WHAT IT IS MADE OF
One chain. Precise modifications.
Three receptors.
Retatrutide is a synthetic peptide: a chain of 39 amino acids, modified at specific positions, with an attached lipid component.
- 01
The 39-amino-acid chain
Each sphere is one unit of the chain. Select a position to see its name.
- 02
Three modified positions
Aib · 2, 20 / αMeL · 13. These are modified amino acids within the same chain. [11]
- 03
A lipid anchor: C20
Attached to lysine 17 through a linker. It supports albumin binding and persistence in circulation. [11]
The molecule as a whole activates three receptor types. GLP-1, GIP and glucagon are not three separate ingredients. [2]
Select a receptor for the explanation in the body. Receptors and effects are not limited to a single organ.
The attachment point for the linker and C20 lipid component.
The diagram shows composition, not atomic geometry. One sphere = one amino acid. Colours are explanatory.
Cα traces from experimental structure PDB 8YW3: retatrutide (gold) and the GLP-1 receptor (blue). The 30 peptide positions resolved in this model are shown; positions 31–39, the C20 branch and G proteins are not drawn.
PDB 8YW3 ↗ · Li et al., Cell Discovery (2024) ↗01 / HUMAN DATA
Measured outcomes.
Context matters.
Each chart has its own study, participants and time frame. Group averages do not predict an individual result.
NEJM · 2023 · N = 338
Two milestones,
within one trial.
Adults with obesity, or overweight and a comorbidity, without diabetes. Adjusted mean weight change from baseline.
Original publication ↗Lines connect published milestones only; they are not weekly measurements. Doses identify study arms, not recommendations.
See all groups
| Group | 24 wk | 48 wk |
|---|---|---|
| Placebo | −1.6% | −2.1% |
| 1 mg | −7.2% | −8.7% |
| 4 mg | −12.9% | −17.1% |
| 8 mg | −17.3% | −22.8% |
| 12 mg | −17.5% | −24.2% |
The 4 and 8 mg groups combine initiation strategies as reported.
NEJM · 2026 · N = 2,339
A larger trial.
An 80-week endpoint.
TRIUMPH-1: adults with obesity, without diabetes. The treatment-regimen / intention-to-treat analysis accounts for treatment discontinuation.
Original publication ↗MEAN WEIGHT CHANGE · WEEK 80
These are different groups, not steps in an administration schedule. The 80-week data do not extend the 2023 trial chart.
02 / BEYOND WEIGHT
What changes
on the inside?
MASLD · N = 98 · MRI-PDFF
Liver fat
Mean relative reduction at 24 weeks, 12 mg group; placebo +0.3%. Phase 2a substudy, participants with at least 10% liver fat at baseline.
This is MRI-measured liver fat, not liver size or proof of fibrosis resolution. Particles are decorative, not tissue imaging.
Nature Medicine · 2024 ↗DXA · TYPE 2 DIABETES
Lean mass
deserves attention too.
Participants who completed treatment and both DXA scans, out of those enrolled in the substudy. Follow-up: 36 weeks.
The proportion of lean mass loss was comparable to that reported with other obesity treatments. This does not mean muscle loss is absent.
Body-composition study ↗03 / AGE & CONTEXT
Age is one part
of the story.
This selection changes the explanations. It does not calculate personal risk or determine treatment eligibility. We do not save this selection.
Adult data do not describe adolescents.
The studies presented here do not provide a safety or efficacy estimate for people under 18. We do not extrapolate the charts to children or adolescents.
A wide range is not a single risk profile.
The 2023 phase 2 trial enrolled ages 18–75; mean age was 48.2. Aggregate data do not establish identical safety at every age. Illnesses, other medicines, nutrition and frailty matter. [4]
Insufficient evidence for this profile.
These sources do not provide robust estimates specific to people over 80. Age 80 is not a demonstrated biological safety threshold. Frailty and muscle reserve require individual assessment.
Nutrition & frailty
ADA discusses dehydration, undernutrition and muscle loss in older adults using GLP-1 therapies. This is class context, not a proven retatrutide risk percentage. [10]
Low doses, mg, ml and “units”: what do they mean?
Some commenters describe better appetite control at doses they call low. Those posts do not establish a suitable dose or escalation schedule for a reader. In the phase 2 trial, protocol-specified increases occurred at four-week intervals with monitoring; this is research context, not a schedule to follow. [4]
mg describes the amount of substance; ml describes solution volume. Syringe “units” depend on its scale; they are not mg of retatrutide. Without the exact concentration and syringe type, “10 units” does not identify a dose in mg. Syringe capacity cannot be assumed either. For a prescribed dose, check the conversion with a clinician or pharmacist.
The FDA has documented conversion errors with compounded semaglutide. This source explains the risk of confusing units, not a conversion for retatrutide. [14]
04 / SAFETY & TOLERABILITY
Side effects.
Clearly explained.
What trials have observed, how people describe symptoms, and when to seek help. The safety profile is still being evaluated; this is not a complete list or an estimate of your personal risk.
CLINICAL DATA
Digestion
Nausea, diarrhoea, constipation and vomiting. In phase 2, gastrointestinal events were the most frequent, usually mild or moderate and dose-related.
NEJM · 2023 ↗Skin sensation
Dysesthesia means unusual, unpleasant sensations such as burning or tingling. It was reported in TRIUMPH-1; it does not automatically mean an allergy.
Lilly · TRIUMPH-1 ↗Heart rate
In phase 2, heart-rate increases were dose-related, peaked at week 24 and declined afterwards. A study average does not automatically explain an individual’s palpitations.
NEJM · 2023 ↗How often were they reported?
TRIUMPH-1 · 2,339 adults · 80 weeks
| Reported event | Placebo | 4 mg | 9 mg | 12 mg |
|---|---|---|---|---|
| Nausea | 14.8% | 28.6% | 38.4% | 42.4% |
| Diarrhoea | 13.5% | 25.2% | 34.1% | 32.0% |
| Constipation | 10.9% | 23.8% | 25.9% | 26.1% |
| Vomiting | 4.8% | 10.6% | 22.8% | 25.3% |
| Dysesthesia · altered sensation | 0.9% | 5.1% | 12.3% | 12.5% |
| Urinary tract infections | 5.3% | 7.5% | 8.8% | 8.4% |
| Upper respiratory tract infections | 11.6% | 14.2% | 12.2% | 13.1% |
| Discontinuation due to adverse events | 4.9% | 4.1% | 6.9% | 11.3% |
One participant may report several events; percentages should not be added. An event occurring during a trial does not, on its own, prove that the molecule caused it. Other trials may differ in population and duration.
PERSONAL ACCOUNTS
How people describe the experience
Examples from public comments, not independently verified. They describe the authors’ experiences, not reaction frequencies or a demonstrated causal link.
Fatigue and sensitive skin
One person describes fatigue, sensitive skin and less strength at the gym after an initially energetic period. The same discussion includes accounts of headaches and afternoon fatigue.
Racing pulse and dizziness
An author describes a raised resting pulse, dizziness and weakness. Comments do not establish the diagnosis or cause; these symptoms should not automatically be considered a normal adjustment.
Some accounts describe no discomfort
Under the retatrutide video, one person reports reduced appetite and feeling well without unpleasant effects. The comment was written after the first administration, so it describes only the beginning.
GENERAL GUIDANCE · WHEN TO SEEK HELP
Immediate medical help
Trouble breathing, sudden tongue or throat swelling, fainting, chest pain, or sudden or severe abdominal pain: seek emergency help. Call your local emergency number; in Romania, call 112.
Do not ignore persistent symptoms
Repeated vomiting, reduced urination and persistent dizziness on standing need prompt medical assessment. Discuss recurring palpitations with a clinician; if they do not stop, or come with chest pain, breathlessness or feeling faint, seek immediate help.
This guidance applies regardless of cause; it does not mean every symptom is an established retatrutide reaction. Do not change treatments based on comments. If you are in a trial, also tell the study team about new symptoms.
05 / COMMUNITY OBSERVATIONS
What communities
are saying.
A look at publicly shared experiences: what people appreciate and how responses differ. These are personal accounts, not independently verified; this selection does not measure how often benefits or side effects occur.
Less mental space taken up by food.
The author says food no longer dominates their day. They describe weight loss and a more manageable routine, even though hunger has not disappeared. For them, the change became more natural than expected.
Moving feels easier after weight loss.
An author who says they took part in TRIUMPH-1 enthusiastically describes returning to ultramarathons: running felt much easier at a lower weight. After the trial, they continued with another treatment and strength training, relevant context for their later progress.
Experiences follow different paths.
The appetite discussion also includes responses below expectations. A 61-year-old with type 2 diabetes says that after switching from tirzepatide they had not yet seen the progress they hoped for and were also questioning the product they used. Individual circumstances differ.
06 / FAQ
Your questions.
Clear answers.
The dossier, explained simply. Open a question for the answer and its source.
What is retatrutide and how does it work?
Retatrutide is an investigational peptide developed by Lilly. One molecule activates three receptor types: GLP-1, GIP and glucagon, involved in appetite and metabolism. It is not a mixture of three peptides.
Source & context ↗How much weight loss has been observed in trials?
In the 2023 phase 2 trial with 338 participants, the 12 mg group had an adjusted mean weight reduction of 24.2% at 48 weeks, compared with 2.1% with placebo. These are group results from a monitored trial, not a personal forecast or dose recommendation. The Outcomes section also presents phase 3 data separately.
Source & context ↗What does research show about liver fat?
In a substudy of 98 participants with metabolic fatty liver disease, the 12 mg group had a mean relative liver-fat reduction of 82.4% at 24 weeks. This percentage refers to the initial amount of liver fat, not body weight. This measurement does not establish a cure for all liver diseases.
Source & context ↗Is only fat lost, or is muscle lost too?
In the body-composition substudy in people with type 2 diabetes, both fat and lean mass decreased. DXA lean mass includes more than skeletal muscle. The proportion of lean-mass loss was similar to other obesity treatments; this does not mean muscle is automatically preserved.
Source & context ↗What adverse effects have been reported?
Trials report nausea, diarrhoea, constipation and vomiting. TRIUMPH-1 also recorded altered skin sensation (dysesthesia), while phase 2 observed increases in heart rate. The Side effects section separately presents trial frequencies, personal accounts and symptoms that need medical help. The safety profile is still being evaluated.
Source & context ↗Explore the Side effects section ↗Where can retatrutide be purchased?
As checked on 14 October 2026, retatrutide is not publicly available as an approved medicine. According to Lilly, access is through its clinical trials, subject to eligibility. MYBB does not recommend buying from the black market or unauthorised suppliers. Checking provenance or an analysis certificate does not replace authorisation and safety evaluation.
Source & context ↗Do milligrams, millilitres and “units” mean the same thing?
No. Milligrams describe substance mass, millilitres describe volume, and syringe markings indicate volume according to the syringe calibration. “10 units” does not automatically mean “1 mg”. Concentration and syringe type matter; this page does not provide conversions or administration instructions. The cited FDA warning concerns errors with compounded semaglutide, not a retatrutide regimen.
Source & context ↗Does the animation show what will happen in my body?
The animation visually explains mechanisms and research findings. It is not a personalised clinical simulation: it cannot predict your weight loss, organ response or adverse effects. Charts present study-group results with the population and duration identified.
07 / SOURCES & METHOD
Keep the connection
to the evidence.
Editorial check: 14 October 2026. Studies, preclinical data, guidelines and accounts are treated separately. A narrative selection, not a systematic review. The cited clinical trials are sponsored by Lilly.
- Lilly · Retatrutide research status · September 2026 ↗
- Cell Discovery · Receptor structures · 2024 ↗
- Cell Metabolism · LY3437943, discovery to clinical proof of concept · 2022 ↗
- NEJM · Obesity, phase 2 · 2023 ↗
- NEJM · TRIUMPH-1, phase 3 · 29 September 2026 ↗
- Nature Medicine · Liver fat, phase 2a · 2024 ↗
- The Lancet Diabetes & Endocrinology · Body composition substudy · 2025 ↗
- The Lancet · Type 2 diabetes, phase 2 · 2023 ↗
- NHS · Severe abdominal pain & collapse ↗
- ADA · Older Adults: Standards of Care in Diabetes · 2026 ↗
- Drug Testing and Analysis · Retatrutide structure & analysis · 2026 ↗
- RCSB PDB · 8YW3 · retatrutide–GLP-1R · cryo-EM ↗
- KEGG DRUG · D12430 · Retatrutide sequence ↗
- FDA · Milligrams, millilitres and syringe units · 2024 ↗
- Lilly · TRIUMPH-1 safety data · 6 June 2026 ↗
- NHS · Dehydration ↗
- NHS · Anaphylaxis ↗
- NHS · Heart palpitations ↗
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