Glossary
Plain-language definitions for the peptide and GLP-1 terms you'll run into while setting up and tracking a protocol. Educational reference only — not medical advice.
Basics
- Peptide
- A short chain of amino acids — smaller than a protein — that can act as a signaling molecule in the body.
- Amino acid
- The building blocks of peptides and proteins.
Compounds
- GLP-1
- Glucagon-like peptide-1, a hormone that regulates blood sugar and appetite; GLP-1 receptor agonists mimic it.
- Semaglutide
- A long-acting GLP-1 receptor agonist with a roughly one-week half-life, dosed weekly.
- Tirzepatide
- A dual GIP/GLP-1 receptor agonist, also long-acting and dosed weekly.
- Retatrutide
- An investigational triple agonist targeting GLP-1, GIP, and glucagon receptors.
- BPC-157
- A research peptide studied in the context of tissue and gut healing.
- TB-500
- A synthetic version of thymosin beta-4, studied for recovery and tissue repair.
- Ipamorelin
- A growth-hormone secretagogue peptide, often paired with CJC-1295.
- CJC-1295
- A growth-hormone-releasing hormone analog, commonly stacked with ipamorelin.
Dosing & Reconstitution
- Reconstitution
- Mixing a freeze-dried (lyophilized) compound with a liquid to make an injectable solution.
- Lyophilized
- Freeze-dried into a stable powder for storage; reconstituted with liquid before use.
- Bacteriostatic water
- Sterile water containing a small amount of benzyl alcohol that inhibits bacterial growth.
- Sterile water
- Purified water with no preservative — no antibacterial protection for multi-use vials.
- Diluent
- The liquid used to dissolve a lyophilized compound during reconstitution.
- Concentration
- How much compound is dissolved per unit of liquid, e.g. milligrams per milliliter (mg/mL).
- Units (insulin syringe)
- The graduation marks on an insulin syringe; 100 units equals 1 mL on a U-100 syringe.
- U-100
- An insulin syringe standard where 100 units equal 1 mL.
- U-40
- A less common insulin syringe standard where 40 units equal 1 mL.
- Syringe
- The instrument used to measure and administer an injectable solution.
- Subcutaneous (SubQ)
- Into the fatty layer just under the skin — a common route for peptide and GLP-1 injections.
- Intramuscular (IM)
- Into a muscle — a deeper injection route than subcutaneous.
- Titration
- Gradually adjusting a dose over time, often starting low and increasing.
- Cycle
- A defined period of using a compound, sometimes followed by a break ("off" time).
- Stack
- Using two or more compounds together as part of one protocol.
- Benzyl alcohol
- The preservative in bacteriostatic water that inhibits bacterial growth.
- Dead space
- The small volume of liquid left in a syringe or needle hub after injecting.
- Gauge
- A measure of needle thickness — higher gauge means a thinner needle.
Pharmacology
- GIP
- Glucose-dependent insulinotropic polypeptide, an incretin hormone that works alongside GLP-1.
- Incretin
- A group of gut hormones (including GLP-1 and GIP) released after eating that stimulate insulin.
- Secretagogue
- A substance that causes another substance — such as a hormone — to be secreted.
- Half-life
- The time it takes for the amount of a compound in the body to fall by half.
- Pharmacokinetics (PK)
- How a compound is absorbed, distributed, metabolized, and eliminated over time.
- Tmax
- The time after a dose at which the compound reaches its peak concentration.
- Cmax
- The peak concentration a compound reaches in the body after a dose.
- Steady state
- When regular dosing balances elimination, so average levels stay roughly constant.
Tracking
- Injection site
- The location on the body where an injection is given, such as the abdomen or thigh.
- Site rotation
- Cycling injections across different body locations rather than repeatedly using one spot.
- Medication level
- An estimate of how much of a compound is in your body at a given time, modeled from PK data.
- Protocol
- The overall plan for what compounds you take, how much, how often, and for how long.
- Reminder
- A scheduled notification prompting you to take or log a dose.
- Adherence
- How consistently you follow your intended dosing schedule.
- Depletion
- How quickly a reconstituted vial is being used up, and when it will run out.
- Inventory
- The record of what vials and compounds you currently have on hand.
- Side effect
- An unintended physical response you may notice and log alongside your protocol.
- Nausea
- A commonly reported GLP-1 side effect, especially during dose increases.
- Macros
- Macronutrients — protein, carbohydrates, and fat — often tracked alongside a protocol.
- Protein
- A macronutrient many prioritize on GLP-1 protocols to help preserve lean mass.
- Nutrition tracking
- Logging what you eat — calories and macros — alongside your protocol data.
- Bloodwork
- Lab test results — such as lipids or hormones — you can record and trend over time.
- Progress photo
- A dated photo kept to track visual body changes over the course of a protocol.