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 tightly your own weigh-ins pin the number down, and nothing more than that. The trend behind your figure sits inside that band nineteen times out of twenty, which is what “95% confidence” means in plain English. It is the strictest of the standard intervals, so ours reads wider than it strictly needs to. We would rather that than the reverse.

In practice it usually shows in the low hundreds of kcal. It narrows over your first couple of months and then settles, and it is worth knowing why: what limits it is how much a bathroom scale jumps about from one week to the next, not how hard the app is working. Settling is not the app giving up. It also widens on its own if you stop logging for a while, rather than holding still and implying it still knows what it knew a fortnight ago.

One thing it cannot see is whether you are under-reporting your food, because nothing in your logged data measures that. A tight band tells you your weigh-ins agree with each other, which is worth knowing and is not the same claim. For whether the number is actually right, see the next question.

How do I know the calorie number is actually right?

No app can prove it outright, and one that says otherwise is overreaching. Proving it would mean knowing your true expenditure, and that takes a metabolic chamber rather than a phone. So Kriterion does the next honest thing: it marks its own homework.

It replays what it believed your maintenance was at points across your own history, using only the data it had at each of them, works out what your weight should have done given what you actually ate, and compares that against what your scale really did. The result sits under your maintenance figure in plain words: that your results have been running ahead of the plan, behind it, or tracking it closely.

It also tells you how tightly that check itself is pinned down. Unlike the ± on the target, that figure keeps sharpening as the weeks accumulate: it starts loose and comes down into the tens of kcal a day by around the fourth month, sooner if you weigh in most days. The check needs about six weeks of results behind it before it can say anything, and it stays quiet until then rather than guessing. From your first week the same card shows you something else that moves: how much of your target is already coming from your own data rather than the formula it started as.

What it deliberately will not do is tell you why a gap appeared. Expenditure, logging drift and weigh-in conditions all produce the same arithmetic, and the honest answer is that this cannot tell them apart.

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. Connect a watch or ring and readiness reads your HRV and resting heart rate every morning. With a phone alone, readiness leans on the sleep your phone records and on how you say you feel. Sleep can also be logged by hand for your sleep history, 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 stays on the device, there is no per-scan cost, and there is no daily limit on it for anyone.

Two things do leave. When you check a barcoded food against its label, the figures it read are sent with the barcode, so matching reads from many people can confirm that product's numbers. That is on by default, carries nothing about you beyond a hashed install ID, and you can switch it off in Settings under Security & Privacy, Help improve food data. And a photo is only ever sent if you choose to attach it to a correction.

Why is there a daily barcode scan limit?

Barcode lookups query our own food database, unlike label photos which are read on your device. Every lookup hits an index we build and host ourselves rather than a free public one, which is why that particular action carries a cap and nothing else does. 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, no correction is submitted and you're told why, rather than a mismatched packet quietly corrupting an entry. The figures it read are still shared to help confirm that product's numbers, unless you have switched that off in Settings.

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, and an export of everything you have logged whenever you want it. Unlimited label and scale photo reading, ten barcode scans a day, and the whole food database, every source, nothing held back.

What does Premium add?

Your measured burn rate and the spread on it, adaptive Blueprint, a weekly check-in, the full analytics set, measurement trends and progress photo comparisons, readiness explained and cycle insights.

The caps come off saved routines, saved recipes and barcode scans, and you hold up to five streak shields at once instead of two. It also adds micronutrient trends by week and month, supplement insights, coach tone, the 1RM predictor and DOTS, plans written for you, specialist training methods, run coaching, adjusting today’s session and recipe import.

Why does the free plan only save two routines I build myself?

Because a library of your own routines is one of the things Premium is for.

It only counts routines you wrote yourself. Every standard programme (push/pull/legs, upper/lower, full body and 5x5) is free and uncapped however many days it has, so a free push-pull-legs user has four sessions in their list before touching the limit at all. You can run a one-off session without saving it, or import one somebody sends you and train it today. The limit is on keeping a library, not on training.

What happens to my routines if I stop paying?

Nothing is deleted, ever. If you drop back to the free plan holding more routines than it allows, the extras are locked rather than removed: they stay in your list, greyed out, with everything you wrote still inside them, and they unlock the moment you resubscribe. You keep your three routines; the free plan builds two. If you hold more than three, you pick which three stay active, and if you do not pick, the app keeps the most recent.

Your training history is yours, whether you are paying or not. The one restriction is that changing which routine is active is limited to once a week on the free plan.

When does the free trial start?

You get the whole free app from the minute you install it: unlimited logging, the full food database, your entire history, the standard programmes and the workout logger. Nothing is held back while you wait.

Every free account can start a 14-day free trial of Premium from day one, through the App Store or Google Play. The store asks for a payment method to start it, and the subscription renews unless you cancel at least 24 hours before the trial ends. The measured burn rate sharpens as your own weigh-ins and log arrive, so the first days lean on the formula and the figure then moves towards yours.

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 backup and export are for.

On Android you can also turn on a daily backup, free during the beta. It saves the same password-protected file to a place you choose, such as Google Drive, so the copy sits in your own storage rather than on our servers. There is no browser dashboard.

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 Apple Watch and Wear OS. There is no web version.

Does it work properly with UK food?

That is what it was built for first. Supermarket own-brands, packaged groceries and real menu items from high-street chains, taken from the figures those chains publish themselves rather than from somebody’s guess at what was in it. It reads a British label the way a British label is written, salt and fibre included, instead of translating from an American convention.

The wider database is international, and the restaurant coverage starts here and grows outwards.

What does it cost?

Logging is free, permanently, and that is the part you do every day. Premium is a subscription for the measured-burn layer on top of it, monthly or annual. Price to be confirmed.

Everyone on the waiting list gets the founding offer: a lower price, locked in for as long as you stay subscribed. It is capped at the first 1,000 subscribers or 90 days from launch, whichever comes first, and it will not be extended.

Do I need a smartwatch for it to work?

No. The measured burn rate comes from your food log and your weight trend, not from a wrist. If you do wear something, Kriterion will read steps, sleep and heart-rate variability from Apple Health or Health Connect and use them where they genuinely help, and it tells you which signals it actually used rather than quietly filling the gaps.

How is it different from MyFitnessPal?

Three things. There are no adverts anywhere in it, and there never will be. The food data is sourced and badged by where each figure came from rather than crowd-sourced and unattributable. And your calorie target is worked out from what you actually ate and what the scales actually did, rather than set once at signup and left there.

There is a fuller comparison, feature by feature, side by side, on the comparison page.

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.