1.6 g/kg/day, a starting point within the ISSN position stand range of 1.4–2.0 g/kg/day for most exercising adults. Macros uses the same protein target, 30% of calories from fat, and the remainder from carbohydrate. The 30% default falls within the adult NASEM fat range, but the exact split is a product choice. The energy arithmetic uses the 4/4/9 kcal-per-gram convention.

BMI

BMI is kilograms divided by metres squared. We use CDC adult screening categories for ages 20 and over. It is a screening measure, not a body-fat measurement or diagnosis.