| Term | Acronym | Definition |
|---|---|---|
| AMPK | — | AMP-activated protein kinase — cellular energy sensor activated by exercise, fasting, metformin, berberine. |
| Apolipoprotein B (ApoB) | — | Particle count of all atherogenic lipoproteins — superior single marker for cardiovascular risk vs. LDL-C alone. |
| Autophagy | — | Cellular self-cleaning of damaged proteins and organelles. Activated by fasting, exercise, mTOR inhibition, spermidine. |
| Bioavailability | — | Fraction of an ingested dose that reaches systemic circulation. |
| BPC-157 | — | Body-Protective Compound 15-aa. Pentadecapeptide from gastric juice protein. |
| Cmax / Cmin / Css | — | Peak / trough / steady-state concentration. |
| CGM | — | Continuous glucose monitor. |
| Compounded medication | — | Drug prepared by a pharmacy for an individual patient. |
| DEXA | — | Dual-energy X-ray absorptiometry; gold-standard body composition scan. |
| DHA / EPA | — | Long-chain omega-3 fatty acids. |
| Down-regulation | — | Decrease in receptor density or sensitivity in response to chronic ligand exposure. |
| EFSA | — | European Food Safety Authority. |
| Endocrine disruptor | — | Compound that interferes with hormone signaling. BPA, phthalates, atrazine. |
| Estradiol (E2) | — | Primary estrogen. Critical in men at 20-30 pg/mL. |
| FAO/WHO | — | Reference for international activity multipliers in BMR equations. |
| Ferritin | — | Iron-storage protein. Reflects body iron status. |
| GHK-Cu | — | Copper-binding tripeptide. Skin remodeling, wound healing. |
| GIP | — | Glucose-dependent insulinotropic polypeptide. Half of tirzepatide. |
| GLP-1 | — | Glucagon-like peptide-1. Slows gastric emptying, suppresses appetite. |
| Glycemic variability | — | Swing magnitude in glucose readings. CGM metric. |
| HbA1c | — | Glycated hemoglobin. Average glucose over ~3 months. |
| Half-life (t1/2) | — | Time for plasma concentration to fall by half. |
| HOMA-IR | — | Insulin resistance index calculated from fasting insulin and glucose. |
| HRV | — | Heart rate variability. Proxy for autonomic balance. |
| Hyaluronic acid | — | Glycosaminoglycan in skin, joints, eyes. |
| HPG axis | — | Hypothalamic-pituitary-gonadal axis. |
| IGF-1 | — | Insulin-like growth factor 1. Downstream of GH. |
| Incretin | — | Hormone (GLP-1, GIP) released by gut after food. |
| Intermittent fasting | — | Time-restricted eating: 16:8, 18:6, 24h. |
| IRB | — | Institutional Review Board overseeing human research. |
| IU | — | International unit. Activity-based dosing unit. |
| Kisspeptin | — | Hypothalamic peptide; master regulator of GnRH. |
| L-theanine | — | Amino acid in tea. Calm focus. |
| Lipid panel | — | Total cholesterol, LDL-C, HDL-C, triglycerides. |
| Lp(a) | — | Lipoprotein(a). Genetic, modifiable only modestly. |
| MK-7 | — | Menaquinone-7. Long half-life form of K2. |
| MOTS-c | — | Mitochondrial-derived peptide. |
| mTOR | — | Mechanistic target of rapamycin. Master nutrient-sensor. |
| NAD+ | — | Nicotinamide adenine dinucleotide. Coenzyme central to redox. |
| NMN / NR | — | NAD+ precursors. |
| Off-label use | — | Prescribing an FDA-approved drug outside its labeled indication. |
| Omega-3 index | — | RBC EPA+DHA as % of total fatty acids. Target ≥8%. |
| Pharmacokinetics (PK) | — | What the body does to a drug. |
| Pharmacodynamics (PD) | — | What the drug does to the body. |
| PPI | — | Proton pump inhibitor. |
| RCT | — | Randomized controlled trial. |
| Reverse T3 (rT3) | — | Inactive thyroid hormone. |
| SC injection | — | Subcutaneous. Standard for GLP-1s and most peptides. |
| SHBG | — | Sex hormone-binding globulin. |
| SIBO | — | Small intestinal bacterial overgrowth. |
| Sirtuins | — | NAD+-dependent enzymes modulating gene expression. |
| Statin | — | HMG-CoA reductase inhibitor; cholesterol-lowering. |
| TDEE | — | Total daily energy expenditure. |
| Therapeutic window | — | Range between effective and toxic dose. |
| Titration | — | Gradual dose increase to find tolerable effective level. |
| TSH | — | Thyroid-stimulating hormone. |
| TRT | — | Testosterone replacement therapy. |
| Urolithin A | — | Metabolite of ellagitannins. Mitophagy inducer. |
| UV index | — | Sunburn intensity scale 0-11+. |
| VAT | — | Visceral adipose tissue. Metabolically active, inflammatory. |
| Vitamin D (25-OH-D) | — | Storage form measured. Target 40-60 ng/mL. |
| VO2 max | — | Maximal oxygen uptake. Strong mortality predictor. |
| Wash-out | — | Time required after stopping a drug for plasma levels to fall to negligible. |
| Zone 2 | — | Aerobic intensity at conversational pace; mitochondrial training zone. |
| DMAE | — | Dimethylaminoethanol; older choline-adjacent nootropic. |
| Bilirubin | — | Heme breakdown product. Elevation: Gilbert's, hemolysis, hepatic. |
Definitions are concise on purpose. For deeper coverage, follow cross-references to topic hubs and drug profiles. If a term is missing that you've seen referenced here, write back via the newsletter and it'll get added.