Glossary

A section of federal law that lets a licensed pharmacy compound a medication for an individual patient's prescription, outside the FDA approval process.

An FDA-registered compounding facility that can make larger batches under CGMP standards and FDA inspection — a step above 503A, but still not an FDA-approved manufactured drug.

A blood test measuring average blood sugar over the past 2-3 months, used to diagnose and monitor diabetes.

A larger-than-expected drop in the calories your body burns during weight loss, beyond what the loss of body mass alone would predict.

A general pharmacology term for any substance that activates a receptor to produce a biological response.

A reduced ability to feel pleasure, including from food — sometimes reported on GLP-1 medications alongside appetite and reward changes.

The raw drug substance in a medication that produces its effect — for example, semaglutide itself, before it is formulated into a pen or vial.

The number of complete (apnea) and partial (hypopnea) breathing interruptions per hour of sleep, measured in a sleep study; it grades obstructive sleep apnea as mild (5–14), moderate (15–29), or severe (30+).

A formal request asking your insurer to reconsider a denied claim or prior authorization.

A reduction in the drive or desire to eat, distinct from the fullness felt during or after a meal.

Weight-loss surgery (such as gastric bypass or sleeve gastrectomy) that alters the digestive system, often compared to GLP-1 medications as a treatment option.

Bioelectrical impedance analysis — a body composition measurement method that estimates fat and lean mass by sending a small electrical current through the body.

An eating disorder involving recurrent episodes of eating large amounts of food with a sense of loss of control, and distress afterward — without compensatory purging.

A biologic medication highly similar to an already-approved reference drug, often available at lower cost once patents expire.

Body mass index: a weight-to-height ratio commonly used as a screening threshold for obesity and GLP-1 eligibility.

A mental health condition involving persistent, distressing preoccupation with perceived flaws in appearance — a consideration for anyone undergoing rapid body change.

Losing fat while keeping or building muscle, so the body's fat-to-muscle ratio improves even if total weight changes little.

The FDA's strongest prescription-drug warning, set in a black-bordered box at the top of the label to flag a serious or life-threatening risk.

A large randomized trial built specifically to measure a drug's effect on heart attacks, strokes, and cardiovascular death, as opposed to surrogate markers like blood sugar or weight.

A document reporting the lab test results for a specific batch of a drug ingredient or product, such as identity, purity, and contaminants.

A structured, time-limited form of talk therapy (CBT) that works on the links between thoughts, feelings, and behaviors, with strong evidence for anxiety, depression, insomnia, and binge eating.

The percentage of a drug's cost you're responsible for paying, after any deductible is met.

A health condition that exists alongside a primary condition, for example type 2 diabetes, high blood pressure, or sleep apnea occurring with obesity.

A version of semaglutide made by a compounding pharmacy rather than the original manufacturer — not FDA-approved as a standalone product.

A pharmacy licensed to prepare customized medications, including compounded versions of GLP-1 drugs, outside of standard manufacturer production.

A fixed dollar amount you pay out-of-pocket for a prescription or visit, set by your insurance plan.

The main glucocorticoid hormone, released by the adrenal glands on a daily rhythm to raise blood sugar, sharpen alertness, and manage stress; chronically high levels break down muscle and, in true excess, drive central fat.

Continuous positive airway pressure: a bedside machine that blows gently pressurized air through a mask to hold the airway open during sleep, the standard first-line treatment for obstructive sleep apnea.

A compound stored in muscle that helps power short, intense effort; one of the most-studied supplements for supporting strength and muscle.

A condition of persistently excessive cortisol, caused by a hormone-producing tumor or long-term glucocorticoid medication, producing central weight gain, a rounded face, easy bruising, and muscle weakness — distinct from ordinary stress.

The amount you must pay out-of-pocket before your insurance starts covering costs.

A range of irregular or harmful eating behaviors that may not meet the full criteria for a diagnosed eating disorder but still deserve attention and care.

Dipeptidyl peptidase-4, the enzyme that rapidly breaks down the body's own GLP-1 within minutes.

A medication that activates two hormone receptors at once — for example, tirzepatide, which targets both GLP-1 and GIP receptors.

A specialized X-ray scan that measures body composition, including fat mass, lean mass, and bone density.

How well a medication performs in everyday, real-world use, as opposed to the controlled conditions of a clinical trial.

How well a medication performs under ideal, controlled conditions — typically measured in clinical trials.

A U.S.-based pharmaceutical company that makes tirzepatide (Mounjaro, Zepbound) and orforglipron (Foundayo), among other medications.

A toxin from the outer wall of certain bacteria that can contaminate poorly made injectable products and trigger fever, chills, and serious reactions.

The FDA's decision to temporarily not take action against conduct that technically violates the rules, such as the grace periods it gave compounders after the GLP-1 shortages ended.

The federal law governing most employer-sponsored health plans, which largely exempts self-funded plans from state insurance mandates and sets the rules for claims and appeals.

An independent, outside review of an insurer's denial after internal appeals are exhausted, with a decision the plan must follow.

The FDA's database of voluntary side-effect reports from patients, clinicians, and manufacturers, used to detect safety signals after a drug is on the market. In March 2026 it became part of the FDA Adverse Event Monitoring System (AEMS).

A patient who experiences significant appetite suppression and weight loss quickly, often at lower doses, after starting a GLP-1 medication.

Everything in the body that isn't fat — muscle, organs, bone, and water — measured as total body weight minus all fat mass.

A colloquial term for persistent, intrusive thoughts about food — commonly reported to diminish significantly on GLP-1 medications.

The list of medications your plan covers, organized into cost tiers.

A request asking your plan to cover a drug that isn't on its formulary, or to cover it at a lower tier, based on medical need.

Eli Lilly's brand name for oral orforglipron, a GLP-1 medication for adults with obesity or excess weight plus weight-related medical problems.

Reduced testosterone in men that results from a reversible cause such as obesity, type 2 diabetes, or sleep apnea rather than damage to the hormonal axis; it typically improves with weight loss and is not an indication for testosterone therapy.

The rate at which the stomach passes its contents into the small intestine, which GLP-1 medications slow down.

A diagnosis of abnormally delayed stomach emptying with persistent symptoms. GLP-1 medications cause mild, temporary slowing in many people, which is not the same thing, but the Wegovy label says it is not recommended in severe gastroparesis.

A mental health condition marked by persistent, excessive, hard-to-control worry about many things over months, often with restlessness, tension, and poor sleep.

Glucose-dependent insulinotropic polypeptide — a second gut hormone, alongside GLP-1, that some newer medications (like tirzepatide) target together.

A gut hormone (glucagon-like peptide-1) that stimulates insulin release, slows digestion, and reduces appetite; the target of drugs like semaglutide and liraglutide.

A colloquial term for facial volume loss and skin laxity that can accompany rapid, significant weight loss on GLP-1 medications.

A comparison between single-hormone GLP-1 drugs (e.g. semaglutide) and dual-hormone GLP-1/GIP drugs (e.g. tirzepatide).

A hormone that raises blood sugar by triggering the liver to release stored glucose — the functional counterpart to insulin, and an emerging target in newer GLP-1-class medications.

A regulatory standard ensuring medications are consistently produced and controlled to quality standards — a key marker of legitimacy for compounded or manufactured drugs.

The unauthorized sale of medications outside official manufacturer and pharmacy supply chains — not necessarily counterfeit, but unregulated, risky, and for GLP-1s sold without a prescription, against U.S. drug law.

The time it takes for half of a drug dose to be cleared from the body — determines how often a medication needs to be taken.

A statistic from clinical trials that compares how often an event happens over time in one group versus another; below 1 means a lower rate in the treated group.

Eating driven by pleasure, reward, or cravings rather than physical hunger.

Treatment that replaces a hormone the body no longer produces in adequate amounts — most commonly estrogen (usually with a progestogen) for menopausal women, or testosterone for men with hypogonadism. It is not a weight-loss treatment and is separate from GLP-1 medications.

Blood sugar that drops below the normal range (typically under 70 mg/dL), causing shakiness, sweating, confusion, or worse.

A condition of low sex-hormone production. In men it means low testosterone with symptoms; importantly, the low testosterone that often accompanies obesity is frequently a reversible state ('pseudo-hypogonadism') rather than true, pathologic hypogonadism.

Abnormally low blood sodium, which can happen when fluid losses are replaced with plain water alone or food intake is very low.

A popular brand of bioelectrical impedance device used to measure body composition, often found in gyms and clinics.

A class of gut hormones, including GLP-1 and GIP, that trigger insulin release in response to food.

Body weight from everything other than fat: mostly muscle, plus organs and water, and in the broad sense bone. On a DXA report, lean mass usually leaves bone out.

The minimum difference between two scans on the same machine that can be considered a true change rather than measurement error, usually reported as a percentage or in grams.

A prescriber's written statement explaining why a specific medication is medically required for a patient, used to support prior authorization and appeals.

An essential amino acid that is the main dietary trigger of muscle protein synthesis.

Luteinizing hormone and follicle-stimulating hormone: two pituitary hormones that signal the testes and ovaries to make sex hormones and sperm or eggs.

Eli Lilly's direct-to-patient platform offering telehealth access, home delivery, and savings programs for its medications, including Mounjaro and Zepbound.

A rubbery lump of thickened fatty tissue under the skin caused by repeated injections in the same spot.

A first-generation GLP-1 receptor agonist taken as a daily injection, sold as Victoza for type 2 diabetes and Saxenda for weight management, and now also as a US generic.

The smallest dose of a medication that produces the intended benefit with tolerable side effects. It is a standard prescribing principle.

A composite trial endpoint bundling cardiovascular death, non-fatal heart attack, and non-fatal stroke into a single outcome.

The stable, ongoing dose taken once titration is complete, intended to sustain treatment effects long-term.

The insurer's determination that a treatment is required to diagnose or treat a condition, often required for coverage approval.

A rare thyroid cancer arising from the thyroid's C cells; a personal or family history of it is a contraindication to GLP-1 medications.

An inherited syndrome that raises the risk of medullary thyroid carcinoma and is a contraindication to most GLP-1 medications.

Estrogen, usually combined with a progestogen (when the uterus is present), used to relieve menopausal symptoms such as hot flashes and to protect bone. Often just called 'HRT.' It is associated with less visceral fat but is not a weight-loss treatment.

Eli Lilly's brand name for injectable tirzepatide, FDA-approved for type 2 diabetes (adults and children 10+) and for cardiovascular risk reduction in high-risk adults with type 2 diabetes.

The biological process of building new muscle protein, stimulated by resistance exercise and dietary protein intake.

The energy burned by everyday movement that isn't planned exercise — walking, standing, chores, fidgeting.

A Danish pharmaceutical company that makes semaglutide (Ozempic, Wegovy) and liraglutide (Victoza, Saxenda), among other medications.

Novo Nordisk's patient support platform offering savings programs, insurance guidance, and prescription access for its medications, including Ozempic and Wegovy.

A U.S. nonprofit patient advocacy organization focused on obesity education, awareness, and access to treatment.

A sleep disorder in which the airway repeatedly collapses during sleep, causing brief pauses in breathing; it is closely linked to obesity.

Prescribing a medication for a condition or in a manner not officially FDA-approved.

The annual window when you can enroll in or change your health plan, and the time to compare GLP-1 coverage across the plans available to you.

Semaglutide taken as a once-daily pill instead of a weekly injection: Rybelsus and its reformulation, Ozempic tablets, for type 2 diabetes, and the Wegovy pill for weight management.

The most common form of arthritis, in which the cartilage and other tissues of a joint gradually break down, causing pain and stiffness; excess weight is a major risk factor, especially for the knees.

The most you'll have to pay for covered services in a plan year before insurance covers 100% of costs.

Novo Nordisk's brand name for semaglutide for type 2 diabetes, sold as a weekly injection and, since May 2026 in the US, as daily Ozempic tablets.

The panel of physicians, pharmacists, and other clinicians that reviews the clinical evidence behind a plan's formulary: which drugs are acceptable, which are interchangeable, and what restrictions apply.

Inflammation of the pancreas — a rare but serious potential side effect of GLP-1 medications requiring immediate medical attention.

A manufacturer- or nonprofit-run program that provides free or discounted medication to eligible patients who can't afford it.

A third-party company that manages prescription drug benefits on behalf of insurers or employers, including which drugs are covered.

A short chain of amino acids: the molecular structure of the natural hormones GLP-1 medications mimic, and of most of the medications themselves.

The science and practice of detecting, assessing, and preventing adverse effects of medications once they are in real-world use, after clinical trials end.

A common hormonal condition in women involving irregular or absent periods, higher androgen levels, and frequently insulin resistance and weight gain; GLP-1 medications are increasingly used for weight management in PCOS.

An overnight, in-lab sleep study that records brain activity, breathing, blood oxygen, heart rhythm, and movement to diagnose sleep disorders — the gold-standard test for obstructive sleep apnea.

Approval your insurer requires before it will cover a medication.

A hormone — natural progesterone or a synthetic progestin — given alongside estrogen in menopausal hormone therapy to protect the lining of the uterus.

A drug that binds to and activates a specific receptor, mimicking the effect of the body's natural hormone.

Exercise that loads your muscles against resistance and is made gradually harder over time (progressive overload) to keep or build muscle and strength.

The calories your body burns at complete rest just to keep basic functions running; usually the largest share of daily energy expenditure.

An investigational triple agonist medication (GLP-1, GIP, and glucagon) developed by Eli Lilly, in phase 3 trials and not yet FDA-approved as of September 2026.

The age- or illness-related loss of muscle mass and strength — a risk to monitor for during rapid weight loss.

The feeling of fullness that builds during a meal and signals you to stop eating.

The sense of fullness that persists between meals, delaying the return of hunger.

A manufacturer-provided coupon that reduces out-of-pocket cost for insured patients, typically not usable with government insurance.

A brand of liraglutide, a daily-injection GLP-1 receptor agonist approved for chronic weight management and made by Novo Nordisk.

A medical-grade body composition measurement device made by Seca, using bioelectrical impedance to estimate fat and lean mass.

An employer health plan where the employer pays claims from its own funds instead of buying insurance, giving it direct control over what's covered.

A GLP-1 receptor agonist medication made by Novo Nordisk, sold under the brand names Ozempic (type 2 diabetes) and Wegovy (weight management), each as an injection or a pill.

Versions of semaglutide such as semaglutide sodium and semaglutide acetate, which the FDA says are different active ingredients from the semaglutide base used in approved drugs, with no known lawful basis for compounding.

A puncture-resistant container for safely collecting used needles, pen needles, and syringes until they can be disposed of according to local rules.

A protein that binds and transports sex hormones (including testosterone) in the blood. Obesity lowers SHBG, which reduces measured total testosterone and is a major reason obesity can look like low testosterone on a lab test.

A patient who experiences minimal appetite suppression or weight loss at typical doses, often requiring longer titration or higher doses to see results.

A rule requiring you to try lower-cost options before a plan covers another.

A class of oral type 2 diabetes medications (e.g. glipizide, glimepiride, glyburide) that stimulate the pancreas to release insulin regardless of blood sugar level.

The total number of calories your body burns in a day, combining resting metabolism, digestion, everyday movement, and exercise.

The broad use of digital communication technology to deliver healthcare services and information remotely.

The delivery of clinical medical services remotely, such as virtual doctor visits and prescribing — a subset of telehealth.

A temporary form of diffuse hair shedding that begins two to three months after a physical stressor — including rapid weight loss — pushes many hair follicles into their resting phase at once.

Replacing testosterone in men who have hypogonadism (clinically low testosterone plus symptoms), delivered as a gel, injection, patch, or pellet. It is for a specific diagnosis, not a default treatment for the reversible low testosterone that often accompanies obesity.

The energy your body spends digesting, absorbing, and processing food, typically about 10% of daily calorie burn and highest for protein.

A once-weekly dual GIP and GLP-1 receptor agonist made by Eli Lilly, marketed as Mounjaro for type 2 diabetes and Zepbound for weight management and obstructive sleep apnea.

The gradual, step-by-step increase of a medication dose over time, used to reduce side effects.

A syringe marked in "units" where 100 units equal 1 mL — designed for U-100 insulin but commonly used to draw compounded GLP-1 doses from vials.

The United States Pharmacopeia standard for sterile compounding that traditional 503A pharmacies must follow when preparing injectable medications.

A brand of liraglutide, a daily-injection GLP-1 receptor agonist approved for type 2 diabetes and made by Novo Nordisk.

Fat stored deep in the abdomen around the internal organs, which is more strongly tied to metabolic and cardiovascular risk than fat under the skin.

Novo Nordisk's brand name for semaglutide (weekly injection or, since December 2025, a daily pill), FDA-approved for chronic weight management and heart-risk reduction, and as an injection for MASH liver disease.

A period during treatment when weight loss slows or stalls despite continued medication use.

The return of lost weight, commonly seen after stopping a GLP-1 medication.

Negative attitudes, stereotypes, and discrimination directed at people because of their body weight, including within healthcare.

Eli Lilly's brand name for injectable tirzepatide, FDA-approved for chronic weight management and for moderate-to-severe obstructive sleep apnea in adults with obesity.

Brand name for ondansetron, an anti-nausea medication sometimes prescribed alongside GLP-1 medications to manage nausea side effects.