Among peptides for weight loss, retatrutide, tirzepatide and semaglutide have the strongest studies in humans. In large phase 3 trials they lowered body weight by 25.0, 20.9 and 14.9 percent respectively. Tesamorelin has studies on belly fat, not on body weight. HGH Fragment 176-191, MOTS-C and SLU-PP-332 have results mainly from animals. Below we compare all seven molecules from the shop in numbers.
Which weight loss peptides have studies in humans?
Three molecules from the GLP-1 group have phase 3 trials with thousands of participants. The table sets their main results against the placebo group.
| Peptide and dose | Trial | Duration | Weight loss | Placebo |
|---|---|---|---|---|
| Retatrutide 12 mg | TRIUMPH-1, 2,339 people | 80 weeks | 25.0 percent | 3.9 percent |
| Tirzepatide 15 mg | SURMOUNT-1, 2,539 people | 72 weeks | 20.9 percent | 3.1 percent |
| Semaglutide 2.4 mg | STEP 1, 1,961 people | 68 weeks | 14.9 percent | 2.4 percent |
All three are given as a subcutaneous injection once a week. All three results were counted across all participants, including those who stopped treatment. The guide on how GLP-1 and incretins affect body weight explains why these molecules cut appetite so strongly.
How much weight did people lose in the retatrutide trials?
Retatrutide at 12 mg lowered body weight by 25.0 percent after 80 weeks in the TRIUMPH-1 trial. The 9 mg dose gave 23.7 percent and the 4 mg dose 17.6 percent. The results were published in September 2026.
Already in the phase 2 trial the 12 mg dose gave a 24.2 percent fall after 48 weeks. At least 15 percent of body weight was then lost by 83 percent of people on that dose and 2 percent on placebo. The course over the months is shown in the guide on retatrutide results after a month, 3 months and a year.
Does tirzepatide work more strongly than semaglutide?
Yes, in the only head-to-head comparison of the two molecules tirzepatide did better. In the SURMOUNT-5 trial in 751 people with obesity, tirzepatide lowered body weight by 20.2 percent after 72 weeks. Semaglutide gave 13.7 percent over the same time. Waist circumference fell by 18.4 cm with tirzepatide and 13.0 cm with semaglutide.
In SURMOUNT-1, 57 percent of people on 15 mg of tirzepatide lost at least 20 percent of their weight. In STEP 1, half of the people on semaglutide 2.4 mg lost at least 15 percent. A full comparison of the three molecules is given in the guide on whether to choose semaglutide, tirzepatide or retatrutide.
What does tesamorelin do to belly fat?
Tesamorelin reduces visceral fat, the fat around the organs in the abdomen. In a 2007 trial in 412 people with HIV, visceral fat fell by 15.2 percent after 26 weeks. In the placebo group it rose by 5.0 percent over the same time.
Tesamorelin does not, however, clearly change total body weight, because it increases lean mass at the same time. A 2026 meta-analysis of five trials showed no significant fall in BMI. It is a peptide for the figure and the belly, not for the number on the scales, as expanded in the guide on what tesamorelin did to belly fat.
What is known about HGH Fragment 176-191, MOTS-C and SLU-PP-332?
These three molecules have weight loss results mainly from studies in mice. In humans a modified version of the growth hormone fragment called AOD9604 was studied, but it was not approved as a medicine. The history of these studies is described in the guide on HGH Fragment 176-191 and growth hormone.
In mice MOTS-C improved insulin sensitivity and protected against obesity from overfeeding. We found no study in PubMed in which people received MOTS-C for body weight. SLU-PP-332 is not a peptide but a small molecule that mimics exercise, and it too has data only from mice. All three are compared in the guide on MOTS-C, SLU-PP-332 and HGH Fragment 176-191.
How are weight loss peptides tolerated?
The most common complaints with semaglutide, tirzepatide and retatrutide concern the digestive tract. These are mainly nausea and diarrhoea, usually mild and appearing during dose increases. In STEP 1, 4.5 percent of people on semaglutide stopped treatment because of stomach complaints.
In SURMOUNT-1, 6.2 percent of people on tirzepatide 15 mg and 2.6 percent on placebo stopped treatment because of adverse effects. In the phase 2 retatrutide trial, starting at 2 mg instead of 4 mg eased the complaints. The doses over the weeks are described in the guide on retatrutide doses in trials.
Do weight loss peptides work as tablets?
From this group only semaglutide has studies in tablet form. A 50 mg tablet gave a similar weight loss to a 2.4 mg injection, but it uses more than a hundred times more substance per week. The details are collected in the guide on whether semaglutide works better as a tablet or an injection. The other peptides in tablets are described in the guide on peptides in tablets.
What else do GLP-1 peptides change besides weight?
Semaglutide and tirzepatide have studies on the heart, liver, kidneys and sleep, collected in the guide on what these molecules do beyond weight loss. In the SELECT trial in 17,604 people with excess weight and heart disease, heart attack, stroke or cardiovascular death occurred in 6.5 percent of people on semaglutide and 8.0 percent on placebo. This result is described in the guide on what semaglutide did for the heart in the SELECT trial. Results for the liver are collected in the guide on how semaglutide and tirzepatide act on fatty liver.
Where to buy weight loss peptides?
The shop has all three molecules from the GLP-1 group, in vials and in ready pens. The list shows the prices.
- Semaglutide 3 mg Bio-Peptide: 90 EUR.
- Tirzepatide 20 mg Bio-Peptide: 200 EUR, and the 40 mg Nouveaux pen 350 EUR.
- Retatrutide 20 mg Bio-Peptide: 200 EUR, and the 40 mg Nouveaux pen 350 EUR.
- Tesamorelin 10 mg Genheal: 50 EUR.
- HGH Fragment 176-191 5 mg Bio-Peptide: 25 EUR.
- MOTS-C 10 mg Bio-Peptide: 45 EUR.
The cost of a whole month at trial doses is calculated in the guide on how much a month of semaglutide, tirzepatide and retatrutide costs. Semaglutide and tirzepatide are the active substances of prescription medicines, and retatrutide is not yet approved. The products in the shop are material for laboratory research, not a medicine, and treatment decisions are made by a doctor.
Frequently asked questions
Which weight loss peptide works most strongly?
In phase 3 trials retatrutide 12 mg worked most strongly: a 25.0 percent fall in body weight after 80 weeks. Tirzepatide 15 mg gave 20.9 percent after 72 weeks.
How much weight can you lose on semaglutide?
In the STEP 1 trial semaglutide 2.4 mg lowered body weight by 14.9 percent on average, or 15.3 kg, after 68 weeks.
Does tesamorelin make you lose weight?
Tesamorelin reduces belly fat, by 15.2 percent in 26 weeks in the 2007 trial. It does not clearly change total body weight, because it adds lean mass.
Has HGH Fragment 176-191 been studied in humans?
A modified version, AOD9604, was studied in humans and was not approved as a medicine. Results for the fragment itself come from studies in mice.
Are weight loss peptides available as tablets?
Of these, only semaglutide has studies in tablet form. A 50 mg tablet gave a similar weight loss to a 2.4 mg injection once a week.
Sources
- Jastreboff AM, Kaplan LM, Davies MJ et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity (TRIUMPH-1). New England Journal of Medicine, 2026. https://doi.org/10.1056/NEJMoa2604169
- Jastreboff AM, Kaplan LM, Frías JP et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial. New England Journal of Medicine, 2023, 389(6): 514-526. https://doi.org/10.1056/NEJMoa2301972
- Jastreboff AM, Aronne LJ, Ahmad NN et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine, 2022, 387(3): 205-216. https://doi.org/10.1056/NEJMoa2206038
- Aronne LJ, Horn DB, le Roux CW et al. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). New England Journal of Medicine, 2025, 393(1): 26-36. https://doi.org/10.1056/NEJMoa2416394
- Wilding JPH, Batterham RL, Calanna S et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). New England Journal of Medicine, 2021, 384(11): 989-1002. https://doi.org/10.1056/NEJMoa2032183
- Falutz J, Allas S, Blot K et al. Metabolic effects of a growth hormone-releasing factor in patients with HIV. New England Journal of Medicine, 2007, 357(23): 2359-2370. https://doi.org/10.1056/NEJMoa072375
- Badran AS, Helal A, Shata KS, Ayesh H. Body composition, hepatic fat, metabolic, and safety outcomes of Tesamorelin, a GHRH analogue, in HIV-associated lipodystrophy: A meta-analysis of randomized controlled trials. Obesity Research and Clinical Practice, 2026, 20(1): 2-12. https://doi.org/10.1016/j.orcp.2026.01.002
- Lincoff AM, Brown-Frandsen K, Colhoun HM et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT). New England Journal of Medicine, 2023, 389(24): 2221-2232. https://doi.org/10.1056/NEJMoa2307563
- Lee C, Zeng J, Drew BG et al. The mitochondrial-derived peptide MOTS-c promotes metabolic homeostasis and reduces obesity and insulin resistance. Cell Metabolism, 2015, 21(3): 443-454. https://doi.org/10.1016/j.cmet.2015.02.009