Retatrutide and Cagrilintide: Why Are People Combining Them for Food Noise?

How Common Is This Discussion?

It’s a recurring theme. “Reta and cagri” comes up again and again in the WhatsApp groups and online communities we monitor, usually from people who’ve already been on a weight loss jab for a while. Google’s own search suggestions show people are asking about it too, with phrases like “reta and cagri together”, “retatrutide and cagrilintide side effects” and “reta cagri blend reviews”. That tells us there’s real interest. It doesn’t tell us how many people are actually using the two together, and nobody has reliable figures on that.

The hunger side of the story has been studied a little more. A 2026 analysis of Reddit posts looked at 13,589 different Reddit users who described using unapproved retatrutide. Of the 7,823 who mentioned at least one symptom, the researchers list increased appetite first among the most commonly described, followed by tiredness, extra energy and nausea. The study hasn’t been peer reviewed yet, and the authors point out that they couldn’t know what was in people’s products, what doses they used or what else they were taking alongside. So it shows hunger is a common complaint among people using online retatrutide, not why it happens.

What People Are Saying

The story usually goes something like this. In the early weeks, appetite seemed to switch off. Then, gradually, the food noise crept back. For others, it never really went quiet in the first place.

Not everyone has that experience. Some people say retatrutide turned their food noise off within days and kept it that way. Both kinds of story appear in the same groups, sometimes in the same conversation.

When it doesn’t seem to be working, people start looking for something to add. Cagri comes up because it’s said to work on fullness in a different way. Some describe it as “turning the volume down” when reta alone didn’t.

Others ask about ready-mixed “reta-cagri blends” sold online, whether they’re safe, and how they compare with taking retatrutide and cagrilintide separately. And plenty of people are asking a simpler question: is it me, or is it the product?

We can’t verify any of these individual experiences. What we can do is look at what the research says about each part of the story.

Why Doesn’t Retatrutide Quieten Everyone’s Food Noise?

Retatrutide acts on three hormone receptors: GLP-1 and GIP, the two that Mounjaro works on, plus glucagon. (Our retatrutide vs Mounjaro comparison explains the difference.)

It does reduce hunger on average. In a phase 2 trial of 275 adults with type 2 diabetes, people on the middle and higher doses reported bigger drops in hunger and appetite than those on placebo by week 24. On the highest doses, they also felt less hungry and less likely to overeat at weeks 24 and 36.

But the link between feeling less hungry and losing weight was only modest. In other words, appetite is just one part of how retatrutide works. Early research by Eli Lilly, which makes retatrutide, found that in mice the glucagon part added to weight loss by increasing the energy the body uses, rather than by cutting appetite. We don’t yet know how much that applies in people. But it’s one reason retatrutide might not feel like an “off switch” for hunger, even for people it’s working for.

It’s also worth knowing what hasn’t been studied. That appetite trial was in people with type 2 diabetes, it was run by Lilly, and no trial has measured “food noise” itself on retatrutide. People also simply respond differently to these medicines.

There’s one more thing communities rarely talk about. Everything above comes from trials using genuine retatrutide. Anything bought online is a different matter. Not feeling much appetite suppression doesn’t mean a product is fake: even in trials, people on genuine retatrutide responded differently. But with an unlicensed supply, you simply can’t be sure what you’re injecting. This year the MHRA has seized thousands of fake pens labelled retatrutide and tirzepatide, and it hasn’t published what was inside them. That uncertainty is a safety issue in its own right: six cases of liver damage have been linked to grey-market retatrutide.

What Is Cagrilintide, and Why Is It Being Mentioned?

Cagrilintide, or cagri, is a long-acting version of amylin, a hormone your pancreas releases alongside insulin after you eat. Amylin slows how quickly your stomach empties and acts on the brain to help you feel full. That’s a different pathway from GLP-1, the hormone that Wegovy and Mounjaro mimic. It’s why people wonder whether cagri could fill the gap when another medicine isn’t quietening their appetite.

On its own, once-weekly cagrilintide led to average weight loss of up to 10.8% in a phase 2 trial, compared with 3% on placebo. Paired with semaglutide, the active ingredient in Wegovy, as CagriSema, people lost 20.4% of their body weight on average over 68 weeks in the REDEFINE 1 trial, compared with 3.0% on placebo. Stomach side effects such as nausea, vomiting and diarrhoea affected 79.6% of people on CagriSema and 39.9% on placebo, and were mostly mild to moderate and temporary.

So the combination that has been tested in people is cagri with semaglutide, not cagri with retatrutide. For the full picture on cagrilintide, including where it stands in the UK and what’s being sold under its name, see our guide: Cagrilintide UK: What Is Cagri? And for how CagriSema compares with today’s medicines, read CagriSema vs Mounjaro.

What Did the September 2026 Rat Study Find?

On 15 September 2026, researchers at the University of Copenhagen published the first study of retatrutide and cagrilintide given together, in the journal Nature Metabolism. It’s the study behind a lot of the recent “reta and cagri” buzz, so it’s worth looking at properly.

What they did. The team gave the two drugs together, every day for 13 days, to male rats with diet-induced obesity. They compared the pair with each drug on its own at matched doses, and with similar combinations using semaglutide or tirzepatide instead of retatrutide.

What they found. The combination cut body weight and food intake more than either drug alone, and more than the matched combinations with semaglutide or tirzepatide. It also improved cholesterol, triglycerides and insulin levels. Interestingly, extra experiments suggested the bigger weight loss couldn’t be explained by the rats simply eating less.

Why it’s interesting. It supports the idea that the amylin pathway adds something on top of retatrutide’s three hormone targets. The researchers say their results could help guide the design of future single medicines that act on all five receptors at once.

Why it doesn’t tell us it works, or is safe, in people.

• It was in rats, and only male rats. Results in animals often don’t carry over to humans.
• The rats got both drugs daily. Both medicines are being developed as once-weekly injections for people.
• It lasted about two weeks, so it can’t tell us anything about long-term safety. And nobody has measured side effects of this pair in humans.
• The researchers work at a centre funded by the Novo Nordisk Foundation (Novo Nordisk makes cagrilintide), and several authors declare links to Novo Nordisk, Eli Lilly or obesity drug start-ups. That doesn’t make the findings wrong, but it’s worth knowing.

We also checked the main international trials register, and couldn’t find any registered human trial of retatrutide and cagrilintide together.

What About “Reta-Cagri Blends” Sold Online?

Pre-mixed vials and pens sold as “reta-cagri blends” are advertised online, often labelled “for research use only”. It’s easy to see the appeal: one product instead of two.

But these aren’t licensed medicines. No regulator has checked what’s in them, how they were made, or whether the amounts on the label are accurate. And the blend itself has never been tested in people: not by Lilly, not by Novo Nordisk, not by anyone.

The reviews and dosing charts you’ll find online come from sellers or individuals, not trials. We don’t publish dosing information for unlicensed products, and we’d be wary of anyone who does.

There’s also a practical worry about taking retatrutide and cagrilintide together. Both commonly cause stomach side effects, and with CagriSema around four in five people had them. Two medicines that both cause sickness and diarrhoea could plausibly add up, which raises the risk of dehydration. Nobody has measured that for this pair.

What We Do Not Know Yet

• Whether retatrutide and cagrilintide together work, or are safe, in people.
• Whether adding cagri helps with food noise specifically. Food noise hasn’t been measured in trials of either combination.
• Why some people seem to respond less to retatrutide’s effect on appetite than others.
• What’s actually in the products being sold online as reta, cagri or blends.

What This Means For People In The UK

If you’re on a prescribed weight loss medicine like Mounjaro or Wegovy and your food noise has come back, you’re not alone, and it’s worth raising with your prescriber. They can review how your treatment is going.

If you’re using retatrutide bought online, it’s an unlicensed product. Using retatrutide and cagrilintide together from online sellers means two sets of unknowns, plus a combination nobody has tested in people. If you feel unwell, for example being sick a lot or showing signs of dehydration, get medical advice from your GP or NHS 111 and tell them exactly what you’ve been taking. You can report suspected side effects, including from products bought online, through the MHRA’s Yellow Card scheme.

And watch this space. Retatrutide’s large phase 3 trials are reporting, and CagriSema has been submitted to regulators in the US. Our Retatrutide UK guide keeps track of where things stand.

Key Takeaways

• Some people report that retatrutide doesn’t quieten their food noise, and “reta and cagri” has become a common conversation in online groups.
• In trials, retatrutide reduced hunger on average, but appetite is only part of how it works, and people vary.
• Weak appetite suppression doesn’t mean a product is fake, but products bought online may not contain what they claim, which is a safety concern in itself.
• Cagrilintide works on fullness through the amylin pathway. In people it has been tested alone and with semaglutide, not with retatrutide.
• A September 2026 study in rats found the pair reduced weight more than either drug alone. That doesn’t show it’s safe or effective in humans.
• Neither drug is licensed in the UK, and “reta-cagri blends” sold online are untested, unregulated products.

Further Reading

For everything on cagri itself, read our guide Cagrilintide UK: What Is Cagri? For the latest on retatrutide’s trials and UK timeline, see our Retatrutide UK Guide.

Sources

• Petersen J, Merrild C, et al. Cagrilintide and retatrutide combination therapy enhances weight loss and metabolic outcomes in obese male rats. Nature Metabolism, published online 15 September 2026.
• Kanu C, et al. Appetite, eating attitudes, and eating behaviours during treatment with retatrutide in adults with type 2 diabetes. Diabetes, Obesity and Metabolism, 2025.
• Sehgal NKR, et al. Self-reported side effects among Reddit users taking unapproved retatrutide. medRxiv preprint, 2026 (not peer reviewed).
• Coskun T, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist. Cell Metabolism, 2022.
• Lau DCW, et al. Once-weekly cagrilintide for weight management in people with overweight and obesity. The Lancet, 2021.
• Garvey WT, et al. Coadministered cagrilintide and semaglutide in adults with overweight or obesity (REDEFINE 1). New England Journal of Medicine, 2025.
• Fischer SL, Borner T. Beyond GLP-1: amylin-based pharmacotherapy. Pharmacological Research, 2026.