Questions people actually ask

Why did my calorie target change on its own?

Because it is measured rather than assumed. Kriterion compares what you logged against what you weighed and adjusts your maintenance figure to match what your body is actually doing. A target that never moves is a target that stopped paying attention. The app tells you when it changes and by how much, and it will say it is still calibrating rather than pretend to a precision it does not have.

What does the ± next to my calorie target mean?

It is how cleanly your weigh-ins point at a trend. If it says 1,870 ± 49, eat about 1,870 to hold your weight, and the trend behind that figure sits in a band 49 either side of it — nineteen times out of twenty, which is what “95% confidence” means in plain English. A narrow band means your scale data is consistent. A wide one means there is too much scatter to act on yet.

What it does not mean is that the number is correct. The band cannot see whether you are under-reporting your food, which is the largest real-world error in any app of this kind, and no honest interval can include it because nothing in your logged data measures it. A tight band tells you your weigh-ins agree with each other. That is worth knowing, and it is not the same claim.

How long before the numbers mean anything?

Roughly two to four weeks of reasonably consistent logging. Before that Kriterion leans on a standard formula and says openly that it is still calibrating, rather than presenting an early guess as a measurement. The more consistently you log food and weight, the more the figure comes from your own data instead of the textbook.

Do I need a smartwatch or fitness tracker?

No. Kriterion reads from Apple Health or Health Connect if you allow it, which fills in steps, heart rate and sleep automatically, but everything works without it. Sleep can be logged by hand, and the app will not score readiness off data it does not have rather than inventing a number.

Where does the nutrition data come from?

The UK government's Composition of Foods Integrated Dataset, published by OHID, plus USDA FoodData Central, Open Food Facts, and published menus from real UK chains. Every entry is marked with its source, so you can see which numbers were measured in a lab and which are somebody's estimate.

Does scanning a nutrition label send my photo anywhere?

No. Reading a nutrition label or a scale display happens entirely on your phone, using Apple's Vision framework on iOS and the offline model in Android's ML Kit. The photograph never leaves the device, there is no per-scan cost, and there is no daily limit on it for anyone.

Why is there a daily barcode scan limit?

Barcode lookups query our own food database, unlike label photos which are read on your device. Five a day on the free tier is there so Premium still buys you something, not because a lookup costs us money per scan. Typing, searching and label photos all stay unlimited.

A food's numbers look wrong. Can I fix it?

Yes, three ways: report the data as wrong, report that a barcode resolves to the wrong product entirely, or photograph the packet's own nutrition panel as evidence. That last one is checked on your device against what our record holds — if the panel doesn't match, nothing is submitted and you're told why, rather than a mismatched packet quietly corrupting an entry.

Corrections are queued for review rather than overwriting the record, so a mistake cannot degrade anyone else's search results.

What do I get without paying?

Logging by hand, unlimited and permanently. Your full food history, never truncated. Unlimited label and scale photo reading, five barcode scans a day, and the whole food database with all four sources.

What does Premium add?

Your measured burn rate and the spread on it, adaptive Blueprint, a weekly check-in, the full analytics set, body measurements and progress photo comparisons, and your complete history on export rather than the last 90 days.

The caps come off saved routines, custom exercises and barcode scans, and you get three streak forgiveness days a month instead of one. It also adds the recipe builder, micronutrient trends by week and month, supplement tracking, coach tone, the 1RM predictor, DOTS, supersets and exercise swaps.

Is there an account, and is my log on your servers?

There is no account and no server copy. Meals, workouts, measurements and progress photos live in a private database on your phone. That also means we cannot restore your history if you lose the device, which is what the encrypted export is for.

Can I get my data out?

Yes, at any time, from Settings. The export is encrypted with a password you choose, and it restores onto another device. We never receive it and we cannot read it, so keep the password somewhere safe because we cannot recover it for you.

How do I stop it reading my health data?

Revoke it in Apple Health or Health Connect rather than asking us. The app keeps working without it, with fewer inputs to its scores.

Does it still work if I use hormonal contraception?

Kriterion asks, because it matters. The pill, an implant, a hormonal IUD or an injection substantially flattens the cycle that phase-based guidance assumes, so the app shows framing that fits rather than one that doesn't apply to you.

Is it a contraceptive or fertility tool?

No. Phases are estimated from the dates you enter, and they exist to explain training, energy and appetite. They are not a contraceptive method and not a fertility test. Please use something built for that job.

Which devices does it run on?

iOS and Android, both native, plus Wear OS. There is no web version.

Is Kriterion medical advice?

No. It is a wellness and training tracker, not a medical device, and it does not diagnose or treat anything. Talk to your GP or a registered dietitian before making significant changes to how you eat or train, particularly if you are pregnant or breastfeeding, managing a health condition, taking medication, or have a history of disordered eating.