Glossary — The Body Calculator

Body composition

BMI: Body Mass Index. Weight in kilos divided by height in metres, squared. It's a coarse screen — fine at population level, less useful if you're heavily muscled or have an unusual frame.
BMR: Basal Metabolic Rate. The calories your body burns just keeping the lights on: heartbeat, breathing, keeping warm. Usually 60–75% of your total daily energy use.
TDEE: Total Daily Energy Expenditure. BMR multiplied by an activity factor. The number you eat against if you're tracking weight.
BSA: Body Surface Area. Square metres of skin. Hospitals use it to dose chemo and IV fluids — not relevant for weight loss.
WHR: Waist-to-Hip Ratio. Waist divided by hip. Tracks cardiometabolic risk better than BMI for a lot of people.
IBW: Ideal Body Weight. A reference number from older formulas (Devine, Robinson, Miller). Mostly used in pharmacology to dose drugs that distribute through lean tissue.
LBM / FFM: Lean Body Mass / Fat-Free Mass. Your body weight minus the fat. Mostly muscle, bone, organs, and water.

SBP / DBP: Systolic / Diastolic Blood Pressure. The two numbers in a blood pressure reading. Systolic is the high one (heart contracting), diastolic the low one (heart relaxing).
MAP: Mean Arterial Pressure. A weighted average of SBP and DBP that approximates the pressure your organs actually see. 70–100 mmHg is the healthy range.
Pulse pressure: Simply SBP − DBP. A wide pulse pressure in older adults is often a sign of stiff arteries.
LDL: Low-Density Lipoprotein. The "bad" cholesterol — higher levels track with cardiovascular events.
HDL: High-Density Lipoprotein. The "good" cholesterol — higher is better.
Triglycerides: Fat circulating in your blood. High levels tend to ride along with insulin resistance and metabolic syndrome.
ASCVD: Atherosclerotic Cardiovascular Disease. Umbrella term for the conditions that plaque build-up causes: heart attack, stroke, peripheral artery disease.
AF / AFib: Atrial Fibrillation. An irregular heart rhythm. A major cause of stroke when left untreated.
CHA₂DS₂-VASc: A 0–9 score that predicts stroke risk in someone with non-valvular AF. Clinicians use it to decide whether to start anticoagulation.

HbA1c: Glycated haemoglobin. Reflects your average blood sugar over the past ~3 months. The headline number for diagnosing and tracking diabetes.
eAG: Estimated Average Glucose. HbA1c translated back into the glucose number you'd see on a finger-stick meter.
HOMA-IR: Homeostatic Model Assessment — Insulin Resistance. A single-draw estimate of how sensitive your tissues are to insulin. Below 1.9 is generally healthy.
TyG: Triglyceride-Glucose index. A cheap proxy for insulin resistance when fasting insulin wasn't measured.
eGFR: Estimated Glomerular Filtration Rate. How well your kidneys filter blood. Below 60 mL/min/1.73m² for three months meets the definition of chronic kidney disease.
CKD: Chronic Kidney Disease. Staged G1 (mildest) through G5 (kidney failure) by eGFR.
AST & ALT: Liver enzymes (aspartate aminotransferase, alanine aminotransferase). Released into the blood when liver cells are stressed.
FIB-4: A non-invasive estimate of advanced liver fibrosis built from age, AST, ALT, and platelet count.
NAFLD: Non-Alcoholic Fatty Liver Disease. The most common chronic liver disease worldwide; very tied to metabolic syndrome and obesity.

HR: Heart rate, in beats per minute.
HRmax: Your estimated maximum heart rate. The Tanaka formula (208 − 0.7 × age) is a better estimate than the old "220 − age" rule for adults.
HRrest: Resting heart rate. Take it first thing in the morning, lying still, before you check your phone.
HRR: Heart Rate Reserve — HRmax − HRrest. The Karvonen formula uses it to set training-zone intensities.
VO₂max: Maximum oxygen uptake while exercising at full tilt. One of the strongest predictors of aerobic fitness and all-cause mortality.
1RM: One-Repetition Maximum. The heaviest weight you can lift once with good form. Most calculators (including ours) estimate it from a multi-rep set so you don't have to actually try a true single.
MET: Metabolic Equivalent. 1 MET ≈ the energy you use sitting quietly. A 6-MET activity uses six times as much.

SI units: Système International. The metric-based standard most labs and most countries use: mmol/L for cholesterol and glucose, µmol/L for creatinine.
US conventional units: mg/dL for cholesterol, glucose, and creatinine. Common in the United States; less so elsewhere.
mmHg: Millimetres of mercury. The pressure unit on blood-pressure cuffs.
bpm: Beats per minute. Heart rate.
mIU/L: Milli-international units per litre. How fasting insulin is reported in most labs.
U/L: Units per litre. The standard reporting unit for liver enzymes and similar.

Missing a term? Drop me a line and I'll add it.