HGH Fragment 176-191 vs Petrelintide
Comprehensive side-by-side comparison of mechanisms, dosing, side effects, and research
Also: Frag 176-191, HGH Frag
HGH Fragment 176-191 is exactly what it sounds like: a short tail-end piece of the human growth hormone molecule, amino acids 176 through 191. The idea was to keep the fat-burning part of growth hormone while ditching the parts that raise blood sugar and IGF-1. The bare fragment has never been tested in a controlled human trial. Its modified cousin, AOD-9604, did go through real obesity trials, and the blunt result is that it was very safe but did not produce meaningful weight loss. It is banned in sport by WADA.
Also: ZP8396
Petrelintide is a long-acting amylin analog from Zealand Pharma, co-developed with Roche, designed as a once-weekly injection for obesity. The pitch is gentler weight loss than GLP-1 drugs but with far less nausea and vomiting. Two phase 2 trials read out positively in 2026 (up to 10.7% weight loss at 42 weeks), and a roughly 7,000-person phase 3 program has started. It is not approved anywhere.
Key Comparison Insights
- Both peptides belong to the Weight Loss category, suggesting similar primary applications.
- Petrelintide has stronger research evidence (Human Trials) compared to HGH Fragment 176-191 (Animal Studies).
Detailed Comparison
| Attribute | HGH Fragment 176-191 | Petrelintide |
|---|---|---|
| Category | Weight Loss | Weight Loss |
| FDA Status | Not FDA Approved | Not FDA Approved |
| Clinical Status | Pre I II III IV FDA | Pre I II III IV FDA |
| Mechanism of Action | This fragment is the C-terminal portion of growth hormone, the segment researchers linked to its effects on fat metabolism. The cleanest early data (Wu and Ng, 1993, rat fat tissue) found the closely related hGH 177-191 matched whole growth hormone at blocking new fat formation (antilipogenic) but had no significant direct fat-breakdown (lipolytic) effect. Later mouse work with AOD-9604 reported more fat oxidation, apparently without binding the growth hormone receptor itself. That is the selling point: because it does not act on the GH receptor, it does not raise IGF-1, does not promote tissue growth, and does not impair glucose handling the way full growth hormone can. Some research points to beta-3 adrenergic signaling in fat tissue, but the human mechanism is not nailed down. | Amylin is a hormone your pancreas releases alongside insulin after meals. It acts on the brainstem to make you feel full sooner, slows stomach emptying, and curbs glucagon after eating. Zealand says amylin signaling also helps restore sensitivity to leptin, the body's long-term fullness signal. Native amylin is unusable as a drug because it clumps into fibrils and lasts minutes, so petrelintide was engineered to stay stable at neutral pH, avoid fibril formation, and last a week. That stability also means it can be co-formulated with other peptides, which is why Roche plans to combine it with its own GLP-1/GIP drug. The theory is that amylin gives more of a natural fullness feeling than GLP-1 drugs do, with fewer GI side effects; the tolerability part looks real so far, the bigger-picture claims still need phase 3. |
| Common Dosing | 250-500 mcg daily 1-2x daily, fasted | Not publicly disclosed (once-weekly trial doses) Once weekly |
| Administration | Subcutaneous injection on empty stomach | Subcutaneous injection once weekly |
| Typical Duration | 8-12 weeks | 16 weeks (phase 1b) to 42 weeks (phase 2) in completed trials |
| Best Time to Take | Before bed or morning (fasted) | Same day each week |
Possible Side Effects May vary by individual |
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| Research Summary | The animal data looked promising and the human data deflated it, which is the whole story here. One caveat up front: every human result below comes from AOD-9604, the tyrosine-capped version, not the bare 176-191 fragment sold today. In obese mice (Endocrinology, 2001), both growth hormone and AOD-9604 reduced body-weight gain and increased fat oxidation, without the blood-sugar problems of full GH. A small 12-week phase 2 human study of AOD-9604 generated the early headline, with the 1 mg group losing modestly more weight than placebo. But the larger, better-powered phase 2b trial of roughly 500 obese adults over 24 weeks failed to show a significant weight-loss advantage over placebo, and the developer abandoned obesity development. What survived is the safety record: across about six trials and roughly 900 people, AOD-9604 was as well tolerated as placebo, with no IGF-1 rise and no glucose effects (Journal of Endocrinology and Metabolism, 2013). So the closest human data say safe, and not a meaningful fat-loss drug. | A 16-week phase 1b trial (48 people) reported up to 8.6% mean weight loss at the highest dose versus 1.7% on placebo, with no early plateau. The phase 2 ZUPREME-1 trial (493 people with obesity or overweight, mean BMI 37) reported in March 2026 up to 10.7% mean weight loss at 42 weeks versus 1.7% on placebo. That is clearly less than semaglutide or tirzepatide produce, but tolerability stood out: no vomiting at the maximally effective dose, and side-effect dropouts (4.8%) no higher than placebo (4.9%). ZUPREME-2 (220 people with obesity and type 2 diabetes) reported in October 2026: 7.4-9.2% weight loss at 28 weeks versus 2.0% on placebo, placebo-adjusted HbA1c drops of 0.61-0.88 points, and GI dropouts of 1.9% versus 1.7%. Roche and Zealand have started phase 3a (ZUPREME-3, -4 and -5, about 7,000 people in total, including a cardiovascular-disease population). Honest take: a well-tolerated, moderate-strength drug whose real value may be as a combination partner, and the full peer-reviewed phase 2 data are still pending. |
Frequently Asked Questions: HGH Fragment 176-191 vs Petrelintide
What is the difference between HGH Fragment 176-191 and Petrelintide?
HGH Fragment 176-191 is a weight loss peptide that hgh fragment 176-191 is exactly what it sounds like: a short tail-end piece of the human growth hormone molecule, amino acids 176 through 191. the idea was to keep the fat-burning part of growth hormone while ditching the parts that raise blood sugar and igf-1. the bare fragment has never been tested in a controlled human trial. its modified cousin, aod-9604, did go through real obesity trials, and the blunt result is that it was very safe but did not produce meaningful weight loss. it is banned in sport by wada. Petrelintide is a weight loss peptide that petrelintide is a long-acting amylin analog from zealand pharma, co-developed with roche, designed as a once-weekly injection for obesity. the pitch is gentler weight loss than glp-1 drugs but with far less nausea and vomiting. two phase 2 trials read out positively in 2026 (up to 10.7% weight loss at 42 weeks), and a roughly 7,000-person phase 3 program has started. it is not approved anywhere. The main differences lie in their mechanisms of action and clinical applications.
Which is better, HGH Fragment 176-191 or Petrelintide?
Neither is universally "better" - the choice depends on your specific goals. HGH Fragment 176-191 is typically used for weight loss purposes, while Petrelintide is used for weight loss. Always consult with a healthcare provider to determine which may be appropriate for your situation.
Can HGH Fragment 176-191 and Petrelintide be used together?
Some peptide protocols combine multiple compounds for synergistic effects. However, using HGH Fragment 176-191 and Petrelintide together should only be considered under medical supervision, as both compounds have their own side effect profiles and potential interactions. Research on their combined use may be limited.