Ainonymity Calorie Counter · The method

How a daily calorie target is calculated.

Published 26 September 2026

Every calorie counter hands you a number — for weight loss, for gaining, or for holding steady — and few of them say where it came from. This is the whole method ours uses, the research behind each step, and the part that is a genuine estimate rather than a measurement.

The four figures, in order

The app shows its working rather than just handing you a figure. Each line below is a step, and the app prints all of them on screen beside the result.

• BMI weighs you against your height. It is a ratio, not a verdict — the app prints the figure and does not put you in a category.
• RMR, your resting metabolic rate, is what your body burns doing nothing at all. It is the largest part of the total, and every target starts here.
• Maintenance, or TDEE — total daily energy expenditure — is what a typical day costs you once your work and your exercise are counted in.
• Goal adjustment is the amount added or taken off for the goal you picked, and the suggested target is what comes out at the end.

BMR and RMR are not quite the same thing

You will see both. Basal metabolic rate is measured after an overnight fast, at complete rest, in a controlled setting. Resting metabolic rate is measured under ordinary resting conditions and comes out a few percent higher. Most apps — and most equations, including the one here — use the resting figure and call it either name.

The equation, named

The app uses Mifflin-St Jeor, published in 1990 from measurements of 498 healthy adults. It is the equation a 2005 systematic review found most accurate of the common predictive equations, with the narrowest error band, which is why it is the one here.

Maintenance is then that resting figure multiplied by an activity factor, which is the method the joint FAO / WHO / UNU report sets out. The activity values come from EFSA, which publishes them for work and for exercise separately — so the app asks two questions about your week rather than making you pick one lifestyle word.

What the app will not tell you

Some inputs have no safe answer, and in those cases the app offers no number at all rather than a smaller one. It suggests nothing below 18, because the equation was derived on adults. It will not put an adult below 1,200 kcal a day, or 1,500 for men. It declines a weight-loss target for someone already underweight, and a weight-gain target above a BMI of 25.

One case is different, because the goal itself is fine and only the size of the deficit is not. When the usual 500 kcal deficit would take a target below the floor, the app offers the floor itself, with a smaller deficit, and says so on screen. It stops where that deficit would be less than 300 kcal a day — the smallest deficit the 1998 NHLBI evidence report names — and there it offers no weight-loss target. Both US figures, the 500 and the 300, were written for adults with overweight or obesity; at a normal BMI, the NHLBI advises staying in that range rather than losing weight. The app still offers a weight-loss target there if you choose one, and its reference card says so. Where there is no safe answer the app says so — a refusal is a real answer, and rounding to something plausible would not be.

Those two figures are our own, and we would rather tell you than let them look official. They are the bottom of the range the 2013 AHA/ACC/TOS obesity guideline told clinicians to prescribe — a guideline retired in 2026, by a replacement that sets no daily calorie figure at all. No current authority publishes a minimum that differs by sex. We kept the numbers because stopping higher than anyone asks us to is the safe direction to be wrong in, and because a limit we can explain is better than a limit we borrowed.

It also cannot see body composition. Two people of the same height and weight get the same figure whether the weight is muscle or not, because nothing the app asks could tell them apart. That is a known limit of any height-and-weight equation, and it is why the result is a starting point.

Where all of this comes from

Every source below is in the app too, on the same screen as the figure it supports.

• Mifflin MD et al., 1990 — the resting-energy equation, derived from 498 healthy adults.
• Frankenfield D et al., 2005 — the systematic review comparing predictive equations against measured resting metabolic rate.
• FAO / WHO / UNU, 2001 — human energy requirements, and the maintenance method itself.
• EFSA, 2013 — the dietary reference values the activity factors come from.
• WHO Technical Report Series 894 — the BMI thresholds.
• AHA / ACC / TOS, 2013 — the 500 kcal daily deficit, and the prescribing range our two floors are the bottom of. Retired in 2026; the deficit is separately supported by the 1998 NHLBI evidence report, and the floors are our own choice rather than anyone’s published minimum.

Want to see it working? The app prints every line above on screen, with the source beside it — have a look at Ainonymity Calorie Counter, or see where the food data comes from and why calorie apps give different numbers.