Guide 01 · GLP 101
What GLP Medications Are
You have heard the word Ozempic. This guide explains what is actually behind it, from zero, in about five minutes.
Start here
Ozempic is a brand name. The medication is Semaglutide.
Every famous weight-loss pen you have heard of is a brand name wrapped around one of three underlying medications. Ozempic and Wegovy are both Semaglutide. Mounjaro and Zepbound are both Tirzepatide. Retatrutide is new enough that it does not have a brand name yet; it is still known by the medication name itself.
All three belong to one family, usually called GLP medications. They are peptides, small chains of amino acids that copy hormones your own gut already makes. Injected once a week, they turn the volume down on appetite. People on them describe the same thing in different words: the food noise goes quiet.
The three medications are best understood as three generations of the same idea, each one targeting more of your gut hormones than the last.
The mechanism, plainly
Three hormones, three letters
GLP-1
Glucagon-like peptide-1
The original target, and the one in Ozempic. GLP-1 is a hormone your gut releases after you eat. It tells your brain you are full, slows how fast your stomach empties, and helps steady blood sugar. Mimic it with a medication and the effect is a quieter appetite: smaller portions feel like enough, and the constant background chatter about food fades.
GIP
Glucose-dependent insulinotropic polypeptide
A second gut hormone that works alongside GLP-1. Adding GIP activity appears to improve how the body handles sugar and fat and, in trials, added more weight loss than GLP-1 alone while helping with tolerability. This is the addition that defines the second generation.
Glucagon
Glucagon
The third pathway. Where GLP-1 and GIP mostly reduce what comes in, glucagon activity nudges up what goes out, increasing energy expenditure. Targeting all three at once is the idea behind the third generation, and it produced the largest average trial result so far.
The evidence
Three generations, three trials
Generation 1 · GLP-1
Semaglutide
The one in Ozempic and Wegovy
~15%avg. body weight lost in STEP-1
From $90
View →Generation 2 · GLP-1 + GIP
Tirzepatide
The one in Mounjaro and Zepbound
~21%avg. body weight lost in SURMOUNT-1
From $230
View →Generation 3 · GLP-1 + GIP + glucagon
Retatrutide
Exclusively at Deer
~28%avg. body weight lost in TRIUMPH-1
From $150
View →Trial averages, not a prediction. These are the average results across participants in each cited clinical trial. Individual results vary and depend on eligibility, adherence, dosing, health factors, nutrition, and activity.
In practice
What taking one looks like
One small injection a week with a pen, into the skin of the stomach or thigh, using a needle finer than a sewing pin. Every protocol starts at a low dose and steps up gradually over weeks; starting low is how the digestive system adjusts, and it is why the first weeks are about tolerability rather than maximum effect.
The most common side effects across all three medications are digestive: nausea, constipation, or an unsettled stomach, most noticeable after a dose increase and usually easing as the body adapts. This guide is general research context, not medical advice; talk to a licensed healthcare professional about your own health.
Next up: more guides on choosing, first injections, and titration.