What are the three numbers?
Maintenance calories are the daily intake at which your weight stays the same, because what comes in matches what the body uses. Nobody measures that at home; it is estimated. The best-studied equation for the resting part, Mifflin-St Jeor, landed within 10 percent of the measured resting figure for most people, not all, in the 2005 review by Frankenfield and colleagues, and the activity factor that turns it into a day's figure, about 1.4 to 2.4 on the FAO/WHO/UNU scale, is a self-assessment. So maintenance is a range with a number in the middle, not a fact.
A calorie deficit is a period during which you take in fewer calories than your body uses; a surplus, more. It is the gap that swings hardest for someone whose training week is never the same twice, and a gap between an estimate and a record, which nobody can measure directly, because the side the body used is never recorded. The CDC describes a pace rather than a number: the CDC writes that people who lose weight at a gradual, steady pace of about 1 to 2 pounds a week "are more likely to keep the weight off than people who lose weight quicker", read 14 September 2026; that pace is theirs to describe and yours to decide on, with someone qualified if you want one.
The calorie target is the daily number you choose to aim at, above, below or at your maintenance, and the only one of the three a record can hold you to, because it is the only one that is a number rather than an estimate or a gap. It can carry protein, carbohydrate and fat in grams beside the calories, or any one of the four alone.
| The number | What it is | Who sets it | What IZeat does with it |
|---|---|---|---|
| Maintenance | What your body uses in a day | An estimate: an equation and an activity factor, yours or a clinician's | Nothing: IZeat does not calculate or store it |
| Deficit or surplus | The gap you choose between maintenance and intake | Your decision, with the pace the CDC describes if you want a reference | Nothing: IZeat cannot see the other side of the balance |
| Target | The daily figure you aim at, calories and, if you want, macros in grams | You, by conversation, from the day you say | Stores it with its start date, keeps the history, compares each day to the target in force that day |
Bottom line: two of the three are yours to estimate and decide; the third is the one IZeat records and compares the day to.
How is the target set, and changed?
IZeat is the calorie tracker inside ChatGPT, Claude or any other assistant. Tell the assistant you already use what you ate instead of searching for foods and entering them one by one. The target is set the same way, in the conversation, and there is no settings page for it: you say the number, the assistant is asked to record it through IZeat from the day you name, and the reply is signed with the target as stored.
"Set my target to 1 800 kcal and 130 g of protein from Monday." The receipt states the target and its start date. A target is never edited in place: a new one is a new line with its own date, and the history stays, so a day in August is still read against the target that was in force in August, and a day before your first target is shown with its totals and no remainder, never judged against a number set after it. Ask "what is my target?" and the assistant reads it back, signed, with the date it started.
The first time, the assistant is asked to run a short setup: your first and last name, then the daily target you already use, calories and, if you want, protein, carbohydrate and fat in grams. You can say "later" at any step; a missing target never blocks a meal, and a day without one shows its total without a remainder. What IZeat does not do is propose the number: it does not calculate a maintenance, it does not recommend a deficit, and it does not flag a target as too low or too high. If you ask, the assistant may help you estimate one as your general assistant, outside IZeat and kept separate from the receipt; that discussion is the assistant's, never an IZeat calculation, and only the figures you then choose are stored.
What does IZeat hold about you, and what does it not?
What the profile holds is short enough to list: a first and last name, a time zone so your days are counted where you live, and the targets you set, each with the date it started. There is no sex field, no age, no height and no weight anywhere in the record, which is why the product can say it applies no formula to you: it holds nothing to apply one to. The cost of that is real, and it is the same for everyone, so if you want a starting figure the arithmetic is yours to do, or your assistant's, or a clinician's.
What a target is not: a target is a number you chose, compared to a record you kept. It is not a measure of what your body needs, and the remainder on the day is a distance to your own number, not a verdict on the day. Over and under are stated the same way, a number and a unit, and nothing turns red because you ate.
What does a day look like against the target?
A list with a total, and a remainder. After lunch on a day with a 1 800 kcal and 130 g protein target, a signed read says the total so far, then what is left: "Against the target: 845 kcal remaining · 62g protein remaining"; a day that went past it says "120 kcal over target" in the same tone. A nutrient without a target gets no remainder, since it earned none. The day report article goes through the card.
Wednesday, 4 pm, on the phone: "What is left for tonight?" The assistant reads the day from IZeat and relays the signed line: 640 kcal and 58 g of protein remaining against the target you set on Monday. What to do with that is yours: cook to it, go past it, or change the target from tomorrow because a week of days told you the number was wrong. Each of those is one sentence, and the record shows which you did.
Frequently asked questions
Short answers to the questions people type, each one sourced above.
What is the difference between maintenance calories and a calorie target?
Maintenance is what your body uses in a day, an estimate made from an equation and an activity factor, with a range around it. A target is the number you choose to aim at each day, at, below or above that estimate. A record can compare a day to a target, because it is a number you set; it cannot compare a day to maintenance, because nobody measured it. IZeat stores the target and estimates nothing.
How do I know my maintenance calories?
You estimate them. The formula way: resting energy from age, sex, height and weight with a published equation, then an activity factor; the best-studied equation lands within 10 percent of measurement for most people at rest, and the factor is a guess. The observed way: record what you eat for a few weeks while your weight holds, and take the average per recorded day, with the record's own uncertainty in it.
Does IZeat calculate my calorie deficit?
No. A deficit is the gap between what your body used and what you ate, and the first of those is never recorded, so no record can measure it. IZeat shows the day's total against the target you chose and what is left, in the same words whether the day was under or over. How far your target sits below what your body uses is an estimate, yours or a clinician's, and IZeat does not make it.
How do I set a calorie target in IZeat?
In the conversation, from the day you say: "set my target to 1 800 kcal and 130 g of protein from Monday". The assistant is asked to record it through IZeat, and the reply is signed with the target and its start date. Calories alone, macros alone or both work. A new target is a new dated line; the earlier ones stay, and each day is read against the target in force that day.
Will IZeat tell me if my target is too low?
No. An adult may set whatever target they want; IZeat records it and compares the day to it, and it does not flag, block or lecture. Nothing in IZeat asks the assistant to comment on your target; whatever it says about it is its own, in its own voice. The CDC describes a gradual pace of about 1 to 2 pounds a week as the one after which people are more likely to keep the weight off; that is theirs to describe. If you are unwell or unsure, the conversation to have is with someone qualified.
Can I change my target for one day only?
A target starts on a day and stays until the next one starts, so a one-day change is two lines: the new target from that day and the old figures entered again from the day after. Both are recorded with their dates and the history keeps them. The simpler change is usually a target set from tomorrow, after a week of days showed the number was off, rather than a day carved out.
What happens on days before I set a target?
They show their totals and no remainder. A day is never judged against a target set after it: the target has a start date, and days before it are read as what they were, a list with a total. The same holds for a day when you said "later" during setup and recorded meals anyway; nothing was blocked, and nothing is compared to a number that did not exist yet.