GLP-1 medicines change how full you feel, and that is most of how they work. This page explains the mechanism in plain terms, what a prescriber watches, and what Loopa records while you are on one.
Loopa does not prescribe, dispense or recommend any medication. Questions about your medication belong with your prescriber.
What GLP-1 means
GLP-1 is a hormone your gut releases when you eat. It tells your pancreas to release insulin, slows how fast the stomach empties, and acts on the parts of the brain that decide you have had enough. A GLP-1 medicine is a longer-lasting copy of that signal.
The practical result is that meals feel like enough sooner, and stay feeling like enough for longer. Most of the weight change follows from eating less, rather than from anything the medicine does to how you burn energy.
Some of these medicines act on GLP-1 alone. Tirzepatide acts on GLP-1 and on a second gut hormone, GIP, at the same time.
Who prescribes them, and for what
These are prescription medicines. In the United States they are approved for type 2 diabetes, for long-term weight management in adults meeting specified criteria, and for some cardiovascular indications, with the exact wording differing by product (FDA prescribing information, via openFDA: open.fda.gov drug labeling).
The World Health Organization issued its first global guideline on GLP-1 therapies for obesity in adults in 2025 (who.int), and the American College of Cardiology published consensus guidance on medical weight management the same year (Gilbert et al., JACC, 2025 · doi:10.1016/j.jacc.2025.05.024).
What to expect
Appetite changes first. Most people notice the difference in how much food it takes to feel full before they notice anything on the scale.
Gastrointestinal effects are the common ones. Nausea, vomiting, diarrhea and constipation appear in the adverse-reaction sections of the product labels as the most frequently reported effects (WEGOVY prescribing information, section 6.1). They are usually most noticeable after a change and tend to settle.
Progress is not linear. Weight moves in steps and pauses. See Understanding your trends.
Stopping matters. In a randomized withdrawal trial, participants who stopped regained a substantial part of the weight they had lost and cardiometabolic improvements moved back toward baseline (Wilding JPH et al., Diabetes, Obesity and Metabolism, 2022 · doi:10.1111/dom.14725). That is a fact about the medicine, not about the person taking it, and it is worth knowing before you start rather than after you stop.
What a prescriber typically monitors
Weight and how it is trending. How you are tolerating it. Whether you are eating and drinking enough. Blood work relevant to your own history. Anything on the label specific to your situation.
Loopa does not decide any of that and does not suggest a change to any of it.
Two things worth knowing before a procedure
If you have surgery or an endoscopy planned, tell the team you are on a GLP-1. Multisociety guidance published in 2024 covers shared decision-making about these medicines before a procedure and the factors that raise risk (Kindel TL et al., SOARD, 2024 · doi:10.1016/j.soard.2024.08.033). See GLP-1 medications and anesthesia.
How Loopa helps
Loopa records what you report and shows it back to you. It never tells you what to take.
- Log a dose. Health › Protocols, then your GLP-1 protocol. Loopa records the compound, the time and the site you tapped.
- Track how you feel. The daily check-in records energy, appetite, food noise and any symptoms, so a pattern is visible rather than remembered.
- See your own pattern. After three complete cycles Loopa can show which days after a dose your own logs say are your strongest and roughest. It describes what you recorded and interprets nothing.
- Prepare for an appointment. Health › Protocols › Summary for your appointment builds a file over a window you choose.
Related
- Semaglutide, tirzepatide and liraglutide: what is different
- Titration, and why doses change over time
- Protein first on a GLP-1, and why Loopa sets your targets that way
- Coming off a GLP-1
- Medication protocols
Where this comes from
Everything on this page is drawn from published clinical guidelines, regulatory labeling and peer-reviewed research, cited above. The full list, with a link to every original, is at loopahealth.app/sources. Loopa does not give medical advice. It does not decide whether a medicine is right for you, does not recommend one over another, and never sets a dose. Your prescriber does all three, and where they give you an instruction, theirs is the one to follow.
