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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 are worked out by reconciling what you logged against how your weight actually moved.Metabolism · 2 min read Why 7,700 Calories Per Kilogram Is Only Roughly TrueThe rule that a kilogram of fat is worth about 7,700 calories, or 3,500 per pound, comes from Wishnofsky in 1958 and is the basis of nearly every weight…Weight · 1 min read How Fast Should You Actually Lose Weight?Faster isn't better past a point, and the point is measurable. Garthe and colleagues put athletes on either a slow or a fast deficit to reach the same…Weight · 1 min read What a Calorie Count Actually CountsProtein and carbohydrate are conventionally counted at 4 kcal per gram, fat at 9, alcohol at 7.Nutrition · 2 min read Protein Timing, Not Just ProteinTwo days can carry an identical 150g of protein and be nothing alike. Eaten as one large dinner, most of it arrives in a single sitting past the point…Nutrition · 1 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.Nutrition · 1 min read Why Your Sleep Target Isn't Eight HoursIndividual sleep need varies by well over an hour between healthy adults, so a fixed eight-hour target tells a natural seven-hour sleeper they are…Sleep · 1 min read Reading Heart Rate Variability ProperlyHRV is the variation in time between consecutive heartbeats, and it tracks how much your parasympathetic nervous system, the recovery side, is currently…Recovery · 1 min read The Problem With 220 Minus Your AgeThe best known formula in fitness is also one of the least accurate. "220 minus age" was never derived from a proper study.Training · 1 min read Why Your Workout Might Not Add Calories BackA MET is a multiple of resting metabolism, so 1 MET is simply lying still. That means the raw MET calculation for an activity already contains the…Metabolism · 1 min read Your Watch Is Wrong. That Is Not the Same as Useless.Consumer devices are poor at estimating energy expenditure, and this is not a close call.Metabolism · 3 min read Estimating the Cost of Lifting WeightsCardio is straightforward to price: steady effort, a known MET value (a multiple of what you burn lying still), measured duration.Training · 1 min read Hard Is Only Hard in ContextA training log records how much you did. It cannot tell you whether that was a lot, because the same session is routine for someone training consistently…Training · 2 min read Estimating a One-Rep Max Without Testing OneYou can predict your one-rep max from a set taken close to failure, and there are dozens of published formulas for it.Training · 1 min read Where Your Body Fat Estimate Comes FromEvery body fat method in Kriterion is a published equation, and each trades accuracy for how much you have to measure.Body Composition · 1 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.