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iPhone. iOS 15.1 or later.

Nutrition

Calorie calculator: a target that moves with your weight

The calculator gives you a starting guess. The scale gives you the answer. Here is the rule that connects them, and the floor under it.

Calculate your starting calorie target

About you

The equation needs four things. The app asks for the same four.

Your week

Pick the honest one. Most people who train are moderately active, not very.

Moderately active: 3–5 sessions a week. Multiplier 1.55.

Where the app would start you

—kcal a day

Resting (BMR)
—
Maintenance
—
Floor
—
Protein
—

Sex, age, height and weight, then a number. Mifflin–St Jeor for the resting rate, the activity multiplier for the day, the goal on top, and the floor under all of it.

Nothing typed here leaves the page. The app starts here, then moves the target by 100 kcal a day from your weight trend.

This calculator and guide are general information for healthy adults, 18 and over, and not medical advice. The calorie and protein figures are not for anyone who is under 18, pregnant or breastfeeding, has a medical condition or a history of disordered eating, or takes regular medication. If that is you, a doctor or a registered dietitian should set the number. Questions about the app are in the FAQ.

Published
Updated
By
Lakshay Bhati, Liftor. Checked against the app's source.

How many calories should you eat to cut or to gain?

Start from an estimate of what you burn at rest, add activity, and then shade it: roughly 300–500 kcal under maintenance to lose fat at a sustainable rate, 200–300 over it to gain muscle without gaining much else. The resting estimate most apps use is the Mifflin–St Jeor equation, published in the American Journal of Clinical Nutrition in 1990, from sex, age, height and weight. It is accurate to within about ten percent for most people, which means the first target is a guess in the right neighbourhood and nothing more.

For an 80 kg, 178 cm man of thirty the equation puts rest at about 1,770 kcal a day; with a desk job and four sessions a week his maintenance lands near 2,740, so a cut starts around 2,330 and a gain around 3,010. The number that matters is not the estimate. It is what the scale does over the following weeks.

How does Liftor adjust the calorie target?

By one hundred, or not at all. Each day the app looks at the seven-day trend of your bodyweight against the direction your goal wants, and moves the day’s target by −100, 0 or +100 kcal. A cut that has stalled for a week gets a hundred fewer; a gain that is outrunning the plan gets a hundred fewer too; a trend that is doing what it should is left alone. If your steps are connected, a second term adjusts for an unusually active or idle day. One step, weekly evidence, no hundred-calorie guesses stacked on top of each other.

The note under the number says why: “trend flat for seven days” rather than “calories adjusted”, so you can disagree with it on the facts.

Is there a lowest calorie target?

Yes: your resting rate plus 100 kcal. Eating below the basal metabolic rate for a stretch of time is where the body starts economising — on muscle, and on the rate itself — so Liftor will not write a daily target under Mifflin–St Jeor’s estimate for you plus a hundred, whatever the trend says. When the floor is what set the number, the note says so, and the app stops nudging until the picture changes. If the profile is missing a height or an age the estimate falls back high, on purpose.

How fast should the scale move?

Half a percent to one percent of bodyweight a week on a cut, and slower than that on a gain. The evidence review Helms, Aragon and Fitschen published in 2014 for natural bodybuilders — the population that has most to lose from losing muscle — set caloric intake at a level that produces bodyweight losses of about 0.5 to 1% a week to maximise muscle retention. For an 80 kg lifter that is 400–800 g a week, which is why the app’s 15% deficit is a starting point rather than a floor, and why it moves in 100 kcal steps rather than 500.

Gaining is slower because muscle is built slowly and the rest of a large surplus becomes something else. Liftor’s gain adjustment is +10%, milder than its cut, and the weekly trend pulls it back by 100 kcal when the scale is outrunning the plan. A gain that shows up as a kilogram a week is mostly not muscle, however good it looks on the graph.

How much protein should you eat?

About 1.6 grams per kilogram of bodyweight a day, and a little more will not hurt. Morton and colleagues pooled forty-nine trials and 1,863 people in 2018 and found that protein supplementation improved gains in strength and lean mass during resistance training, and that the gains in lean mass plateaued at a total intake of about 1.6 g/kg/day; the confidence interval on that break point ran up to roughly 2.2. Liftor writes 1.8 g/kg as the default and 2.2 g/kg when the goal is to gain — above the plateau on purpose, because protein is cheap insurance and the cost of undershooting it is muscle.

On a hard cut the number goes higher still: the 2014 review recommends 2.3–3.1 g per kilogram of lean mass for competitors in a deficit. For most people the arithmetic lands in the same neighbourhood as the app’s 1.8–2.2 of total bodyweight, and the meal plan hits it with food before it reaches for a shake. If a supplement does come into it, the upper limits are worth knowing first.

Why does the scale move a kilogram overnight?

Water, mostly. Each gram of glycogen the muscles store is stored with roughly three grams of water, so a high-carbohydrate day after a low one can add a kilogram that has nothing to do with fat; salt holds water, a late meal is still in you at weigh-in, and a hard session can swing it either way. None of it is progress and none of it is failure. It is noise on a signal that only shows up over weeks.

That is the whole reason the app reads a seven-day trend and never a single weigh-in. Weigh yourself at the same time each morning if you like the ritual, and then let the trend decide: a target that moved because Tuesday was salty is not a target. The note under the number in Liftor says “trend flat for seven days” rather than “you gained weight”, because the second sentence is usually not true.

Sources