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.https://nutritiondex.com/en-ushttps://nutritiondex.com/glossary/tdee/https://nutritiondex.com/glossary/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.Sat, 18 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/cico/https://nutritiondex.com/glossary/cico/The energy-balance framework stating that body-weight change over time equals caloric intake minus caloric expenditure — true at the thermodynamic level, hard to execute on.Sat, 18 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/weekly-average-weight/https://nutritiondex.com/glossary/weekly-average-weight/The rolling 7-day mean of daily body-weight readings — the smoothed signal that reveals true body-composition trajectory under daily noise.Sat, 18 Apr 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/protein/https://nutritiondex.com/glossary/protein/The macronutrient providing amino acids for tissue synthesis, enzyme production, and metabolic signalling — yielding 4 kcal per gram with an elevated thermic effect of 20-30%.Fri, 17 Apr 2026 00:00:00 GMTmacronutrient-scienceMarcus Chenhttps://nutritiondex.com/glossary/macronutrients/https://nutritiondex.com/glossary/macronutrients/The three energy-yielding nutrients consumed in gram-scale quantities: protein, carbohydrate, and fat. Alcohol is sometimes treated as a fourth.Thu, 16 Apr 2026 00:00:00 GMTmacronutrient-scienceMarcus Chenhttps://nutritiondex.com/glossary/maintenance-calories/https://nutritiondex.com/glossary/maintenance-calories/The caloric intake at which body weight remains stable over time — equal to TDEE by definition, and the anchor from which deficits and surpluses are calculated.Wed, 15 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/calorie-deficit/https://nutritiondex.com/glossary/calorie-deficit/A state in which caloric intake is lower than caloric expenditure over a sustained window — the driver of fat loss when other conditions are held stable.Tue, 14 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/energy-expenditure/https://nutritiondex.com/glossary/energy-expenditure/The total caloric cost of all physiological processes and activities over a given period — the "out" side of the calories-in-calories-out equation.Mon, 13 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/tef/https://nutritiondex.com/glossary/tef/The energy cost of digesting, absorbing, and storing food — roughly 10% of total intake on a mixed diet and substantially higher for protein.Sun, 12 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/neat/https://nutritiondex.com/glossary/neat/Calories burned from all daily movement that is not deliberate exercise — walking, standing, fidgeting, chores — often varying by 800-1000 kcal/day between individuals.Sat, 11 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/bmr/https://nutritiondex.com/glossary/bmr/The minimum energy a body expends at complete rest to maintain vital functions — measured under strict fasting and thermoneutral conditions.Fri, 10 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/rmr/https://nutritiondex.com/glossary/rmr/Energy expended at rest under non-strict conditions — typically 5-10% higher than true BMR and the value most consumer tools actually estimate.Thu, 09 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/calorie-surplus/https://nutritiondex.com/glossary/calorie-surplus/A state in which caloric intake exceeds caloric expenditure — the driver of weight gain, whether that gain is predominantly muscle or predominantly fat.Wed, 08 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/thermogenesis/https://nutritiondex.com/glossary/thermogenesis/The production of heat in the body — the biophysical mechanism underlying BMR, TEF, NEAT, and exercise energy expenditure.Tue, 07 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/metabolic-flexibility/https://nutritiondex.com/glossary/metabolic-flexibility/The ability to efficiently switch between carbohydrate and fat as primary fuel sources in response to metabolic demand.Mon, 06 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/carbohydrates/https://nutritiondex.com/glossary/carbohydrates/The macronutrient composed of sugars, starches, and fibres — yielding 4 kcal per gram and the body's preferred fuel for high-intensity exercise.Sun, 05 Apr 2026 00:00:00 GMTmacronutrient-scienceMarcus Chenhttps://nutritiondex.com/glossary/metabolic-adaptation/https://nutritiondex.com/glossary/metabolic-adaptation/The umbrella term for the cluster of physiological changes that reduce total energy expenditure below predicted levels during and after sustained caloric deficit.Sat, 04 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/adaptive-thermogenesis/https://nutritiondex.com/glossary/adaptive-thermogenesis/The specific reduction in energy expenditure beyond what fat-free-mass loss alone would predict, observed during and after sustained caloric deficit.Sat, 04 Apr 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/cutting/https://nutritiondex.com/glossary/cutting/A deliberate, time-bounded caloric deficit intended to reduce body fat while preserving lean mass — the fat-loss phase of a periodised nutrition plan.Fri, 03 Apr 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/bulking/https://nutritiondex.com/glossary/bulking/A deliberate, time-bounded caloric surplus intended to gain muscle mass — paired with progressive resistance training and high protein intake.Thu, 02 Apr 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/fats/https://nutritiondex.com/glossary/fats/The most energy-dense macronutrient at 9 kcal per gram — essential for hormone synthesis, membrane structure, and fat-soluble vitamin absorption.Wed, 01 Apr 2026 00:00:00 GMTmacronutrient-scienceMarcus Chenhttps://nutritiondex.com/glossary/satiety/https://nutritiondex.com/glossary/satiety/The physiological signal that suppresses further food intake between meals — distinct from satiation, which ends a single meal.Tue, 31 Mar 2026 00:00:00 GMTbiochemistryMarcus Chenhttps://nutritiondex.com/glossary/glycemic-index/https://nutritiondex.com/glossary/glycemic-index/A 0-100 scale ranking how rapidly and how high a carbohydrate-containing food raises blood glucose relative to a reference (pure glucose = 100).Mon, 30 Mar 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/energy-balance/https://nutritiondex.com/glossary/energy-balance/The relationship between caloric intake and caloric expenditure over a defined period — negative (deficit), neutral (maintenance), or positive (surplus).Sun, 29 Mar 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/recomposition/https://nutritiondex.com/glossary/recomposition/The simultaneous reduction of fat mass and increase in lean mass at roughly maintenance calories — most achievable in untrained, overweight, or detrained populations.Sat, 28 Mar 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/glycemic-load/https://nutritiondex.com/glossary/glycemic-load/The portion-corrected version of glycemic index: GL = GI × grams of available carbohydrate ÷ 100. A more practical predictor of real-meal glucose response.Fri, 27 Mar 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/ghrelin/https://nutritiondex.com/glossary/ghrelin/The "hunger hormone" secreted primarily by the stomach, rising before meals and after weight loss to drive appetite and food-seeking behaviour.Thu, 26 Mar 2026 00:00:00 GMTbiochemistryMarcus Chenhttps://nutritiondex.com/glossary/leptin/https://nutritiondex.com/glossary/leptin/The "satiety hormone" secreted by adipose tissue in proportion to fat mass, signalling long-term energy availability to the hypothalamus.Wed, 25 Mar 2026 00:00:00 GMTbiochemistryMarcus Chenhttps://nutritiondex.com/glossary/insulin-sensitivity/https://nutritiondex.com/glossary/insulin-sensitivity/The efficiency with which cells respond to insulin — higher sensitivity means less insulin needed to achieve a given glucose-lowering effect.Mon, 23 Mar 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/fiber/https://nutritiondex.com/glossary/fiber/The non-digestible carbohydrate component of plant foods — effectively contributing 0-2 kcal per gram and supporting satiety, glycemic response, and gut function.Sun, 22 Mar 2026 00:00:00 GMTmacronutrient-scienceMarcus Chenhttps://nutritiondex.com/glossary/net-carbs/https://nutritiondex.com/glossary/net-carbs/A tracking convention where fiber (and sometimes sugar alcohols) are subtracted from total carbohydrate to reflect the glucose-raising fraction — popular in low-carb and ketogenic contexts.Fri, 20 Mar 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/refeed/https://nutritiondex.com/glossary/refeed/A structured single-day or short-duration increase in caloric intake (typically from carbohydrates) during an ongoing deficit, intended to temporarily restore glycogen, leptin, and performance.Thu, 19 Mar 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/diet-break/https://nutritiondex.com/glossary/diet-break/A planned multi-day period (usually 7-14 days) at maintenance calories within a longer cut, intended to partially reverse adaptive thermogenesis and support adherence.Wed, 18 Mar 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/reverse-dieting/https://nutritiondex.com/glossary/reverse-dieting/A structured, gradual increase in caloric intake following a cut, aimed at returning to maintenance without rapid fat regain.Tue, 17 Mar 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/insulin-resistance/https://nutritiondex.com/glossary/insulin-resistance/A reduced responsiveness of cells to insulin, requiring the pancreas to produce more insulin to achieve the same glucose-lowering effect — the central defect in type 2 diabetes.Sun, 15 Mar 2026 00:00:00 GMTmetabolic-physiologyMarcus Chenhttps://nutritiondex.com/glossary/body-composition/https://nutritiondex.com/glossary/body-composition/The proportional breakdown of body mass into fat mass, lean mass (muscle, bone, organs), and water — a more informative metric than total body weight for health and fitness.Fri, 13 Mar 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/body-fat-percentage/https://nutritiondex.com/glossary/body-fat-percentage/Fat mass expressed as a percentage of total body mass — a headline metric for body composition, with accuracy heavily dependent on measurement method.Wed, 11 Mar 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/lean-body-mass/https://nutritiondex.com/glossary/lean-body-mass/Total body mass minus fat mass — everything non-fat: muscle, bone, organs, connective tissue, and body water.Sun, 08 Mar 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/water-weight/https://nutritiondex.com/glossary/water-weight/Body mass variation caused by hydration state and fluid retention rather than true tissue change — responsible for most daily scale-weight fluctuation.Fri, 06 Mar 2026 00:00:00 GMTdietary-assessmentMarcus Chenhttps://nutritiondex.com/glossary/glycogen-stores/https://nutritiondex.com/glossary/glycogen-stores/The body's stored carbohydrate reserve — 300-600 g held in muscle and liver as glycogen, rapidly mobilised for high-intensity exercise and short-term energy needs.Thu, 05 Mar 2026 00:00:00 GMTmetabolic-physiologyMarcus Chen