Disclaimer

How the figures are calculated

The app shows three groups of numbers. Below is the formula and the source for each. The same list, with full bibliographic references, is available on the methodology screen in the app (Settings → Legal information).

Estimated daily calorie need

Basal metabolic rate from the Mifflin–St Jeor equation, multiplied by an activity factor (1.2 / 1.3 / 1.4) and a goal factor (0.8 / 1.0 / 1.2). Those two multipliers are practical planning factors; they are not part of the cited equation, and the app says so plainly.

Source: Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO. "A new predictive equation for resting energy expenditure in healthy individuals". Am J Clin Nutr. 1990;51(2):241-247.

Protein, fat and carbohydrates

Protein — 18% of energy, but not below 0.83 g per kilogram of body weight (1.0 g/kg from age 65); fat — 27% of energy; carbohydrates — the remainder.

Sources: IOM/National Academies, Dietary Reference Intakes, 2005 (the AMDR ranges and 130 g of carbohydrate per day); EFSA, Dietary Reference Values — protein 2012, fat 2010, carbohydrates 2010; WHO, 2023 guidance (total fat ≤30% of energy); DGE/ÖGE/SGE 2019 (1.0 g of protein per kg from age 65).

Body-weight range

A published BMI band multiplied by height in metres squared. This is a population reference point, not an ideal or target weight: BMI does not distinguish muscle from fat and takes no account of build.

BMI itself carries no age correction — age only decides which band applies (and below 19, so does sex):

• ages 14 to 18 — the WHO "BMI-for-age" reference (the 5–19 growth reference), with separate curves for girls and boys. The band runs from the thinness threshold (−2 SD) to the overweight threshold (+1 SD) for that year of life. This is why sex is required at these ages: the curves diverge by as much as a whole BMI point, and averaging them would mean showing a number that appears in no source
• ages 19 to 64 — 18.5–24.9
• age 65 and over — 22–27. BMI cannot see loss of muscle mass, and in older age groups the lowest mortality sits above the adult band, while a BMI below roughly 23 is associated with raised risk

The adolescent band covers a whole year of life. The WHO tables give a row for each completed month, but we ask for age in years and do not know the month of birth, so the lower bound is taken from the start of the year (−2 SD at "14:00") and the upper bound from its end (+1 SD at "14:11"). The resulting band is wider than any single row of the table — deliberately: picking one row would move the upper bound by up to 0.8 BMI on a guess about someone's birthday, and specifically in the direction of "you are above the range" for a teenager who is not. The numbers are taken from the printed WHO columns without recomputation, so every one of them can be checked straight against the table.

At 19 the band jumps — from 17.3–25.4 (boys) or 16.4–25.0 (girls) to 18.5–24.9. This is neither an error nor something we smooth over: it is the switch between two different references, and WHO built the adolescent one so that its +1 SD meets the adult overweight threshold at 19, not so that both bounds would meet.

The three bands rest on different kinds of evidence, and we do not pretend otherwise. 18.5–24.9 is a classification standard with fixed cut-offs. The adolescent band is a percentile reference — a statement about the distribution in a population, not about one child's health: at that age what matters is the curve over several years rather than a single point, and a clinician is the one who reads it. 22–27 is established geriatric practice generalised from observational mortality data: sources differ by a point or two either way, and the mortality curves themselves would permit a higher upper bound. We take the more conservative edge, because the number is seen by someone who has not asked a doctor.

Sources: WHO consultation on obesity 1997 → NHLBI Clinical Guidelines 1998, table IV-1 (18.5–24.9); de Onis M, Onyango AW, Borghi E, Siyam A, Nishida C, Siekmann J. "Development of a WHO growth reference for school-aged children and adolescents". Bull World Health Organ. 2007;85(9):660-667, together with the published BMI-for-age z-score tables for boys and girls aged 5–19 (the adolescent band); Winter JE, MacInnis RJ, Wattanapenpaiboon N, Nowson CA. "BMI and all-cause mortality in older adults: a meta-analysis". Am J Clin Nutr. 2014;99(4):875-890 (the raised bounds from age 65).

When no number is shown at all

Where a calculation falls outside the published sources, the app shows no number and explains why, rather than bending the result to fit:

• a calorie target below 1200 kcal per day (women) or 1500 kcal (men) is not displayed. This is our own product safety rule, not a requirement of the formula — the equation itself has no lower bound; these two thresholds have no separate source, and the app says so plainly
• macronutrient figures are not displayed if they fall outside these limits: protein 10–35% of energy, fat 20–30%, carbohydrates 45–60% and not below 130 g per day. The app will not push protein or fat below the published bounds to make the arithmetic add up
• a calorie target is shown only for profiles aged 19 and over with sex recorded as male or female — the Mifflin–St Jeor equation defines no calculation for other values
• the body-weight range below age 19 is not shown until sex is given — the WHO adolescent reference is published as two separate curves, for girls and for boys, and no third, combined one exists

Who these calculations are not for

The formulas are not adapted for pregnancy, breastfeeding, kidney or liver disease, metabolic disorders, or any other condition that changes energy or protein requirements. The health questionnaire in the app is kept as reference information and changes none of the numbers shown.

Calories in recipes

The calorie and macronutrient values in recipes, in the meal plan and in the shopping list are approximate catalogue estimates, entered by hand for each recipe. They do not come from an external nutrient database and are unrelated to the personal calculation described above.