# Weight loss: what the research says Weight-loss research on the quiz items is uneven. Human clinical trials of the molecules behind the two GLP research peptides, RTA and TRZ, recorded group-average falls in body weight against placebo in trials of 48 to 80 weeks. Those trials were mostly developer-funded, enrolled screened adults and tested trial drug product, not research material. For BPC-157, searches on 14 October 2026 found animal tendon studies and no weight-loss study in people. Your body weight moves with meals, sleep, activity and the gut hormones released after you eat, so one reading on the scale tells only part of the story. Weight research follows hundreds of people for many months instead, beside a placebo group that received no active treatment. The [RTA study guide](/learn/retatrutide/retatrutide-study-findings) and the [TRZ study guide](/learn/tirzepatide/tirzepatide-study-findings) report those trials for the two GLP research peptides in the quiz. The quiz also lists BPC-157 under Weight loss, for its answer about losing weight while looking after tendons. The [BPC-157 study guide](/learn/bpc-157/bpc-157-study-findings) reports rat tendon experiments and no weight-loss study in people, and the [BPC-157 hub](/learn/bpc-157) collects its other guides. This page reports what studies found and what kind of study each one was. ## What did human trials find on body weight for the GLP research peptides? Human trials of the molecules behind both GLP research peptides recorded larger average weight falls than placebo. In the RTA guide's main Phase 3 trial, of 2,339 adults without diabetes, average weight fell 17.6% to 25.0% across three treatment groups over 80 weeks, against 3.9% on placebo (*New England Journal of Medicine*, 2026). In the TRZ guide's main 72-week trial, of 2,539 adults with obesity or overweight, it fell 15.0% to 20.9%, against 3.1% (*New England Journal of Medicine*, 2022). The developer funded both trials, and both report group averages that do not predict any one person's result. The [RTA study guide](/learn/retatrutide/retatrutide-study-findings) adds a 48-week Phase 2 trial of 338 adults with obesity, in which the highest group averaged a 24.2% fall against 2.1% on placebo (*New England Journal of Medicine*, 2023). Averages also hide the spread between people. In the 72-week trial of 2,539 adults, 85% to 91% of the three treatment groups had lost at least 5% of body weight, against 35% on placebo, so some people in each group lost less (*New England Journal of Medicine*, 2022). The [TRZ study guide](/learn/tirzepatide/tirzepatide-study-findings) sets out those shares beside the averages. ## What do the weight-loss studies not show? The weight-loss studies leave four gaps. First, the human trials tested trial drug product in screened volunteers, not research-use material. Second, the developer funded every trial in the RTA guide, and most trial abstracts in the TRZ guide name the maker as funder. Third, each result is a group average that cannot predict one person's change. Fourth, searches on 14 October 2026 found no human weight-loss study of BPC-157. Entry rules narrow each result further. The 2,339-adult trial excluded people with diabetes, a history of pancreatitis or recent use of weight-loss drugs, so its averages describe that group (*New England Journal of Medicine*, 2026). Its Phase 3 papers were read as abstracts, the short summaries, so their full side-effect tables are not reported here. ## What happened to body weight after trial treatment stopped? Body weight rose again in the trial that tested stopping. In a trial from the TRZ guide, 670 adults with obesity or overweight first completed a 36-week lead-in; those then switched to placebo regained an average of 14.0% from week 36 to week 88, while those who continued lost a further 5.5% (*JAMA*, 2024). The abstract names no funder, and the result applies only to adults who completed the lead-in. ## Why is BPC-157 listed under Weight loss in the quiz? BPC-157 is listed for the quiz answer "Lose weight and protect my tendons as I get active", and its research concerns tendons, not body weight. The FDA's July 2026 briefing and PubMed records searched on 14 October 2026 did not find a study of BPC-157 for weight loss in people. Its tendon findings come from rats, such as a cut-Achilles-tendon study reporting a higher load before failure (Staresinic et al., *Journal of Orthopaedic Research*, 2003). That 2003 rat study gave no group size in its abstract, and a rat result does not establish what happens in a person. In a 2026 study of 32 rats with repaired Achilles tendons, BPC-157 had higher maximum-load values than control without statistical significance (Biçer et al., *Joint Diseases and Related Surgery*, 2026). A 2025 systematic review included 35 preclinical studies and one clinical study (Vasireddi et al., *HSS Journal*, 2025). More than 80% of BPC-157 papers come from one research group, a 2026 review estimated (Mateescu et al., *Pharmaceutics*, 2026). The [BPC-157 study guide](/learn/bpc-157/bpc-157-study-findings) sorts the evidence by type. ## Comparison Each row is one item the Weight loss quiz can suggest, with the quiz's own finding line, the type of study behind it, its research guide and its product page. Rows follow the quiz order, not the strength of the evidence. | Quiz item | What studies found | Study type | Read the research | Product | | --- | --- | --- | --- | --- | | RTA (GLP research peptide) | Linked to weight loss in human clinical trials. Still experimental and not approved by the TGA. | Human clinical trials | [RTA study guide](/learn/retatrutide/retatrutide-study-findings) | [RTA (GLP research peptide)](/shop/retatrutide) | | TRZ (GLP research peptide) | Linked to weight loss in human clinical trials, reported as group averages. | Human clinical trials | [TRZ study guide](/learn/tirzepatide/tirzepatide-study-findings) | [TRZ (GLP research peptide)](/shop/tirzepatide) | | BPC-157 | Linked to faster tendon healing in animal studies. Human evidence is limited. | Animal studies | [BPC-157 study guide](/learn/bpc-157/bpc-157-study-findings) | [BPC-157](/shop/bpc-157) | ## Frequently asked questions ### Do weight-loss trial results apply to research peptides? No. The human weight results come from trial drug product given to enrolled participants under clinical trial conditions (*New England Journal of Medicine*, 2026 and 2022). Research-use material is a laboratory compound, and none of those trials tested it. ### Did every trial participant lose weight? No trial in these guides reports that everyone lost weight. In the RTA guide's Phase 2 obesity trial, with 338 adults over 48 weeks, 92% of the second-lowest group lost at least 5% of body weight, so some lost less, and 27% on placebo also reached 5% (*New England Journal of Medicine*, 2023). ### Is RTA approved in Australia? No. On 14 September 2026 the TGA reported that the molecule behind RTA is in human clinical trials and has not been approved by the TGA or any comparable regulator. RTA, a GLP research peptide, is research-use material and not a medicine. ### Has BPC-157 been studied for weight loss in people? Not in the records checked. A PubMed search on 14 October 2026 returned three BPC-157 records with obesity, adipose or fat-mass terms: two reviews of peptides and a survey of websites, and none was a weight-loss trial. The FDA's July 2026 briefing reported none either. ## Citations - Jastreboff AM et al.. New England Journal of Medicine. 2026, online 29 September. DOI: 10.1056/NEJMoa2604169 - Jastreboff AM et al.. New England Journal of Medicine. 2023;389(6):514-526. DOI: 10.1056/NEJMoa2301972 - Jastreboff AM et al.. New England Journal of Medicine. 2022;387(3):205-216. DOI: 10.1056/NEJMoa2206038 - Aronne LJ et al.. JAMA. 2024;331(1):38-48. DOI: 10.1001/jama.2023.24945 - Staresinic M et al.. Journal of Orthopaedic Research. 2003;21(6):976-983. DOI: 10.1016/S0736-0266(03)00110-4 - Biçer O et al.. Joint Diseases and Related Surgery. 2026;37(3):822-837. DOI: 10.52312/jdrs.2026.2951 - Vasireddi N et al.. HSS Journal. 2025;21(4):485-495. DOI: 10.1177/15563316251355551 - Mateescu DM et al.. Pharmaceutics. 2026;18(5):625. DOI: 10.3390/pharmaceutics18050625 [Take the quiz: Weight loss](https://stack.formlaboratories.com) The quiz lists each research item with its study record. Research use only — not for human or animal use. ## Articles in this hub --- Canonical page: https://www.formlaboratories.com/learn/weight-loss Form Laboratories - Perth-based research-use-only peptide supplier, shipping Australia-wide. - Site guide for agents: https://www.formlaboratories.com/llms.txt - Sitemap: https://www.formlaboratories.com/sitemap.xml - Full catalogue: https://www.formlaboratories.com/shop - Contact: hello@formlaboratories.com All materials are supplied for laboratory research use only - not for human or veterinary use, and nothing on this site is medical advice.