# Growth Hormone Axis Peptide FAQ — Tesamorelin, MOTS-c, CJC-1295 — Peptide Research Protocols

> Frequently asked questions about three Growth Hormone Axis research peptides — tesamorelin, MOTS-c and CJC-1295 — answered from the peer-reviewed literature, with citations.

Precise, citation-anchored answers to the questions readers most often bring to these three GH axis research peptides.

## What is tesamorelin?

Tesamorelin is a synthetic 44-amino-acid analogue of human growth hormone-releasing hormone (GHRH), modified at its N-terminus with a trans-3-hexenoic acid group to resist enzymatic breakdown. It binds the GHRH receptor on pituitary somatotroph cells, stimulating pulsatile growth hormone release, which in turn drives hepatic IGF-1 production and preferential lipolysis of visceral fat. The FDA approved it in 2010 for reducing excess abdominal fat in HIV-infected adults with antiretroviral-related lipodystrophy [2]. No FDA approval exists for any other indication.

## What does tesamorelin do?

In controlled trials in HIV-infected adults, tesamorelin consistently and significantly reduces visceral adipose tissue. A 2026 meta-analysis of five RCTs found a mean reduction of 27.71 cm² in visceral fat, a 4.28% reduction in hepatic fat fraction, and a 1.42 kg increase in lean body mass [1]. A pivotal Phase 3 study in 412 patients found visceral fat fell 15.2% with tesamorelin versus a 5.0% increase in placebo, and triglycerides fell by 50 mg/dL [6]. In healthy men, two weeks of tesamorelin raised IGF-1 by 181 µg/L without significantly affecting insulin sensitivity [4].

## How does tesamorelin work?

Tesamorelin binds the GHRH receptor on pituitary somatotroph cells, activating a Gs/cAMP/PKA signalling cascade that stimulates both GH synthesis and pulsatile GH secretion. Released GH stimulates hepatic IGF-1 production. Together, GH and IGF-1 promote lipolysis — the breakdown of stored fat — with a preferential effect in visceral (abdominal organ) fat. Because tesamorelin works by amplifying the body's own GH pulses rather than introducing exogenous GH, it preserves the pulsatile rhythm of GH secretion [4]. The N-terminal hexenoyl modification blocks the enzyme DPP-IV, extending plasma stability compared to native GHRH.

## Will tesamorelin help me lose belly fat?

In its studied population — HIV-infected adults on antiretroviral therapy who have developed lipodystrophy — tesamorelin produces statistically significant and clinically meaningful reductions in visceral fat in multiple controlled trials [1][6]. However, visceral fat reaccumulates within weeks of stopping the drug [5], and the trials establishing those effects were conducted specifically in HIV patients, not in the general population. Whether tesamorelin produces comparable fat reduction in people without HIV lipodystrophy is mechanistically plausible but unestablished by large controlled trials [2]. This desk cannot recommend use for any individual or indication.

## What does the MOTS-c peptide do?

MOTS-c is a 16-amino-acid mitochondrial-derived peptide that primarily activates AMPK — a central cellular energy-sensing enzyme — by inhibiting folate-cycle enzymes, which raises AICAR and triggers AMPK signalling. This improves glucose handling and insulin sensitivity in skeletal muscle [10]. Under metabolic stress it translocates to the nucleus, where it regulates antioxidant and metabolic gene expression [12]. A 2024 study identified casein kinase 2 (CK2) as a direct binding target, with tissue-specific CK2 modulation accounting for effects on muscle glucose uptake and atrophy prevention [8]. In aged mice, exogenous MOTS-c significantly improved treadmill performance, grip strength and gait [11].

## What are the negative side effects of MOTS-c?

There are no published controlled human trials of exogenous MOTS-c, so a human adverse-effect profile does not exist in the peer-reviewed literature [9]. The cautions in the published record are primarily about the limits of the evidence itself: no validated human pharmacokinetics, no established safe dose, and population-level evidence from anti-doping bodies that MOTS-c is treated as a prohibited metabolic modulator [10]. There is also a potentially meaningful ancestral/genetic variation — the m.1382A>C mtDNA variant is associated with a pro-diabetogenic phenotype, suggesting that effects may not be uniform across all individuals [10]. This site does not give medical advice.

## Is MOTS-c legal to buy?

MOTS-c is not an approved drug or dietary supplement in any major jurisdiction, and it is sold by research-chemical suppliers for laboratory research use only. Whether purchasing it is legal for a given individual depends on the jurisdiction and intended use; in most countries purchasing research chemicals for personal laboratory use occupies a regulatory grey area. For athletes subject to anti-doping rules, MOTS-c is treated as a prohibited metabolic modulator by bodies including USADA/WADA, and use can result in sanctions regardless of legal status in the athlete's country. This site does not advise on purchasing or use.

## How often do you inject MOTS-c?

This desk does not provide dosing information for MOTS-c or any other compound on this site. There is no published controlled human trial establishing a safe or effective dose or injection frequency for exogenous MOTS-c. Dosing protocols circulating online for MOTS-c are not derived from controlled human studies and have no peer-reviewed basis [10]. The animal studies that established biological activity used a wide range of doses and schedules in rodents, and rodent parameters cannot be directly extrapolated to human use [11]. For any medical question, consult a licensed clinician.

## What is CJC-1295?

CJC-1295 is a synthetic analogue of the first 29 residues of human growth hormone-releasing hormone (hGRF(1-29)), carrying four amino-acid substitutions that protect it from enzymatic degradation. Its most widely studied form — CJC-1295 DAC — also carries a Drug Affinity Complex (DAC) moiety that binds covalently to serum albumin, extending plasma half-life to approximately six to eight days [16]. A shorter-acting form without the DAC (Modified GRF 1-29) exists but is pharmacokinetically very different; community sources often conflate the two [13].

## What does CJC-1295 do?

CJC-1295 binds the GHRH receptor on pituitary somatotrophs and stimulates pulsatile growth hormone release and downstream IGF-1 production, just as native GHRH does — but because of its extended half-life, a single dose maintains elevated GH and IGF-1 for days to weeks. In healthy adults, a single subcutaneous dose produced two- to ten-fold increases in mean plasma GH for six days or more and 1.5- to 3-fold increases in IGF-1 for 9–11 days; after multiple doses IGF-1 remained above baseline for up to 28 days [16]. Pulsatile GH secretion was not disrupted [17]. There are no controlled human efficacy trials for any clinical outcome.

## Is CJC-1295 safe?

CJC-1295 has not been evaluated for safety across a full clinical development programme. Published human data are limited to pharmacokinetic studies in healthy adults, where it was described as generally well tolerated in the small cohorts studied [16][17]. A patient death occurred during the ConjuChem Phase 2 programme that led to discontinuation of the DAC programme, though a causal link to CJC-1295 was not established in the public record [13]. Beyond those early studies, the long-term safety profile is unknown; sustained GH/IGF-1 elevation raises theoretical concerns about fluid retention, insulin sensitivity changes and oncologic risk [13]. FDA advisory committee materials cite safety concerns for GH secretagogues as a class [13]. This desk cannot assess safety for any individual.

## How much CJC-1295 should I take?

This desk does not provide dosing recommendations for CJC-1295 or any other compound. The only published human dose-response data for CJC-1295 come from pharmacokinetic studies in healthy adults using 30–90 µg/kg administered subcutaneously [16][17] — studies designed to measure hormone curves, not to establish a therapeutic dose for any condition. CJC-1295 has not been approved for any use, so there is no regulatory-approved dose. Dosing protocols widely circulating online are not derived from controlled efficacy trials. Consult a licensed clinician for any medical question.

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Peer-reviewed literature on GH axis peptides, summarised without dosing guidance, clinical claims, or products.