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The reference library

Every number in Kriterion can be traced to something: a lab measurement, a published study, or your own logged data. These are the explanations the app itself carries, written to be read rather than cited. A selection is here; the rest are in the app.

An Estimate With No Error Bar Is a Guess in a SuitAdaptive maintenance calories come with an interval showing how far the estimate could be off. A narrow one means your scale data is consistent, not that the number is right.Metabolism · 3 min read Why 7,700 Calories Per Kilogram Is Only Roughly TrueA kilogram of fat is worth about 7,700 kcal. That is a fair figure for pure fat tissue, and only a rough one for real weight loss.Weight · 2 min read How Fast Should You Actually Lose Weight?Faster is not better past a point. Around 0.5-0.7% of bodyweight a week best preserves lean tissue, with about 1% a common ceiling.Weight · 2 min read What a Calorie Count Actually CountsCalorie counts rest on average energy values for protein, carbohydrate, fat and alcohol. Fibre and food-specific values are where the averages go wrong.Nutrition · 2 min read Protein Timing, Not Just ProteinTwo days with the same protein total can do very different things for muscle. How it is spread across your meals matters, not just the daily number.Nutrition · 2 min read Why Your Micronutrient Targets Aren't Everyone'sReference intakes are set separately for men and women and change with age, because requirements genuinely differ. Kriterion uses yours.Nutrition · 2 min read Why Your Sleep Target Isn't Eight HoursSleep need varies by more than an hour between healthy adults. Kriterion learns your target from your own best nights, held within 7 to 9 hours.Sleep · 2 min read Reading Heart Rate Variability ProperlyHRV is informative and often misread. It only means something against your own baseline, measured at a consistent time and averaged over a week.Recovery · 2 min read The Problem With 220 Minus Your Age220 minus age was never derived from a proper study. Tanaka's 208 minus 0.7 times age fits the data better, especially later in life.Cardio · 2 min read Why Your Workout Might Not Add Calories BackRaw exercise calories include the energy you would have burned at rest anyway, and your target already counts that. Adding them back counts it twice.Metabolism · 2 min read Your Watch Is Wrong. That Is Not the Same as Useless.Wrist devices are poor at estimating the calories you burn. They tend to be wrong in a consistent way, and that consistency is what Kriterion uses.Metabolism · 3 min read Estimating the Cost of Lifting WeightsOne MET value for weight training ignores what you actually lifted. Kriterion estimates a session's cost from the physics of the lifts instead.Training · 2 min read Hard Is Only Hard in ContextThe acute:chronic workload ratio compares your last 7 days with your last 28, so a hard week is judged against what you are conditioned for.Training · 2 min read Estimating a One-Rep Max Without Testing OneYou can predict a one-rep max from a set taken close to failure, as long as the set was not too long.Training · 1 min read Where Your Body Fat Estimate Comes FromEvery body fat method in Kriterion is a published equation, and each trades accuracy against how much you have to measure.Body Composition · 2 min read How Your Adaptive Target LearnsPremium's Adaptive Target starts from a formula, then corrects it a week at a time from what you ate and what your weight actually did, until your own data carries the answer.Metabolism · 4 min read Does Your Cycle Phase Change How You Should Train?The phase articles describe what is common, not what will happen to you. The difference between two women dwarfs the difference between two phases.Cycles · 2 min read FFMI Norms: Why 25 Is Not a Natural LimitFat-Free Mass Index scales lean mass to height. The famous 25 'natural limit' does not survive the paper it came from.Body Composition · 3 min read DOTS vs WilksDOTS and Wilks both score a powerlifting total against bodyweight. DOTS is the newer formula, fitted to modern drug-tested raw lifters.Training · 2 min read GLP-1 Medication: Keep the MuscleGLP-1 medicines make eating less far easier. Protecting the muscle underneath still takes work: enough protein, and lifting.Weight · 2 min read Training ReadinessReadiness is a weighted average of the recovery signals you actually have. Anything your setup cannot measure is left out, not filled in.Recovery · 3 min read Creatine: The Supplement That Earns Its PlaceCreatine adds a little extra strength and muscle on top of training, costs little, and has a strong safety record. It works by building up, so daily beats timing.Nutrition · 2 min read Why the Scale Jumps After a Salty or High-Carb WeekendA heavy weigh-in after a salty or carb-heavy couple of days is mostly water, not fat. It passes, and the weekly trend is what tells you about fat.Weight · 2 min read How Many Sets per Muscle per Week?Muscle growth rises with the hard sets you give a muscle each week, with diminishing returns. Around ten or more a week is a sound target for most people.Training · 2 min read Deload WeeksA deload is a planned lighter week that lets built-up fatigue clear. Its job is recovery and consistency, not extra growth.Recovery · 2 min read

Kriterion is the app this reasoning is built into

It measures your maintenance calories from what you actually ate against what the scale actually did, tells you how firmly the number is pinned down, and checks its own past predictions against your results. Free logging, UK food data, and no ads.