Calorie tracking, in plain English.

BMR (Basal Metabolic Rate)

The energy your body uses at complete rest — heart, brain, organs, cell turnover. Roughly 60–75% of total daily energy.

BMR is estimated by formulas like Mifflin-St Jeor (the modern default) or Harris-Benedict (older, slightly less accurate). Both take height, weight, age and sex as inputs. Lab-measured BMR via indirect calorimetry is more accurate but rarely accessible.

TDEE (Total Daily Energy Expenditure)

BMR × an activity multiplier — your full daily calorie burn.

TDEE = BMR × activity factor (typically 1.2 sedentary, 1.375 light, 1.55 moderate, 1.725 very active). Adaptive trackers like MacroFactor recalculate yours weekly from actual scale-weight changes.

Related: BMR (Basal Metabolic Rate), NEAT (Non-Exercise Activity Thermogenesis)

NEAT (Non-Exercise Activity Thermogenesis)

All movement that isn't planned exercise — fidgeting, walking the dog, standing at a desk. The most variable part of TDEE.

NEAT is the reason two people with the same BMR and workout can have a 500-kcal/day TDEE gap. It also drops when you cut calories — your body fidgets less, walks more slowly, and conserves energy.

EAT (Exercise Activity Thermogenesis)

Calories burned during planned exercise.

Wearables systematically over-estimate EAT. We recommend treating wearable-reported burn as a ceiling, not a floor.

TEF (Thermic Effect of Food)

The energy your body spends digesting food. Roughly 10% of total intake; protein has the highest TEF (~25%).

Why high-protein diets feel slightly less calorie-dense — you net fewer calories from a 200-kcal portion of chicken than from 200 kcal of olive oil.

RDA (Recommended Dietary Allowance)

The daily intake of a nutrient sufficient to meet the needs of 97.5% of healthy people.

Set by the National Academies of Sciences, Engineering, and Medicine. RDAs are not optimal-performance targets — they're deficiency-prevention floors.

DV (Daily Value)

The percentages you see on a US Nutrition Facts label, derived from RDAs.

DVs are based on a 2,000-kcal reference diet. Your actual daily targets may be higher or lower depending on size, activity and goals.

Macros (Macronutrients)

Protein, carbohydrate and fat — the three sources of calories in food. Sometimes alcohol is counted as a fourth.

Calories per gram: protein 4, carbs 4, fat 9, alcohol 7. CalorieScan AI surfaces all three by default.

Micros (Micronutrients)

Vitamins and minerals. Don't supply calories, but deficiencies have outsized effects.

The most commonly tracked micros are iron, B12, omega-3, calcium, vitamin D, magnesium and zinc. CalorieScan AI surfaces 12 in the weekly review.

GLP-1 (Glucagon-Like Peptide-1)

A hormone that suppresses appetite. The class of medications (Ozempic, Wegovy, Mounjaro, Zepbound) that mimic it.

GLP-1 medications shift the failure mode of weight management from over-eating to under-eating, which is why CalorieScan AI ships a dedicated GLP-1 mode that flips the framing. See /for/glp-1.

Sarcopenia

Age-related loss of skeletal muscle. Accelerates after 50.

Best prevented with adequate protein (~1.2 g/kg bodyweight) and resistance training. CalorieScan AI's adults-50+ default raises the protein floor accordingly.

Cut / Bulk / Maintenance

Three goal modes: lose fat, gain muscle, hold steady.

Cuts are typically a 10–25% calorie deficit; bulks are a 5–15% surplus; maintenance is at TDEE. Most lifters cycle through all three over a year.

MAPE (Mean Absolute Percent Error)

How far off, on average, an estimate is from the truth. Used to measure photo-recognition accuracy.

If your app reports 600 kcal for a 500-kcal meal, that's 20% absolute error. MAPE averages this across many plates. Our current first-pass MAPE is ~17%, which we round to '~80% accuracy'.

FoodData Central

USDA's canonical nutrition database — the source of truth for whole-food macros in the US.

Combines four older databases (SR Legacy, Foundation Foods, Branded Foods, FNDDS). Most reputable trackers, including CalorieScan AI, source from it.

OpenFoodFacts

An open, community-edited database of packaged products. Covers most barcodes globally.

Quality varies — community submissions can have errors — but coverage is unmatched and the data is openly licensed.

Hreflang

An HTML tag that tells search engines which language and region a page targets.

Used when you have multiple localized versions of the same page. Not relevant to single-language sites.