Kriterion vs Nutracheck

This is the comparison a British person actually makes, and it is the one where the honest answer is least convenient for us. Nutracheck is a UK company with a UK food database built over years, and on the thing most calorie apps get wrong here — knowing what a Tesco own-brand lasagne or a Greggs steak bake actually contains — they are not the weak option. They are the reason the American apps feel wrong to use in Britain. The difference is not the food data. It is what happens after you log it.

Credit where it’s due Nutracheck solved the UK food problem before anyone else took it seriously. Open MyFitnessPal in Britain and you get a wall of user-submitted entries for American products, three versions of the same supermarket item with different numbers, and no way to tell which one somebody typed in wrong. Nutracheck went and did the boring work instead: verified UK products, supermarket own-brands, and the high-street chains people actually eat from.

They also do something almost nobody else bothers with, which is photographs of the products, so you can tell that the thing you are about to log is the thing in your hand. And they track what a British label tracks — salt and fibre alongside the macros — rather than translating from an American convention. That is a decade of unglamorous curation and it is worth more than any single feature on a comparison table.

So here is the actual difference, in one sentence. Nutracheck tells you what you ate. It works out what you should eat by taking your height, weight, age and sex, estimating your resting metabolism from them, and multiplying that by an activity level you choose from a list at signup. That is the same arithmetic every calorie app has used since the 1990s, and it is a reasonable place to start. What it cannot do is find out whether the multiplier you picked was right. Kriterion measures the answer instead: it compares what you actually logged against what the scale actually did, and derives your maintenance calories from your own results rather than from a category you selected about yourself.

	Kriterion	Nutracheck
UK food data	UK government lab data (CoFID), plus UK chain menus and supermarket products, each entry marked with where it came from	A large, verified UK database with supermarket own-brands and chain menus. Their strongest suit, and genuinely theirs
Product photographs	Not offered	Yes, on a large share of the database. Useful, and we do not have it
How your calorie target is set	Measured from your logged intake against your weight trend. No activity level to pick, because it is derived rather than declared	Estimated formula: resting metabolism from your stats, times an activity multiplier you choose at signup
Target adapts to your results	Continuously, weighted towards your last seven days of weigh-ins	Recalculates when your weight or your stated activity level changes; the multiplier itself is still the one you picked
Shows its error margin	Yes, as a spread — “1,870 ± 49 kcal” — so you can see how firmly the number is pinned down	Not published. The target is presented as a figure
Checks its own past predictions	Yes. Replays what it believed a fortnight ago against what the scale did, and tells you the gap	Not offered
Barcode scanning	Yes	Yes
Salt and fibre tracked	Yes, alongside the macros and micronutrients	Yes — they were doing this when the American apps were not
Strength training	Built in: sets, reps, RIR, readiness, a HIIT timer with spoken cues	Exercise is logged as calories burned rather than as training
Menstrual cycle tracking	Built in, feeding readiness and training guidance	Not offered
Free tier	Logging is free and unlimited, permanently, with no card required	A free tier exists with limits on the diary; the full app is a subscription
Platforms	iOS, Android, Apple Watch, Wear OS	iOS, Android, Apple Watch

The honest read: if what you want is the fastest way to log British food accurately, Nutracheck does that well and has done for years, and you will not be badly served. Choose Kriterion if the number you are eating to matters as much as the logging — if you want it measured from your own results rather than assumed from a dropdown, and you want to be told how much confidence it deserves.

Where Nutracheck has the edge: the database is deeper on UK packaged groceries than ours, the product photographs are a real usability advantage we cannot currently match, and they have a decade of UK users and UK support behind them. They are a British company that has been answering British emails about British food for years. Kriterion is new. That history is not nothing, and no feature list makes it go away.

They also have features we have deliberately not built, including a 5:2 fasting mode and a long-running user community. If either of those is why you would use an app, we are not the better choice and we would rather say so here than have you find out in week two.

Why the activity multiplier is the whole argument

Every formula-based calorie app asks you the same question near the start: how active are you? Sedentary, lightly active, moderately active, very active. Your answer picks a number, usually somewhere between 1.2 and 1.9, and your resting metabolism is multiplied by it. That product is your maintenance calories, and every target the app ever gives you is built on it.

The trouble is that the gap between the bottom and the top of that scale is enormous. On the same person, the difference between “lightly active” and “very active” can be six or seven hundred calories a day. Nobody knows which one they are. Desk workers who go to the gym four times a week pick different answers for identical lives, and people who are dieting tend to pick optimistically. You are being asked to supply the single most important input, about yourself, before you have any evidence.

Then, crucially, nothing checks it. If you picked wrong, the target is wrong by that much for as long as you use the app, and the only signal you get is that the weight is not moving the way it said — which most people read as a personal failure rather than as a wrong multiplier.

Kriterion never asks the question. It watches what you logged and what the scale did, and solves for maintenance from those two things. If you eat 2,100 a day for three weeks and lose half a kilo, your maintenance is not a category you selected; it is arithmetic. That is the whole of the difference, and it is also why the food database has to be good: the measurement is only as honest as the logging underneath it, which is the one thing Nutracheck has always understood.

What we will not claim

We do not have the only UK food database, and it would be a lie to imply it. That claim gets made a lot in this category and Nutracheck is the standing refutation of it. What we have is UK government lab data, UK chain menus, and a source label on every entry so you know whether a number came from a laboratory, a manufacturer or a stranger. What we have that they do not is the engine that turns your logging into a measured figure with a stated margin of error.

We are also not claiming to be more accurate at logging. Their database is older and deeper on packaged groceries, and their photographs make it harder to log the wrong thing. If we said otherwise you would find out within a week.

And the measured approach has a real cost. It needs a few weeks of consistent logging and regular weigh-ins before it says anything confident, and it tells you so rather than pretending otherwise. A formula gives you a number on day one. If you want a target this afternoon and you will not weigh yourself often, the formula is genuinely the better tool for you, and Nutracheck is a good implementation of it.

What the ± is for

One number hides how much of a guess it is. “1,870” looks identical whether the app has three months of your data or three days. Kriterion shows the spread as well, so a tight range tells you the weigh-ins agree with each other and a wide one tells you there is too much scatter to act on yet. Under the hood it is a 95% confidence interval on your weight trend, built with a Student’s-t value rather than the usual shortcut, which matters precisely in the first few weeks when a handful of weigh-ins would otherwise look far more certain than they are.

What it does not claim: a tight spread means your scale data is consistent, not that the number is true. The larger error in any app like this is under-reported food, which the tracking literature puts at 20% or worse. That is a bias rather than random scatter, so no honest interval can include it. We would rather say that than hand you a range that quietly implies more than it knows. (1,870 ± 49 is an illustration; yours will differ.)

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