| Term | Aliases | Category | Definition |
|---|---|---|---|
| AMPK | AMP-activated protein kinase | Concept | The cell's low-energy alarm. Triggered by exercise, fasting, metformin, and berberine — it pushes the body to burn stored energy and slow growth pathways. Most longevity protocols touch AMPK either directly or via caloric restriction. |
| Andrew Huberman | Huberman | Researcher | Stanford neuroscientist and host of Huberman Lab. Popularized morning sunlight, cold exposure, and neurochemistry-based protocols. Audience reach is enormous; protocol specifics often outrun the human evidence base. |
| Apolipoprotein B | ApoB · apo B | Biomarker | Count of every atherogenic particle in your blood. Most cardiologists who follow the data treat ApoB as a better single number for heart-disease risk than LDL-C. Target <90 mg/dL for general health, <60 for prevention. |
| AUC | area under the curve | Pharmacology | Total drug exposure over time — the area under the plasma-concentration curve. Two drugs with the same Cmax can have very different AUCs and very different effects. The number regulators care about. |
| Autophagy | self-eating | Concept | Cellular spring cleaning — old proteins and damaged organelles get recycled. Activated by fasting, hard exercise, mTOR inhibition, spermidine. Won the 2016 Nobel; commercial claims have outrun the human evidence. |
| Bilirubin | — | Biomarker | Heme breakdown product. Mild elevation often Gilbert's syndrome (benign). Significant elevation: hemolysis or liver issue. Reads on a standard metabolic panel — most people never know they ran one. |
| Bioavailability | F | Pharmacology | Percentage of a dose that actually reaches your bloodstream intact. Oral peptides usually <5%. IV is 100% by definition. Why some compounds require injection — and why oral versions of injectable drugs are not interchangeable. |
| BPC-157 | Body Protective Compound 157 · pentadecapeptide | Drug / molecule | 15-amino-acid fragment originally isolated from gastric juice. Strong rodent data on tendon and gut healing; almost no human RCTs. Popular off-label for soft-tissue injuries; legality varies by country. |
| Casey Means | Means | Researcher | ENT-trained physician; co-founder of Levels (CGM startup). Vocal critic of metabolic dysfunction as the root of chronic disease. Strong on framing; the commercial CGM angle colors recommendations. |
| CGM | continuous glucose monitor · Dexcom · Libre | Biomarker | Skin patch that reads interstitial glucose every few minutes. Diabetics need it. Non-diabetics get useful pattern data for ~2 weeks; longer use mostly drives anxiety about benign post-meal spikes. |
| Cmax / Cmin / Css | peak concentration · trough · steady state | Pharmacology | Cmax = peak drug level after a dose. Cmin = trough before the next. Css = steady-state once dosing is regular. These shape side effects and efficacy more than total daily dose. |
| Cochrane review | Cochrane Collaboration | Study design | Independent network producing systematic reviews and meta-analyses. The closest thing medicine has to a referee. When a Cochrane review and an industry-funded review disagree, default to Cochrane. |
| Compounded medication | compound pharmacy | Drug / molecule | Drug mixed by a pharmacy for a specific patient — typically when commercial supply runs short. Quality varies sharply by source. The compounded-GLP-1 wave shrank dramatically once shortages ended in 2025. |
| Dale Bredesen | Bredesen | Researcher | Neurologist; developer of the ReCODE protocol for cognitive decline. Single-arm studies show signal; lack of RCTs is the persistent critique. Influential in functional-medicine Alzheimer's care. |
| David Sinclair | Sinclair | Researcher | Harvard biologist; co-founder of multiple longevity ventures. Authored Lifespan. Original NAD+ / sirtuin / NMN narrative came largely from his lab. Influential and frequently overinterpreted — human translation has lagged the mouse data. |
| DEXA | DXA · dual-energy X-ray absorptiometry | Biomarker | Gold-standard scan for body composition and bone density. ~10 minutes, trivial radiation. The number worth tracking isn't body fat percent — it's lean mass over time, especially during GLP-1 use. |
| DHA / EPA | omega-3 · fish oil · docosahexaenoic acid · eicosapentaenoic acid | Drug / molecule | Long-chain omega-3 fatty acids from fish and algae. EPA pulls inflammation down; DHA builds brain and retina. The 2018 VITAL trial cooled the early-cardiac hype; structural and mental-health signals remain real. |
| DMAE | dimethylaminoethanol | Drug / molecule | Old-school choline-adjacent nootropic. Some focus and mood data, mixed safety signal. Outclassed by alpha-GPC and citicoline for most modern stacks. |
| Double-blind | double-blinded | Study design | Neither participants nor researchers know who got drug vs. placebo until the data is locked. Blocks expectation bias on both sides. The minimum bar for serious clinical evidence. |
| Down-regulation | receptor desensitization | Concept | Receptors get tired. Chronic high-dose exposure to a signaling molecule makes cells reduce receptor density — why caffeine tolerance, opioid tolerance, and continuous-instead-of-pulsatile peptide dosing all blunt response. |
| Effect size | Cohen's d | Study design | How big the result actually is, separate from whether it's 'statistically significant.' A small effect across millions matters; a huge effect in 12 mice is hypothesis-generating, not actionable. |
| EFSA | European Food Safety Authority | Study design | EU's equivalent of the FDA for food, supplements, and food contact materials. Often stricter on health-claim language than FDA. Worth checking when a US supplement makes a claim its EU counterpart cannot. |
| Endocrine disruptor | EDC | Concept | Compounds that hijack hormone signaling — BPA, phthalates, atrazine, certain parabens. Dose and exposure timing matter; in-utero exposure dwarfs adult effects. Practical move: minimize, don't panic. |
| Eric Topol | Topol | Researcher | Cardiologist; Scripps Research. Sharp critic of pharma overreach and weak digital-health hype. Pro AI-in-medicine; pro long-COVID research. One of the more reliable medical commentators on social media. |
| Estradiol | E2 | Drug / molecule | Primary estrogen. Women: cycle and menopause regulator. Men: 20-30 pg/mL is healthy — not 'as low as possible.' Both crashing and ballooning estradiol cause symptoms; ratio with testosterone matters more than either number alone. |
| FAO/WHO | Food and Agriculture Organization · World Health Organization | Study design | Joint UN bodies that publish reference equations for energy needs, protein requirements, and activity multipliers used in every BMR/TDEE calculator. |
| Ferritin | — | Biomarker | Iron-storage protein measured in blood. Low ferritin signals iron deficiency before hemoglobin drops; high ferritin can mean overload, inflammation, or liver issue. Athletes and menstruating women need to track it. |
| First-pass metabolism | hepatic first pass | Pharmacology | Liver chews up a swallowed drug before it reaches the bloodstream. Why some compounds are useless orally and effective injected or sublingual — bypassing first-pass changes bioavailability by orders of magnitude. |
| GHK-Cu | copper peptide · copper tripeptide | Drug / molecule | Copper-binding tripeptide originally identified in human plasma. Strong in-vitro skin and wound-healing data; topical formulations are well-validated. Injectable use is off-label with thinner evidence. |
| GIP | glucose-dependent insulinotropic polypeptide | Drug / molecule | Gut incretin hormone. On its own it's metabolically neutral; combined with GLP-1 (as in tirzepatide) it amplifies weight loss and may protect lean mass. The 'plus' in dual agonists. |
| GLP-1 | GLP1 · glucagon-like peptide-1 | Drug / molecule | Gut hormone released after meals. Slows stomach emptying, blunts appetite, sharpens insulin response. Class includes semaglutide (Ozempic/Wegovy), liraglutide, and the dual GLP-1/GIP tirzepatide (Mounjaro/Zepbound). |
| Glycemic variability | glucose swings | Biomarker | How much your blood sugar swings during a day. A CGM metric — high variability is worse than the same average with smooth lines. Driven mainly by meal composition and sleep, not exotic supplements. |
| Half-life | t1/2 · halflife · elimination half-life | Pharmacology | Time for the body to clear half of a drug from plasma. After ~5 half-lives, the drug is effectively gone. Semaglutide ≈ 1 week (weekly dosing); BPC-157 ≈ 30 min (daily injections); caffeine ≈ 5 hours (why afternoon coffee wrecks sleep). |
| HbA1c | A1c · glycated hemoglobin | Biomarker | Average blood glucose over roughly three months, read off how sugary your red blood cells are. <5.7% normal, 5.7-6.4% prediabetic, ≥6.5% diabetic. Less granular than a CGM but cheaper and standardized. |
| HOMA-IR | Homeostatic Model Assessment · insulin resistance index | Biomarker | Insulin-resistance estimate from fasting glucose × fasting insulin ÷ 405. Under 1.0 is excellent, 1-2 OK, over 2.5 problematic. Cheap, useful, and underordered — most doctors only check glucose. |
| HPG axis | hypothalamic-pituitary-gonadal axis | Concept | Brain → pituitary → gonads feedback loop that controls sex hormones. Anabolic steroids, opioids, and chronic stress all suppress it. Recovery after suppression takes months, sometimes years. |
| HRV | heart rate variability | Biomarker | Beat-to-beat variation in your heartbeat. Higher generally = better autonomic balance and recovery. Best read as a personal trend, not compared between people. Tanks with poor sleep, alcohol, and overreaching. |
| hs-CRP | high-sensitivity C-reactive protein | Biomarker | Sensitive inflammation marker. <1 mg/L = low cardiac risk, >3 = elevated. Tracks chronic, low-grade inflammation that drives heart disease, metabolic disease, and depression. |
| Hyaluronic acid | HA | Drug / molecule | Big sugar-protein that holds water in skin, joints, and eyes. Injected forms work (filler, knee). Topical works for hydration. Oral supplementation is mostly digested before it can do anything. |
| IGF-1 | insulin-like growth factor 1 | Drug / molecule | Downstream messenger of growth hormone, produced mainly by the liver. The number GH is actually doing its work through. High IGF-1 grows tissue (including unwanted tissue) — why blanket GH for adults is contested. |
| Incretin | — | Concept | Class of gut hormones (GLP-1, GIP) released after eating that push the pancreas to release insulin and signal satiety. The whole modern weight-loss drug class is incretin biology. |
| Intermittent fasting | IF · time-restricted eating · TRE · 16:8 | Concept | Compressing your eating window — 16:8, 18:6, 24h fasts. Modest weight-loss tool; metabolic benefits are mostly the calorie deficit and better sleep. Recent RCTs are unimpressed when calories are matched. |
| IRB | Institutional Review Board | Study design | Ethics committee that approves and monitors human research. 'IRB-approved' is the minimum bar — not a quality signal on its own. |
| IU | international unit | Pharmacology | Activity-based dosing unit used when a compound's mass doesn't map cleanly to biological effect. Vitamin D, vitamin E, insulin, and growth hormone are all dosed in IU. |
| Kisspeptin | — | Drug / molecule | Hypothalamic peptide that gates the entire reproductive axis by triggering GnRH release. Investigational for hypogonadism; promising libido data in early trials. |
| L-theanine | theanine | Drug / molecule | Amino acid in green tea. Pairs with caffeine to smooth jitter and sharpen focus. ~200 mg works; higher doses don't scale benefit. One of the few stack ingredients with consistent EEG and behavioral data. |
| Lipid panel | cholesterol panel | Biomarker | Total cholesterol, LDL-C, HDL-C, and triglycerides — the basic blood-fat checkup. Useful but incomplete: ApoB and Lp(a) catch risk a standard panel misses. |
| Lp(a) | lipoprotein a · lipoprotein little a | Biomarker | Genetic LDL variant elevated in roughly 1 in 5 people. Independent cardiac risk factor; barely moves with diet or statins. Worth measuring once — the result informs how aggressive other risk control should be. |
| Mark Hyman | Hyman | Researcher | Functional medicine physician; prolific author. Bestseller-level reach. Mixes solid nutrition fundamentals with supplement-heavy protocols and a commercial product ecosystem to watch. |
| Meta-analysis | meta analysis | Study design | Statistical pooling of many trials into one combined estimate. Stronger than any single RCT — when the underlying trials are good. Garbage in, polished garbage out: a meta-analysis of weak studies is still weak. |
| Mitophagy | — | Concept | Targeted autophagy of mitochondria. Damaged mitochondria are pruned and replaced. Stimulated by exercise, Urolithin A, fasting. Probably one of the highest-leverage levers in healthspan biology. |
| MK-7 | menaquinone-7 · vitamin K2 MK-7 | Drug / molecule | Long-half-life form of vitamin K2. Directs calcium toward bone and away from arteries. ~180 µg/day is a common functional dose; pairs naturally with vitamin D3. |
| MOTS-c | — | Drug / molecule | Peptide encoded inside mitochondrial DNA — rare for a peptide. Animal data on metabolic flexibility and insulin sensitivity. Human use is investigational and supplied by gray-market peptide vendors. |
| Mounjaro | tirzepatide | Drug / molecule | Tirzepatide branded for type-2 diabetes by Eli Lilly. Dual GLP-1 / GIP agonist. Same molecule as Zepbound (dosed for weight loss). Outperforms semaglutide in head-to-head trials. |
| mTOR | mechanistic target of rapamycin · mammalian target of rapamycin | Concept | Master growth switch in every cell. Fed and trained → mTOR up → muscle and tissue build. Inhibited (rapamycin, fasting) → repair and longevity pathways win. The chronic-on-mTOR state is what most longevity work tries to escape. |
| NAD+ | nicotinamide adenine dinucleotide · NAD | Drug / molecule | Coenzyme central to energy production and DNA repair. Declines with age — whether boosting it back delivers human benefit is still actively contested. Precursors (NMN, NR) are the supplement form. |
| NMN / NR | nicotinamide mononucleotide · nicotinamide riboside | Drug / molecule | NAD+ precursors. Both raise NAD+ in blood; clinical outcomes in healthy adults remain modest. NMN faced US regulatory uncertainty in 2022 (FDA reclassification); NR has more human RCT data. |
| NNT | number needed to treat | Study design | How many people you need to treat for one to benefit. NNT of 50 for a heart-attack prevention drug = 49 people get medicated for nothing so 1 gets saved. The number doctors usually don't quote. |
| Off-label use | off label prescription | Pharmacology | Prescribing an FDA-approved drug for a use it isn't approved for. Common, legal for physicians, and how most of medicine actually works — but insurance coverage, dosing data, and safety surveillance are all thinner. |
| Omega-3 index | O3i | Biomarker | EPA + DHA as a percent of red-blood-cell fatty acids. Target ≥8%. The actionable version of 'are my omega-3s working' — much more useful than counting milligrams swallowed. |
| Ozempic | semaglutide | Drug / molecule | Semaglutide, branded for type-2 diabetes by Novo Nordisk. Weekly subcutaneous injection. Same molecule as Wegovy (which is dosed higher for weight loss). The drug that put GLP-1s on every front page. |
| p-value | p value · p < 0.05 | Study design | Probability of seeing your result if nothing real is happening. p < 0.05 became the convention; it was never a magic threshold. Effect size and pre-registration matter more than crossing 0.05. |
| Peter Attia | Attia | Researcher | Longevity physician, author of Outlive. Championed ApoB-first lipid thinking, VO2 max as mortality marker, and Zone 2 training in popular discourse. WR coverage tends to agree on lipids and exercise; we hedge on his rapamycin enthusiasm. |
| Pharmacodynamics | PD | Pharmacology | What a drug does TO the body — the receptor binding, the downstream signaling, the actual effect. PK gets the drug there; PD is what it does once it arrives. |
| Pharmacokinetics | PK | Pharmacology | What the body does TO a drug — absorption, distribution, metabolism, excretion. Pharmacokinetics decides peak levels, half-life, and dosing schedule. |
| Placebo | sham | Study design | Inert comparator used to separate drug effect from belief, ritual, and natural recovery. Placebo responses are real and frequently large — which is why uncontrolled biohacker testimonials look more impressive than they deserve to. |
| PPI | proton pump inhibitor · omeprazole · pantoprazole | Drug / molecule | Acid-suppression drugs (omeprazole, pantoprazole). Effective short-term; chronic use links to B12, magnesium, and possibly fracture risk. Most long-term PPI use is non-essential and rarely reviewed. |
| Rapamycin | sirolimus | Drug / molecule | Macrolide originally for transplant immunosuppression. mTOR inhibitor. Animal data on lifespan is the strongest of any small molecule; human use for longevity is widespread off-label and lightly evidenced. |
| RCT | randomized controlled trial | Study design | Subjects randomly assigned to treatment vs. control. The strongest single study design we have. Quality still varies wildly — blinding, sample size, and adherence matter at least as much as the RCT label. |
| Reverse T3 | rT3 | Biomarker | Inactive twin of T3 thyroid hormone. Elevated rT3 can signal stress, calorie restriction, or chronic illness — not 'broken thyroid.' Useful diagnostic context, not a standalone problem to treat. |
| Rhonda Patrick | Patrick | Researcher | Biochemist; FoundMyFitness host. Heavy emphasis on micronutrients (omega-3, magnesium, vitamin D), heat shock, and Mediterranean diet. Strong on reading the literature carefully; commercial sponsorship has grown. |
| Robert Lustig | Lustig | Researcher | Pediatric endocrinologist. Built the modern public case against added sugar and ultra-processed food (Fat Chance, Metabolical). Sometimes more polemical than the meta-analyses warrant — but directionally well-supported. |
| SC injection | subcutaneous · subQ · sub-q | Pharmacology | Injection into the fat layer under the skin. Standard route for insulin, GLP-1s, and most peptides. Slower absorption than IM, easier to self-administer, less bruising. |
| Semaglutide | — | Drug / molecule | Novo Nordisk's GLP-1 receptor agonist. Sold as Ozempic (diabetes) and Wegovy (weight loss). Also tablet form (Rybelsus) with much lower bioavailability. |
| SHBG | sex hormone-binding globulin | Biomarker | Protein that binds testosterone and estradiol in blood, controlling how much is biologically active. Insulin resistance drops SHBG; oral estrogen and thyroid hormone raise it. Why total testosterone alone misleads. |
| SIBO | small intestinal bacterial overgrowth | Concept | Bacteria growing where they shouldn't — the small intestine. Causes bloating, gas, malabsorption. Breath-test diagnosis is imperfect; treatment cycles (rifaximin) often need repeating. |
| Sirtuins | SIRT1 · SIRT3 | Drug / molecule | NAD+-dependent enzymes that adjust gene expression toward stress resistance and metabolic efficiency. Major character in the longevity story; the human translation of mouse sirtuin work has been slower than the marketing. |
| Statin | atorvastatin · rosuvastatin | Drug / molecule | HMG-CoA reductase inhibitors. Reduce LDL and ApoB; the single best-evidenced cardiac-prevention drug class we have. Side effects (muscle, glucose) are real but smaller in trials than internet discourse suggests. |
| TDEE | total daily energy expenditure | Concept | Total calories you burn in a day: BMR + activity + thermic effect of food. Calculator estimates land ±15% — adjust against the scale over weeks, not against the spreadsheet. |
| Therapeutic window | therapeutic index | Pharmacology | Gap between the dose that works and the dose that hurts. Wide window (acetaminophen, GLP-1s): forgiving. Narrow window (lithium, warfarin): every milligram matters. |
| Tirzepatide | — | Drug / molecule | Eli Lilly's dual GLP-1 / GIP receptor agonist. Weekly subcutaneous. In trials, average weight loss exceeds semaglutide by several percentage points. The current frontier of approved metabolic drugs. |
| Titration | dose escalation | Pharmacology | Climbing toward the right dose in steps rather than starting at the target. Standard for GLP-1s, SSRIs, TRT. Skipping titration is the most common reason someone 'doesn't tolerate' a drug they would have tolerated fine. |
| TRT | testosterone replacement therapy | Drug / molecule | Exogenous testosterone for diagnosed hypogonadism (or, very often, for symptoms below the lab cutoff). 2026 FDA expansion to include libido changed the prescribing landscape. Demands monitoring of estradiol, hematocrit, PSA. |
| TSH | thyroid-stimulating hormone | Biomarker | Pituitary signal telling the thyroid to work harder. The standard front-line thyroid test. By itself it can lag months behind a real problem — pair with free T4 and free T3 when symptoms don't match. |
| Urolithin A | UA | Drug / molecule | Metabolite your gut makes (or doesn't) from pomegranate ellagitannins. Activates mitophagy. About 40% of adults don't produce it well — direct supplementation bypasses that. Best human data in older adults. |
| UV index | UVI | Biomarker | Forecast of sunburn intensity, 0-11+. Above 3, unprotected pale skin burns. The number that should drive sunscreen decisions — not 'is it summer.' |
| Valter Longo | Longo | Researcher | USC biologist behind the Fasting-Mimicking Diet (Prolon). Substantial work on fasting, IGF-1, and chemo protection. Has more peer-reviewed depth than most popular longevity figures. |
| VAT | visceral adipose tissue | Biomarker | Fat packed around organs (not under skin). Metabolically active and inflammatory — drives insulin resistance and cardiac risk far more than subcutaneous fat. DEXA and MRI quantify it directly. |
| Vitamin D | 25-OH-D · 25-hydroxyvitamin D · vitamin D3 · cholecalciferol | Drug / molecule | Fat-soluble hormone-vitamin. Measure as 25-hydroxyvitamin D; target 40-60 ng/mL for most adults. Pair supplementation with K2 if dosing >2000 IU/day. The supplement aisle's headline molecule, deserved. |
| VO2 max | VO2max · maximal oxygen uptake | Biomarker | Maximum oxygen your body can use during exercise. One of the strongest predictors of all-cause mortality. Trainable at any age — Norwegian 4x4 intervals are the most efficient protocol. |
| Wash-out | washout period | Pharmacology | Wait time after stopping a drug before plasma falls to negligible. Roughly 5 half-lives. Matters for stacking, drug interactions, and trial design — and explains why semaglutide takes ~5 weeks to fully leave. |
| Wegovy | semaglutide for weight loss | Drug / molecule | Higher-dose semaglutide branded for obesity (2.4 mg weekly). Same molecule as Ozempic. The drug that drove the GLP-1 obesity-pricing fight. |
| Zepbound | tirzepatide for weight loss | Drug / molecule | Tirzepatide branded for obesity. Same molecule as Mounjaro. The other dominant prescription in the modern weight-loss landscape. |
| Zone 2 | aerobic base · MAF | Concept | Steady aerobic effort where you can still talk in sentences — roughly 60-70% of max heart rate. The intensity that builds mitochondria and metabolic flexibility. 3-4 hours a week is the working target Attia popularized. |
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.