What your body uses in a day, and what intake a given rate of loss would need — with the equations shown, because every calculator that hides them is hiding the same two.
Sex at birth
Age
Weight
Height
Body fat % — optional
Enter one and the calculation switches to Katch–McArdle, which works from lean mass and ignores sex. A scale’s body-fat reading is an estimate; a DXA figure is a measurement.
Activity
Total daily energy expenditure
—kcal/day
Resting (BMR)
—
Protein target
—
1.2–1.6 g per kg body weight
These are estimates, and the honest error bar is wide. Measured resting energy expenditure varies by roughly ±10% around what these equations predict for an individual, and the activity factors are round numbers agreed by convention rather than anything measured about you. Treat the output as a starting point to test against the scales over a few weeks, not as a number to obey.
Protein is the one that matters on a GLP-1. Appetite falls faster than requirement, and lean mass is what gets lost when intake drops and protein does not keep up. The figure above is the usual 1.2–1.6 g per kg range; resistance training alongside it is what the trials consistently show protects lean tissue.
Rows shaded amber fall below the intakes usually considered a floor without supervision (about 1500 kcal for men, 1200 for women). If a rate of loss needs one of those, that is a conversation to have with your prescriber or a dietitian, not a target to set yourself.
Mifflin–St Jeor (1990) — the default, because it only needs what everyone knows about themselves:
men: BMR = 10 × kg + 6.25 × cm − 5 × age + 5
women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161
Katch–McArdle — used instead as soon as a body-fat percentage is entered, because once lean mass is known it is the better estimate, and it does not need to know sex at all:
BMR = 370 + 21.6 × lean kg
TDEE is BMR multiplied by the activity factor shown beside each option (1.200 to 1.900, the conventional Harris–Benedict set).
The loss table uses 7700 kcal per kg of body fat, so 0.5 kg a week is a
deficit of 0.5 × 7700 ÷ 7 = 550 kcal a day. That constant assumes the
weight lost is fat; early weeks lose water as well, which is why the scales usually move faster
than the arithmetic at the start and slower later.
incretly is an information and record-keeping project. Nothing here is medical advice or a recommendation to start, stop or change any treatment or diet. If you are on a medicine that affects appetite, decisions about intake belong with you and your own prescriber.