BlessUp Peptide Library · Metabolic & Appetite
Retatrutide, tirzepatide, semaglutide, and cagrilintide are not four versions of one drug. They pull different levers on the same gut-brain circuit.
More receptors is not automatically more for you. Here is how to read the whole class honestly.
Retatrutide Phase 2, Jastreboff 2023, N Engl J Med (48-week 12 mg group). Full citations at the end.
You have seen the names traded like tiers of the same thing: semaglutide, then tirzepatide, then retatrutide, each sold as the newer and stronger one, with cagrilintide floating alongside as the up-and-comer. It reads like a ladder, where the top rung is simply the best.
Here is the honest version. These are not four strengths of one drug. They are different combinations of levers on one shared circuit, the gut-brain axis that decides how hungry you feel and how your body handles fuel. Semaglutide pulls one lever. Tirzepatide pulls two. Retatrutide pulls three. Cagrilintide pulls a different one entirely. More levers can mean more weight lost on average, and it can also mean more to feel and more to monitor. The right question is never "which is strongest," it is "which set of levers fits my body, my goal, and my safety picture." We do honest, not hype, so let us take it slowly.
Read this first
This is education, not medical advice, and it does not replace your own clinician or your own labs. Of this class, semaglutide and tirzepatide are approved medicines in many places; retatrutide is investigational and still in trials; cagrilintide is investigational, studied mostly in combination. Any dose named here is an example for discussion, never a prescription. These compounds carry real contraindications, covered below. This is educational information only and not a recommendation to use, purchase, or dose any compound; it does not replace evaluation by your own licensed provider. Intended for adults 21 and over.
90-second self-check
This does two things: it flags the hard stops that mean this class is not for you, and if you are clear, it points toward the kind of lever that matches your goal. It is education, not a diagnosis or a recommendation to use anything.
Answer honestly. Nothing is stored, and no one sees it but you.
First, the hard stops. Do any of these apply to you? (tap all that are true)
What are you actually weighing this class for?
Any of these in your picture? (tap all that apply)
Is the foundation actually in place? (tap all that apply)
This reflection is education only, not a diagnosis or a recommendation to use any compound. Talk to a licensed provider about your own history and goals.
The basics
When you eat, your gut releases hormones that travel to the brain and pancreas and quietly run the show: they tell you that you are full, they slow how fast the stomach empties, and they sharpen the insulin response to the meal. Two of those gut hormones are called incretins: GLP-1 and GIP. A third pancreatic hormone, glucagon, raises how much energy you burn and helps the liver clear fat. And a fourth, amylin, is released with insulin and reinforces fullness through its own separate receptor.
Every compound in this class is a synthetic hormone shaped to switch one or more of those receptors on and to last for days instead of minutes. That is the entire trick. What changes from one to the next is simply which receptors it hits.
| Compound | GLP-1 | GIP | Glucagon | Amylin | Class |
|---|---|---|---|---|---|
| Semaglutide | ✓ | — | — | — | single |
| Tirzepatide | ✓ | ✓ | — | — | dual |
| Retatrutide | ✓ | ✓ | ✓ | — | triple |
| Cagrilintide | — | — | — | ✓ | amylin |
Cagrilintide is the odd one out on purpose: it works an entirely different receptor, which is exactly why it is being paired with a GLP-1 rather than competing with one. More on that below.
The honest half-truth you will hear
"Retatrutide is just the strongest one, so it is the best." Half true. On average it produces the deepest weight loss in trials, but it is also the least far along, still investigational, hits the most receptors, and adds glucagon effects (a faster heart rate, and a need to watch liver and glucose) that a single agonist does not. Strongest on the group average is not the same as best for one specific person. The class rewards matching, not maxing.
The number everyone wants
Here are the headline average results from the pivotal trials, placed side by side. Read them as directional, not as a fair head-to-head: the trials differ in length (48 to 72 weeks), in population, and in design, so this is the shape of the class, not a photo finish. Every bar is a real, published, peer-reviewed number.
Average body-weight reduction at the top studied dose
Least-squares mean change from baseline, placebo-subtracted effects are larger still. Longer bar = more average weight lost.
Retatrutide: Jastreboff 2023 NEJM (Phase 2). Tirzepatide: SURMOUNT-1, Jastreboff 2022 NEJM. CagriSema: REDEFINE 1, Garvey 2025 NEJM. Semaglutide: STEP 1, Wilding 2021 NEJM. Doses and durations differ; not a head-to-head.
Notice the shape. Adding the second receptor (GIP) took semaglutide's roughly 15% up toward 21%. Adding the third (glucagon) nudged it further, toward 24%. And pairing a GLP-1 with the amylin lever (cagrilintide plus semaglutide) landed right alongside the dual agonist. The levers stack, but with clearly diminishing returns and rising complexity. That trade is the whole story of this class.
Two honest footnotes to that chart
First, only one real head-to-head exists in this whole class: a diabetes trial where the dual agonist beat the single one on both blood sugar and weight. Everything else is separate trials placed side by side. Second, the triple agonist's later, larger Phase 3 results have been announced but not yet peer-reviewed, so we are quoting its published Phase 2 figure of about 24%, not the higher topline numbers you may have seen in headlines. When the number is not fully validated yet, we say so.
Under the hood
A meal triggers incretin release from the gut. These hormones reach the brain's appetite centers and register satiety, so hunger and food-seeking quiet down.
The same signaling slows gastric emptying, so food leaves the stomach more gradually. You feel full longer and eat less at the next meal, which is also where most of the nausea comes from.
At the pancreas, insulin is released in step with glucose and glucagon is tuned, smoothing blood sugar. The added levers (GIP, glucagon, amylin) each deepen or broaden this metabolic effect.
The reason these compounds work for days instead of minutes, unlike your own gut hormones that clear in a couple of minutes, is that each is engineered to resist breakdown and to bind albumin in the blood, which parks it in circulation. That is why the whole class is dosed roughly once weekly rather than with every meal.
The design logic
Stacking receptors is not showing off. Each added lever is there for a specific, honest reason, and each brings its own cost.
Adding GIP to GLP-1 is not just a louder copy of the same signal. GIP appears to improve insulin sensitivity and fat metabolism, and it adds its own appetite signal on top, so it deepens the average weight effect rather than duplicating it. This is the tirzepatide idea, and its trial results (about 21%) are why the dual approach took off.
Glucagon gets a bad name from diabetes, but at the receptor it raises energy expenditure and helps the liver mobilize and clear fat. Add it on top of GLP-1 and GIP and you get retatrutide, with the deepest weight loss seen so far. Its standout is liver fat: in a Phase 2a liver substudy, liver fat fell by roughly 81 to 82% at the higher doses over 24 weeks. The cost of the extra lever: a dose-related rise in heart rate and a need to watch glucose and the liver more closely.
Cagrilintide does not touch the incretin receptors at all. It mimics amylin, the fullness hormone co-released with insulin, hitting satiety through a separate pathway. Paired with a GLP-1, it hits fullness from two independent directions at once, which is the logic behind combining it with semaglutide rather than running it solo.
The pattern to hold onto
Every lever you add can buy more average weight loss and adds something to feel and to monitor. There is no free receptor. The most advanced-looking option is not automatically the wisest one for a given person.
The four, with honest pros and cons
Same circuit, different levers, and honestly, different stages of proof. Tags show the receptor set: single, dual, triple, or amylin.
The single GLP-1 agonist that opened this whole era, and the one with the longest real-world track record in this class.
Honest read: the sensible, best-proven starting point for most people. Weekly, titrated slowly from 0.25 mg toward 2.4 mg. Half-life about 7 days.
Adds the GIP lever to GLP-1. The dual approach that pushed average results into the low twenties.
Honest read: a strong step up in effect for someone who needs more than the single lever delivers. Weekly, titrated from 2.5 mg toward 15 mg. Half-life about 5 days.
Adds the glucagon burn lever on top of both incretins. The deepest weight loss recorded to date, and the least far along.
Honest read: the most powerful and the least proven. Exciting, but the newest and the one that most demands a knowledgeable provider. Weekly, titrated from about 1 mg upward in trials. Half-life about 6 days.
Not an incretin at all. A long-acting amylin analog that hits fullness through its own receptor, built to pair with a GLP-1 rather than replace one.
Honest read: the interesting complement, not a competitor. Its role is combination therapy. Weekly dosing; very long half-life, roughly a week or more.
The practical part people skip
Each of these is engineered to linger in the blood for days, which is what makes weekly dosing possible and what makes patient titration non-negotiable: a compound this long-lived cannot be rushed, because you cannot un-take this week's dose.
Approximate half-life, in days
How long the compound lingers. All support once-weekly dosing; none should be escalated quickly.
Approximate elimination half-lives from the OnePin compound reference and product labeling. Individual figures vary; the point is the shared once-weekly cadence.
The universal rule the whole class shares: start low, hold, and only step up if the current dose is well tolerated and has stopped delivering. Chasing the top dose fast is how people turn a manageable compound into a miserable week. And because each is a distinct GLP-class compound, the standard practice is to pin it on its own, never mixed in a syringe with other peptides.
What you will actually feel
Across this entire class, the common adverse events are gastrointestinal: nausea, vomiting, diarrhea, and constipation, plus reduced appetite and sometimes reflux. In the trials these were mostly mild to moderate, were worst during dose escalation, and settled with time. They are not a mysterious reaction, they are the direct result of the mechanism, slowed stomach emptying and dialed-down appetite, turned up a little too far. That is also why they track so closely with how fast you escalate.
The higher-lever compounds tend to bring more of this on average, and retatrutide adds one non-GI item worth naming: a dose-related increase in heart rate from the glucagon lever, which peaked and then eased in the trial. The practical throughline is the same for all four: most of the misery is preventable by going slow, eating smaller and lower-fat meals during escalation, staying hydrated, and holding a dose rather than forcing the next step.
When gut symptoms are NOT just the mechanism
Ordinary nausea that eases between doses is expected. Severe, persistent abdominal pain, especially pain that bores through to the back with vomiting, is different. That is the pancreatitis picture, and it is a stop-and-get-seen situation, not a push-through-it one. The safety section below spells out where the real lines are.
The most important section here
This is the part that matters more than any weight-loss number. Some of these are absolute lines for the whole class, not "go slower" but "not without a professional, and in some cases not at all."
The GLP-1 class carries a boxed warning built on rodent thyroid C-cell tumors. Anyone with a personal or family history of medullary thyroid carcinoma, or with Multiple Endocrine Neoplasia type 2, should not use these compounds. This is a firm line, not a caution.
Pancreatitis has been reported with this class, and a prior history raises the stakes. A past episode is a reason to avoid these or to proceed only under close specialist supervision. New severe abdominal pain on therapy is a stop-and-be-evaluated event.
Rapid weight loss and this class both raise gallstone risk. Existing gallbladder disease is a real caution, and new right-upper-abdominal pain, especially after fatty meals, deserves evaluation.
These compounds slow stomach emptying on purpose. In someone whose stomach already empties too slowly, that can tip into a genuine problem. Significant gastroparesis is a reason to steer clear.
This class is not for use in pregnancy or breastfeeding, and it is generally stopped well before a planned conception. Because it can also affect how oral medicines are absorbed, it can interact with the reliability of oral contraception, one more reason this belongs in a provider conversation.
A diabetic-retinopathy signal was seen with semaglutide and warrants attention in people with diabetic eye disease. And combining this class with insulin or a sulfonylurea can drive blood sugar too low, so those regimens need a provider to adjust them.
The one rule under all of it
None of these compounds is a solo project. The contraindications are real, the titration is unforgiving of shortcuts, and the investigational members are not fully characterized. A knowledgeable provider is not the cautious add-on here, it is part of doing this at all.
The cost nobody puts on the label
When weight comes off quickly, a meaningful share of it can be lean tissue, muscle and other fat-free mass, not just fat. This is true of rapid weight loss in general, and this class produces rapid weight loss, so it applies here across the board. Losing muscle you did not mean to lose is how people end up lighter but weaker, with a slower metabolism that makes the weight easier to regain later.
Here is the honest part: the single biggest lever you personally control is the foundation below, enough protein and real resistance training. That is not optional garnish, it is what decides whether the weight you lose is fat or muscle, and it works no matter which compound you use. You will sometimes hear the amylin lever floated as a muscle-friendly option, and it is an interesting idea worth watching, but the evidence that cagrilintide protects lean mass better than the others is still early and thin. Do not treat it as a shortcut around the protein and the training. Nothing is. Some people also pair the class with a growth-hormone secretagogue to push back on lean-mass loss, which is community practice rather than a proven combination, covered honestly in the HGH deep-dive.
Put it together
There is no universally best lever, only the best fit for a person and a goal. Two questions sort most of it.
First question
Second question
The move most people skip
Start at the lowest effective lever, not the strongest one. You can always add or step up. You cannot easily walk back a rough escalation on a compound that lingers for a week. Matching beats maxing, every time.
The foundation under everything
When appetite drops hard, protein is the first thing people under-eat, and it is the exact thing that protects muscle during weight loss. Anchoring meals around adequate protein is the highest-leverage habit on this entire class. Eat the protein even when you are not hungry for it.
Protein supplies the material; lifting gives the body a reason to keep the muscle. Regular resistance training is the other half of keeping the weight you lose as fat rather than lean tissue. Cardio is fine, but the muscle-protecting work is the strength work.
Most nausea is a meal-size and meal-fat problem meeting a slowed stomach. Smaller, more frequent, lower-fat meals take the edge off the GI effects far more than any supplement will.
Slowed digestion plus reduced intake is a recipe for dehydration and constipation. Deliberate fluids and steady fiber keep the gut moving and blunt two of the most common complaints in one move.
Short sleep raises appetite hormones and works directly against everything this class is doing. Steady sleep, limited alcohol, and consistent meal timing quietly make the compound work better and feel better.
Cutting through the noise
The genuinely supported base of a good result on this class. This is what keeps the loss mostly fat and protects the metabolism. Boring, and it works.
Sensible support when you are simply eating much less: fiber and fluids for the gut, electrolytes for the same reason, and basic micronutrient cover during a low-intake stretch.
Marketed as gentle versions of these compounds. They are not equivalent, the evidence is thin, and treating them as a substitute mostly wastes money and time.
The whole safety of this class lives in slow, patient titration. A product whose pitch is speeding that up is selling you the exact mistake to avoid.
Turn this into action
Have I honestly ruled out every hard stop: thyroid C-cell or MEN2 history, pancreatitis history, and pregnancy or trying to conceive?
Am I choosing the lowest lever that fits my goal, or reaching for the strongest name because it sounds like the best?
Is my protein and resistance training actually in place, so the weight I lose is fat and not muscle?
Am I set up to titrate slowly and hold, rather than chasing the top dose fast?
Is a knowledgeable provider genuinely involved, especially if I am considering the investigational members?
Bring these to your visit
Given my history, is any member of this class off the table for me, and which lever fits my goal best?
What titration schedule do you want me on, and at what point do we hold rather than step up?
If I am on insulin, a sulfonylurea, or oral contraception, how should those be adjusted?
What symptoms should make me stop and call you right away?
A few situations are not "go slower," they are "stop and be seen."
Ordinary nausea eases between doses. Pain that bores through to your back, a neck lump, or a swelling-and-breathing reaction are different animals. When in doubt, be seen.
The BlessUp take
The mechanism here is genuinely good and genuinely simple: hand the gut-brain circuit a signal that lasts for days instead of minutes, and appetite, fullness, and fuel handling all shift. The confusion is entirely in the marketing, which stacks these into a ladder and implies the top rung is best for everyone. It is not. Semaglutide is the best-proven and simplest. Tirzepatide adds a lever and real extra effect with a solid track record. Retatrutide is the most powerful and the least proven, still investigational, and asks the most of both you and your provider. Cagrilintide is not a competitor at all, it is a different door that shines alongside a GLP-1. The honest move is to clear the hard stops first, then choose the lowest lever that fits your goal, build the protein-and-training foundation that decides whether you lose fat or muscle, titrate slowly, and do the whole thing with a provider who knows this class. That is not the timid choice. It is the one that actually works.
The evidence
Headline weight-loss figures are the published least-squares mean results from each compound's pivotal trial, retrieved from PubMed. Trials differ in length, dose, and population, so comparisons are directional. Half-life figures are approximate, from product labeling and the OnePin compound reference.
Citations retrieved from PubMed. Retatrutide and cagrilintide are investigational; their long-term safety is not fully characterized. This report is an honest educational map of the class, not a dosing sheet or a recommendation to use any compound.