Reference database · Live since 2025
The live database of calorie-tracking concepts, metabolism science, and the vocabulary the modern quantified-self era runs on.
NutritionDex is an editorially-independent reference database for the vocabulary of modern calorie tracking — TDEE, CICO, macronutrients, energy balance, metabolic adaptation, and the physiological concepts that underpin every diet app, wearable, and quantified-self workflow. Each entry is written and reviewed against primary sources.
Recently added or reviewed
- Mifflin-St Jeor Equation The predictive equation for resting metabolic rate that most calculators default to, derived from body weight, height, age and sex.
- Katch-McArdle Formula A resting metabolic rate equation calculated from fat-free mass rather than total body weight, more accurate in principle and dependent on a…
- Activity Multiplier The coefficient applied to resting metabolic rate to estimate total daily energy expenditure, and the largest single source of error in any …
- TDEE The total number of calories a person burns in a day — the sum of BMR, thermic effect of food, activity, and non-exercise movement.
- BMR The minimum energy a body expends at complete rest to maintain vital functions — measured under strict fasting and thermoneutral conditions.
- RMR Energy expended at rest under non-strict conditions — typically 5-10% higher than true BMR and the value most consumer tools actually estima…
What NutritionDex is
A reference database. Not a blog. Not a coaching service. Not a product review site.
Every entry answers three questions in this order: what does the research community mean by this, how does the consumer tracking stack (apps, wearables, scales, databases) actually use it, and where do those two definitions drift. Primary-source cited. Editor-reviewed before publication. Updated quarterly.
Written for product people, serious trackers, fitness-adjacent engineers, coaches, and new users who'd rather know the vocabulary than guess at it.