Best Peptides for Fat Loss and Muscle Gain in 2026: Evidence-Based Rankings

Overview

Body recomposition — losing fat while simultaneously gaining muscle — is one of the most sought-after fitness outcomes and one of the most physiologically challenging to achieve. Traditional nutrition science holds that fat loss requires a caloric deficit while muscle gain requires a caloric surplus, making simultaneous achievement difficult through diet and exercise alone. Certain peptides may facilitate recomposition by creating hormonal and metabolic conditions that favor fat mobilization while supporting muscle protein synthesis. Growth hormone axis stimulation is particularly relevant because GH promotes lipolysis while preserving or increasing lean mass through IGF-1-mediated protein synthesis. GLP-1/GIP agonists combined with resistance training may also achieve recomposition, though lean mass preservation during aggressive weight loss remains a challenge. This article is educational only and does not constitute medical advice. Body composition goals should be discussed with a qualified healthcare provider.

How We Ranked These Peptides

This ranking is based on four criteria applied consistently across every compound: (1) the quality and size of available human clinical evidence, (2) the specificity of the mechanism to simultaneous fat loss and muscle gain (body recomposition), (3) the current regulatory and approval status, and (4) the reproducibility of reported outcomes. Peptides backed by large randomized controlled trials rank above those with only phase 2 data, which in turn rank above compounds supported only by animal studies or anecdotal reports. This hierarchy is not a recommendation — it is an evidence-quality snapshot designed to help readers distinguish well-studied compounds from speculative ones. Individual suitability depends on medical history, contraindications, and the guidance of a qualified healthcare provider.

How Peptides May Support Body Recomposition

Body recomposition through peptides relies on creating a metabolic state where fat is preferentially mobilized for energy while muscle protein synthesis is maintained or enhanced. Growth hormone axis peptides (CJC-1295, ipamorelin, MK-677) are particularly relevant because GH has dual effects: it promotes lipolysis in adipose tissue while stimulating IGF-1, which drives muscle protein synthesis. Tesamorelin has demonstrated this recomposition effect clinically — reducing visceral fat while maintaining lean mass. GLP-1/GIP agonists like tirzepatide produce dramatic fat loss but with concurrent lean mass reduction; combining these agents with resistance training and adequate protein intake may shift the composition of weight lost toward a greater proportion of fat. AOD-9604 was specifically designed to isolate the fat-metabolizing effects of GH without the anabolic component, though in a recomposition context, the anabolic component would actually be desirable.

#1: Tirzepatide (Zepbound) (FDA-Approved — With Resistance Training)

Tirzepatide produces the most absolute fat mass reduction of any available compound, but its recomposition potential depends heavily on the concurrent use of resistance training and adequate protein intake to preserve lean mass. Body composition analyses from the SURMOUNT program show significant fat mass reduction with some lean tissue loss. Emerging research is exploring whether structured resistance training during tirzepatide treatment can produce net recomposition — meaningful fat loss with lean mass maintenance or even gain. The dual GIP/GLP-1 mechanism may offer some lean mass preservation advantage over GLP-1-only agonists. For individuals with significant excess body fat, tirzepatide combined with progressive resistance training represents one of the most evidence-supported recomposition strategies, though achieving simultaneous muscle gain (rather than just preservation) during aggressive weight loss remains physiologically challenging.

• Evidence level: Strong for fat loss; emerging evidence for recomposition when combined with resistance training; no dedicated recomposition trials published
• Key finding: The SURMOUNT-1 trial demonstrated 22.5% total weight loss at 72 weeks, with the GIP receptor component potentially contributing to comparatively better lean mass outcomes than GLP-1-only agonists — studies combining tirzepatide with structured resistance training are ongoing
• Mechanism: Dual GIP/GLP-1 receptor agonist producing major caloric deficit through appetite suppression; GIP receptor activation may influence adipocyte metabolism and potentially support lean mass retention
• Administration: Once-weekly subcutaneous injection with dose escalation
• Regulatory status: FDA-approved for weight management (Zepbound) and type 2 diabetes (Mounjaro)
• Key consideration: Recomposition with tirzepatide requires intentional resistance training and high protein intake to counteract the lean mass catabolism that accompanies aggressive caloric deficit

#2: Tesamorelin (Egrifta) (FDA-Approved for Visceral Fat)

Tesamorelin may be the peptide most inherently suited for body recomposition because its mechanism naturally produces simultaneous fat reduction and lean mass preservation. By stimulating endogenous GH release, tesamorelin promotes lipolysis (particularly in visceral fat depots) while the resulting IGF-1 elevation supports muscle protein synthesis. Clinical trials in its approved indication demonstrated 15-18% visceral fat reduction with concurrent maintenance or modest increases in lean body mass — a true recomposition effect. Unlike GLP-1 agonists, tesamorelin does not work through appetite suppression or caloric deficit, which means the recomposition it produces is mechanistically driven (GH-mediated fat mobilization plus GH/IGF-1-mediated anabolic signaling) rather than deficit-driven. This makes it particularly interesting for individuals who want to improve body composition without significant weight loss.

• Evidence level: Strong for the recomposition effect in its approved indication — clinical trials demonstrated simultaneous visceral fat reduction and lean mass maintenance/increase
• Key finding: A 2010 clinical trial showed tesamorelin reduced visceral fat by 15-18% while preserving lean body mass over 26 weeks — demonstrating a true body recomposition effect through GH axis stimulation
• Mechanism: GHRH analog that stimulates endogenous pulsatile GH release, promoting lipolysis in adipose tissue while supporting lean mass through GH- and IGF-1-mediated protein synthesis
• Administration: Daily subcutaneous injection
• Regulatory status: FDA-approved for visceral adiposity reduction in HIV-associated lipodystrophy (Egrifta); used off-label for body composition optimization in some clinical settings
• Key consideration: The recomposition effect is most pronounced for visceral fat; subcutaneous fat reduction is more modest. The overall magnitude of body composition change is smaller than with GLP-1 agonists but with a more favorable fat-to-lean ratio

#3: CJC-1295 + Ipamorelin (GH Secretagogue Stack)

The CJC-1295/ipamorelin combination targets body recomposition through the same GH/IGF-1 axis mechanism as tesamorelin but via a different pharmacological approach — stimulating GH release from both the GHRH and ghrelin receptor pathways simultaneously. The sustained GH elevation from CJC-1295 combined with the selective, pulsatile release from ipamorelin creates a hormonal environment that promotes lipolysis while supporting protein synthesis. In clinical settings, practitioners frequently discuss this combination for recomposition in patients who want to improve body composition without the dramatic appetite suppression and total weight loss of GLP-1 agonists. While neither compound has been formally studied for recomposition outcomes in a controlled trial, the well-established effects of GH on body composition provide a strong physiological rationale.

• Evidence level: Moderate for individual GH-elevating effects; theoretical for body recomposition — no formal recomposition trials with this specific combination
• Key finding: CJC-1295 produces sustained IGF-1 elevation while ipamorelin provides selective GH release — the combination creates a hormonal profile associated with fat mobilization and lean mass support in GH research literature
• Mechanism: Dual-receptor GH secretagogue stack that elevates GH and IGF-1, promoting lipolysis in adipose tissue and protein synthesis in skeletal muscle simultaneously
• Administration: Subcutaneous injection, typically administered two to three times daily in clinical practice protocols
• Regulatory status: Neither compound is FDA-approved; both are sold as research peptides and used in some clinical body composition settings
• Key consideration: The recomposition rationale is based on GH physiology rather than direct clinical trial evidence for this specific combination — results will depend heavily on concurrent training, nutrition, and individual GH response

#4: Ipamorelin (Standalone)

Ipamorelin as a standalone GH secretagogue is relevant to recomposition because its selectivity avoids two effects that can undermine body composition goals: appetite stimulation (which complicates fat loss) and cortisol elevation (which promotes muscle catabolism and fat storage). By producing GH elevation without these counterproductive effects, ipamorelin creates a more favorable hormonal environment for recomposition compared to non-selective secretagogues like GHRP-6 or MK-677. The GH elevation promotes lipolysis while the consequent IGF-1 increase supports muscle protein synthesis — the two simultaneous effects needed for recomposition. While the magnitude of these effects from ipamorelin alone is modest compared to exogenous GH, the selective mechanism provides a cleaner pharmacological profile for body composition goals.

• Evidence level: Moderate — human studies confirming selective GH release; body composition effects inferred from GH physiology rather than direct ipamorelin recomposition trials
• Key finding: A 1998 study demonstrated that ipamorelin produces GH elevation without cortisol, prolactin, or appetite stimulation — avoiding hormonal effects that counteract both fat loss and muscle preservation goals
• Mechanism: Selective ghrelin receptor agonist that elevates GH without appetite stimulation or cortisol release, creating hormonal conditions favorable for simultaneous fat mobilization and muscle protein synthesis
• Administration: Subcutaneous injection, typically administered two to three times daily
• Regulatory status: Not FDA-approved; available through some compounding pharmacies and research peptide suppliers
• Key consideration: Standalone ipamorelin produces more modest GH elevation than the CJC-1295 combination, and the body composition effects require adequate training stimulus and nutrition to manifest

#5: MK-677 (Ibutamoren)

MK-677 has direct clinical evidence for body recomposition: a 1997 RCT showed a 1.1 kg increase in fat-free mass over just 2 months in elderly subjects without exercise. The sustained 24-hour GH elevation and oral dosing convenience make it appealing for recomposition. However, MK-677's significant appetite-stimulating effect is a complication for the fat loss side of recomposition — increased caloric intake can offset the fat-mobilizing effects of GH elevation. Additionally, potential insulin resistance with chronic use may impair both glucose-dependent fat metabolism and nutrient partitioning. For recomposition specifically, MK-677 may be most useful when appetite can be managed through dietary discipline, and when insulin sensitivity is monitored. Its proven fat-free mass increase in clinical settings, combined with its oral convenience, keeps it relevant for recomposition despite these limitations.

• Evidence level: Moderate to strong — human RCTs demonstrating fat-free mass increases and body composition improvements; appetite and insulin effects may complicate recomposition applications
• Key finding: A 1997 RCT demonstrated a 1.1 kg increase in fat-free mass and improved body composition in elderly subjects over 2 months of MK-677 treatment — one of the few direct demonstrations of peptide-induced lean mass gain in humans
• Mechanism: Orally active ghrelin receptor agonist producing sustained GH and IGF-1 elevation that promotes both lipolysis and muscle protein synthesis — though appetite stimulation may counteract fat loss
• Administration: Oral capsule taken once daily — a significant convenience advantage over injectable peptides for long-term recomposition protocols
• Regulatory status: Not FDA-approved; sold as a research chemical
• Key consideration: The appetite stimulation and potential insulin resistance effects of MK-677 can undermine the fat loss component of recomposition — dietary discipline and metabolic monitoring are essential if used for this purpose

#6: AOD-9604

AOD-9604's role in recomposition is limited by its design: it was specifically engineered to isolate the fat-metabolizing fragment of growth hormone without the growth-promoting (anabolic) effects. This means AOD-9604 may promote lipolysis without providing the IGF-1-mediated muscle protein synthesis support that makes full GH secretagogues more suitable for recomposition. For individuals seeking pure fat loss without anabolic effects, this specificity is the point. For recomposition, however, the absence of muscle-building support means AOD-9604 would need to be combined with another anabolic stimulus (training, other peptides, or adequate protein intake) to achieve simultaneous fat loss and muscle gain. Phase 2 clinical data showed modest fat reduction without effects on IGF-1 or insulin, confirming its selective mechanism.

• Evidence level: Moderate — phase 2 human data showing fat reduction without anabolic signaling; useful for the fat loss component of recomposition but does not provide muscle-building support
• Key finding: Clinical studies confirmed that AOD-9604 promotes fat metabolism through beta-3 adrenergic pathways without affecting IGF-1 levels — supporting fat loss but not providing the anabolic component needed for full recomposition
• Mechanism: Growth hormone fragment (amino acids 177-191) that stimulates lipolysis without activating the IGF-1 axis — addresses the fat loss component of recomposition but not the muscle growth component
• Administration: Subcutaneous injection in clinical and practice settings
• Regulatory status: Not FDA-approved; available through some compounding pharmacies and research suppliers
• Key consideration: For true recomposition, AOD-9604 would need to be paired with a separate anabolic stimulus — it addresses only the fat metabolism side of the body composition equation

How to Evaluate Body Recomposition Peptide Claims

Body recomposition peptide claims should be evaluated with particular attention to whether the compound addresses both sides of the equation — fat loss and muscle gain — or only one. True recomposition evidence requires body composition measurements (DEXA, CT) showing simultaneous fat mass decrease and lean mass increase, not just changes in one compartment.

• Demand body composition data showing simultaneous fat mass decrease AND lean mass increase — a compound that only reduces fat (AOD-9604) or only increases lean mass is not a recomposition agent by itself
• Evaluate whether studies controlled for training and nutrition — body recomposition outcomes are highly dependent on resistance training stimulus and protein intake, which are confounding variables
• Be cautious of assuming that GH elevation automatically produces recomposition — the magnitude of GH-induced body composition change depends on baseline hormonal status, age, training state, and nutrition
• Distinguish between recomposition in GH-deficient or obese populations (where it is more readily achievable) and in lean, well-trained individuals (where it is much more difficult)
• Consider that scale weight may not change during recomposition — fat lost and muscle gained may offset each other, making body composition measurements essential
• Assess the timeframe — recomposition is a slow process; studies shorter than 3 months may not capture meaningful simultaneous changes in both compartments

Important Safety and Legal Considerations

Body recomposition protocols often involve combining multiple peptides, resistance training, and specific nutritional strategies, creating a complex intervention with limited safety data. The interaction between GH axis stimulation and the metabolic demands of simultaneous fat loss and muscle building has not been systematically studied.

• GH axis stimulation may impair insulin sensitivity, which could paradoxically hinder body recomposition by reducing glucose disposal efficiency in muscle tissue
• Combining GLP-1 agonists (for fat loss) with GH secretagogues (for muscle preservation) is discussed in practice but has not been studied for safety in controlled trials
• Adequate protein intake is essential during recomposition to support muscle protein synthesis — peptide use without sufficient dietary protein is unlikely to produce lean mass gains
• Water retention from GH elevation can mask both fat loss and muscle gain on body weight measurements, making body composition tracking with DEXA or similar methods important
• Overtraining risk may be elevated when combining caloric restriction (for fat loss) with progressive resistance training (for muscle gain) — recovery capacity is compromised in caloric deficit regardless of peptide support
• Regular metabolic monitoring (glucose, insulin, IGF-1, lipids) is advisable for any recomposition protocol involving GH axis peptides

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References

1. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1) (2022) — PubMed
2. Tesamorelin for the Treatment of Visceral Adiposity in HIV-Infected Patients (2010) — PubMed
3. Prolonged Stimulation of Growth Hormone and IGF-I by CJC-1295 (2006) — PubMed
4. Ipamorelin — A Selective Growth-Hormone-Releasing Peptide (1998) — PubMed
5. MK-677 Stimulation of Growth Hormone in Healthy Elderly Subjects (1997) — PubMed
6. AOD9604 — A Novel Anti-Obesity Compound (2001) — PubMed