Calorie & Nutrition Glossary
Plain-English definitions for calorie counting, metabolism, macros, and weight loss concepts. Browse the A–Z index below.
Want to calculate your personal targets? Start at our calorie calculator.
4
- 4-4-9 RuleA quick way to estimate calories from macros: carbs (4), protein (4), fat (9) calories per gram.
A
- Activity FactorA multiplier used to scale BMR up to estimate TDEE based on daily activity level.
B
- Basal Metabolic Rate (BMR)The calories your body burns at rest to support basic life functions.
- Body Fat PercentageThe percentage of your total body weight that comes from fat mass.
C
- CalorieA unit of energy in food and activity. In nutrition, “calorie” usually means a kilocalorie (kcal).
- Calorie DeficitEating fewer calories than you burn, which can lead to weight loss over time.
- Calorie DensityCalories per unit of food volume or weight—higher density means more calories in less food.
- Calorie SurplusEating more calories than you burn, which can lead to weight gain over time.
- CarbohydratesA macro that fuels activity and can affect glycogen and water weight.
D
- Diet BreakA planned period of eating closer to maintenance to reduce fatigue and improve adherence.
- Dietary FatA calorie-dense macro (about 9 calories per gram) important for hormones and nutrient absorption.
E
- Energy BalanceThe relationship between calories consumed and calories burned over time.
- Exercise CaloriesCalories burned during planned workouts, often estimated using METs or wearable devices.
F
- FiberA carbohydrate component that supports digestion and can improve fullness with fewer calories.
- Food ScaleA tool that improves tracking accuracy by measuring food weight instead of guessing.
G
- GlycogenStored carbohydrate in muscle and liver that holds water and impacts short-term scale weight.
H
- Harris–Benedict EquationAn older BMR formula that estimates baseline calorie burn from body stats.
K
- Katch–McArdle FormulaA BMR formula that uses lean body mass, often requiring a body fat estimate.
L
- Lean Body MassEverything in your body that isn’t fat: muscle, bone, organs, and water.
M
- Macronutrients (Macros)Protein, carbohydrates, and fats—the nutrients that provide calories.
- Maintenance CaloriesThe calorie intake that tends to keep body weight stable (often close to TDEE).
- MET (Metabolic Equivalent of Task)A value used to estimate calories burned during activities based on intensity.
- Metabolic AdaptationA reduction in calorie burn that can occur during prolonged dieting or weight loss.
- Mifflin–St Jeor EquationA widely used BMR formula based on sex, age, height, and weight.
N
- NEAT (Non-Exercise Activity Thermogenesis)Calories burned from movement that isn’t formal exercise, like walking and chores.
P
- Portion SizeThe amount of food you eat in one sitting, which can differ from a labeled serving size.
- ProteinA macro that supports muscle repair, satiety, and has a higher thermic effect than other macros.
S
- SatietyThe feeling of fullness that reduces the urge to keep eating.
T
- Thermic Effect of Food (TEF)The calories your body burns to digest, absorb, and process food.
- Total Daily Energy Expenditure (TDEE)Your total calories burned per day from BMR, movement, exercise, and digestion.
W
- Water WeightShort-term scale changes caused by fluid shifts rather than fat gain or loss.