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Calorie and Nutrition Terms: A Plain-English Glossary

October 14, 2026 · Viral Tandel

Calorie and nutrition tracking comes with its own small vocabulary, and a lot of it gets used casually without ever being defined. This calorie and nutrition glossary collects the terms that come up most often on this site and in any calorie counting app, in plain English, with a link to a fuller explanation wherever one exists.

Nothing here is dosage advice or a specific number to hit. Where a term has an exact formula, like BMR, that formula is given. Where a term is more of a concept, like a macro split, it is explained as a concept rather than handed a made-up default number.

Key takeaways

• A Calorie on a food label and a kcal are the same unit; food labels just capitalize it.
• BMR is a resting baseline. TDEE is BMR plus activity, and is the number most people actually want day to day.
• Net carbs is a term KalTrack does not calculate. It logs total carbohydrate and fiber separately instead.
• A macro split divides a calorie target you already have into protein, carbohydrate and fat. It is a separate step from setting the calorie target itself.
• Terms like serving size and portion size get used interchangeably in speech but mean different things on a label, and the gap between them is a common source of tracking errors.

Energy terms

Calorie. A unit of energy. On a US or Canadian nutrition label, one Calorie (capitalized) is actually a kilocalorie, one thousand of the small scientific calories used in a chemistry class. Nutrition tracking almost always means the capitalized, food-label version, and this site writes it as kcal to keep that clear. For the full explanation of why the two labels exist for the same unit, see kcal vs calories.

BMR (basal metabolic rate). The energy your body burns at complete rest: heartbeat, breathing, organ function, and nothing else. It is a baseline, not a target to eat at. See what is BMR for the formula this site's calculators use and a worked example.

TDEE (total daily energy expenditure). BMR multiplied by an activity level, giving an estimate of what you burn across a full day including movement and exercise. This is usually the more practical number for planning meals. The TDEE calculator walks through picking an activity level that actually matches your week.

Maintenance calories. Another name for TDEE, used specifically when the point being made is that eating this amount should, on average, keep your weight roughly stable over time.

Calorie deficit. Eating fewer calories than your TDEE, so that your body draws on stored energy to make up the difference. See what is a calorie deficit for how that translates into an eating target and what a realistic pace of change looks like.

Calorie surplus. The opposite of a deficit: eating more calories than your TDEE, typically the target when the goal is gaining weight rather than losing it.

Macronutrient terms

Macronutrients, or macros. The three nutrients that carry calories: protein, carbohydrate and fat. Alcohol also carries calories but is not usually counted as a macronutrient in a tracking app. "Macros" in casual use almost always means these three.

Protein. The macronutrient built from amino acids, used for building and repairing tissue among other roles. Tracked in grams, and often the macro people pay closest attention to when a fitness goal is involved.

Carbohydrate. The macronutrient that includes sugars, starches and fiber. A food's total carbohydrate figure on a label includes all of these together, not sugar alone.

Fat. The macronutrient with the highest energy density of the three, tracked in grams like the other two. "Fat" on a label is total fat, which includes several sub-types, saturated fat among them, broken out as their own lines beneath it.

Fiber. The part of total carbohydrate that the body does not fully digest. It is usually listed as its own line beneath total carbohydrate on a label rather than subtracted from it.

Net carbs. Total carbohydrate minus fiber, sometimes minus certain sugar alcohols as well, used mainly in low-carb and keto tracking. This is a term worth defining carefully because it is not a standardized label value: different sources calculate it slightly differently. KalTrack does not calculate or display net carbs; it logs total carbohydrate and fiber as separate figures, and does not offer a keto-specific mode.

Macro split, or macro targets. The division of a calorie target into grams of protein, carbohydrate and fat, usually expressed as either grams or a percentage of total calories. Setting a macro split is a separate step that comes after a calorie target is set, not a replacement for one. Setting macro targets covers how that decision typically gets made.

Label and portion terms

Serving size. The specific amount a nutrition label's figures describe, defined by the manufacturer or by a standard reference amount. It is not automatically the amount you actually ate.

Portion size. The amount you actually put on your plate or in your bowl. Portion size and serving size are used interchangeably in everyday speech, but a food's label always describes the serving size, and the two frequently do not match. Logging three servings when you only measured one portion, or the reverse, is one of the most common ways a correct-looking label figure turns into a wrong logged total.

Sodium. A mineral tracked on nutrition labels separately from the three macronutrients, commonly monitored for blood pressure reasons. KalTrack logs calories, protein, carbohydrate and fat; it does not currently track sodium or other micronutrients.

Added sugar versus total sugar. Total sugar on a label includes everything naturally present in the food plus anything added during preparation. Added sugar, listed as its own line beneath it, is only the sugar that was mixed in, not what the food started with. A plain yogurt and a flavored one can have very different added sugar even with similar total sugar.

Tracking and database terms

Food database. The underlying set of entries a tracking app searches when you look up a food by name. Databases vary enormously in size, accuracy and how well they cover food outside of American supermarket products, which is exactly the gap this site's own USDA-sourced figures are built to be honest about.

Crowd-sourced database. A food database built from entries submitted by users or by manufacturers themselves, such as Open Food Facts, rather than compiled and verified by a single authority. A crowd-sourced database can cover far more packaged products, especially internationally, than a government database ever could, but any individual entry only carries as much accuracy as whoever submitted it.

FDC ID. The unique identifier USDA FoodData Central assigns to each entry in its database. This site cites the FDC ID behind every sourced food figure it publishes, specifically so a reader can look up the original entry rather than take a number on faith.

Barcode lookup. Scanning a packaged food's barcode to retrieve the manufacturer's own published nutrition figures, rather than estimating from a photo. It is generally the most precise logging method available for anything that comes in a package, because it reads the maker's own numbers rather than inferring them.

Nutrition label OCR. Reading the printed nutrition panel on a package with a camera, using optical character recognition, rather than looking the product up by barcode. Useful for foods without a barcode in a given database, or without a barcode at all.

AI photo estimate. A calorie and macro estimate generated from a photograph of a meal, rather than from a barcode or label. It is the most flexible logging method, since it works on homemade and restaurant food that has no barcode, and also the least precise, since it is inferring quantity and ingredients from an image rather than reading them from a package.

Margin of error. How far a photo estimate can reasonably be expected to land from the true figure. Every estimation method has one; a photo estimate's margin is wider than a barcode's, since a barcode is reading a published number rather than inferring one.

Weight and progress terms

Weight trend. A rolling average of daily weigh-ins, used instead of any single day's number because body weight naturally moves up and down from water, sodium and digestion, not only from fat or muscle change. A trend line smooths that day-to-day noise out and is generally a more honest signal of real progress than one morning's reading.

Water weight. Short-term weight change caused by the body holding more or less water, rather than a change in fat or muscle. Sodium intake, carbohydrate intake and hormonal cycles are common causes. It can move the scale more in a single day than fat loss typically does across a whole week, which is exactly why judging progress from one day's weight is unreliable.

Plateau. A stretch where weight stops changing despite no obvious change in eating or activity. It is usually explained by TDEE quietly shifting as body weight changes, by water weight temporarily masking real progress, or by ordinary variation, rather than by a deficit suddenly "stopping working."

Diet approach terms

Cutting. Informal shorthand for eating in a calorie deficit with the specific goal of losing fat while trying to keep muscle, usually paired with resistance training and a comparatively higher protein target.

Bulking. The opposite: eating in a calorie surplus with the goal of gaining muscle, usually also paired with resistance training.

Recomposition, or recomp. Trying to lose fat and gain muscle over the same stretch of time, typically eaten close to maintenance calories rather than a clear deficit or surplus. It tends to work best for people newer to resistance training and is generally slower and less predictable than a dedicated cut or bulk.

Keto. A very low carbohydrate, higher fat way of eating, named for the metabolic state, ketosis, it is intended to produce. KalTrack does not offer a keto-specific mode or calculate net carbs, so anyone tracking strictly for keto would need to watch total carbohydrate and fiber manually against their own target.

Whole food. A term used loosely to mean food close to its original form, an apple rather than apple juice concentrate, chicken breast rather than a breaded chicken product. It has no single official definition or cutoff, which is worth knowing before treating any app's "whole food score" as more precise than it actually is.

Ultra-processed food. Food manufactured with ingredients and methods not typically used in a home kitchen, industrial additives among them. Like "whole food," the term is genuinely useful for describing a pattern of eating, but it is a spectrum rather than a strict yes-or-no label, and two people can draw the line in different places for the same product.

Using this glossary alongside the rest of the site

None of these terms are useful in isolation. A calorie deficit only means something once you know your TDEE; a macro split only means something once you have a calorie target to divide. The calorie calculators guide walks through how BMR, TDEE, deficit and macro calculators connect to each other in the order you would actually use them.

Where this glossary cannot help is the other half of tracking: knowing what you actually ate. A perfectly defined macro split does nothing for you if the log underneath it is missing the oil a dish was cooked in or double-counting a serving size. Try logging a real meal in KalTrack and see how the terms above show up in an actual entry, protein, carbs and fat broken out per food, rather than just in a definition.

This is general information about tracking food, not medical advice. If you are managing a health condition or working to a clinical target, talk to your doctor or a registered dietitian before changing how you eat.