Glossary

Absorption enhancer (SNAC)

An ingredient in oral semaglutide tablets that helps a small fraction of the drug pass through the stomach wall. It is why the Wegovy pill must be taken on an empty stomach with only a little water. Read more →

BMI (body mass index)

Weight in kilograms divided by height in meters squared. In adults, 25 to under 30 is classed as overweight and 30 or more as obesity. Weight-management GLP-1 labels use BMI 30, or 27 with a weight-related condition. Read more →

Boxed warning

The FDA's strongest label warning, shown in a box at the top of the prescribing information. GLP-1 medicines carry one about thyroid C-cell tumors. Read more →

Calorie deficit

Taking in less energy from food and drink than your body uses over time. A sustained deficit leads to weight loss. Read more →

Cholecystitis

Inflammation of the gallbladder, usually caused by gallstones. GLP-1 labels list gallbladder problems as a warning. Read more →

Chronic weight management

The FDA term for long-term treatment of obesity, or overweight with a weight-related condition, used alongside a reduced-calorie diet and more physical activity. Read more →

Compounded drug

A medicine mixed by a pharmacy rather than made as an FDA-approved product. The FDA says compounded GLP-1s are not reviewed for safety, effectiveness or quality and should only be used when an approved drug cannot meet a patient's needs. Read more →

Contraindication

A condition or situation in which a medicine should not be used. For GLP-1s, a personal or family history of medullary thyroid carcinoma or MEN 2 is one. Read more →

Dose escalation (titration)

Starting a medicine at a low dose and raising it step by step, as the labels describe, to reduce digestive side effects. Your prescriber sets the schedule. Read more →

Dual agonist (GIP/GLP-1)

A medicine that activates two hormone receptors. Tirzepatide (Zepbound, Mounjaro) activates both GIP and GLP-1 receptors. Read more →

Gastric emptying

How quickly food leaves the stomach. GLP-1 medicines slow it, which adds to fullness and is linked to nausea. Read more →

GIP

Glucose-dependent insulinotropic polypeptide, a gut hormone released after eating. Tirzepatide targets its receptor as well as the GLP-1 receptor. Read more →

GLP-1

Glucagon-like peptide-1, a hormone your gut releases after you eat. It helps release insulin when blood sugar is high, slows stomach emptying and acts on appetite centers in the brain. Read more →

GLP-1 receptor agonist

A medicine that activates the GLP-1 receptor, copying the hormone's effects for much longer than the natural hormone lasts. Semaglutide, liraglutide and orforglipron are examples. Read more →

Lean mass (fat-free mass)

Everything in the body that is not fat, including muscle, organs, bone and water. Part of the weight lost on GLP-1s is lean mass. Read more →

MASH

Metabolic dysfunction-associated steatohepatitis, a serious form of fatty liver disease. Wegovy is FDA-approved for adults with MASH and moderate to advanced liver scarring. Read more →

Medullary thyroid carcinoma (MTC)

A rare type of thyroid cancer. People with a personal or family history of it should not take GLP-1 medicines. Read more →

MEN 2

Multiple endocrine neoplasia syndrome type 2, an inherited condition that raises the risk of medullary thyroid cancer. It is a contraindication for GLP-1 medicines. Read more →

Off-label use

Prescribing a medicine for a use the FDA has not approved, such as using Ozempic, a diabetes product, only for weight loss. Read more →

Pancreatitis

Inflammation of the pancreas. It is a labeled risk of GLP-1 medicines; severe, persistent belly pain needs urgent medical care. Read more →

Placebo

An inactive look-alike treatment used in trials so the drug's real effect can be measured. Trial results are usually reported as drug versus placebo. Read more →

Plateau

A period when weight stops going down even though you keep the same habits, usually because the energy gap that drove the loss has closed. Read more →

Prescribing information (label)

The FDA-approved document for a medicine that lists its approved uses, dosing, warnings, side effects and trial results. Read more →

Prior authorization

An insurer's requirement to approve a medicine before it will pay, often with BMI or diagnosis criteria for GLP-1s. Read more →

Resistance (strength) training

Exercise that works muscles against a load, such as weights, bands or body weight. It is the best-supported way to limit muscle loss during weight loss. Read more →

Self-pay (cash) price

What you pay for a medicine without insurance. Manufacturers list self-pay prices for some GLP-1s through their own pharmacy programs. Read more →

STEP trials

The clinical trial program for semaglutide in weight management. STEP 1 found an average 14.9% weight loss at 68 weeks on 2.4 mg weekly versus 2.4% on placebo. Read more →

SURMOUNT trials

The clinical trial program for tirzepatide in weight management. In SURMOUNT-1, average weight loss at 72 weeks was 15.0% to 20.9% depending on dose, versus 3.1% on placebo. Read more →

Telehealth

Health care delivered remotely by video, phone or secure messaging. A licensed clinician can evaluate you and, if appropriate, prescribe a GLP-1. Read more →

Weight cycling

Repeatedly losing and regaining weight. It is linked to a higher risk of gallstones. Read more →

Looking for a specific medicine? See GLP-1 medications A–Z. New to all of this? Start here.