Muscle Preservation on GLP-1s: How to Stack Growth Hormone Secretagogues (Ipamorelin, CJC-1295, MK-677) to Prevent Catabolism
Here's a scenario that plays out more often than it should: someone starts Ozempic or Zepbound, loses 30 or 40 pounds over six months, steps on the scale feeling triumphant — and then gets a DEXA scan and finds out that 10 or 15 pounds of what they lost was muscle. The pants fit. The blood sugar is better. But the body composition is less favorable than expected, the metabolism has slowed, and they feel weaker than before. This is the muscle preservation problem on GLP-1 therapy.
Understanding why this happens — at the molecular level — is the first step to preventing it. The second step is knowing what tools actually work to counter it. Growth hormone secretagogues (GHS), specifically ipamorelin, CJC-1295, and the oral compound MK-677 (ibutamoren), have emerged as the most mechanistically rational research tools for addressing GLP-1-induced catabolism. This guide explains the science, the protocols, and the honest state of the evidence.
The Muscle Loss Problem: How Significant Is It?
Let's start with the data, because there's important nuance here. GLP-1 drugs do not directly cause muscle wasting in the way that, say, high-dose corticosteroids do. They do not break down muscle protein through any direct molecular mechanism. What they do is suppress appetite powerfully — and that caloric restriction creates the conditions for lean mass loss.
What Clinical Trials Actually Show
A meta-analysis published in Nutrition, Metabolism and Cardiovascular Diseases (2025) reviewed body composition data from major GLP-1 and dual GLP-1/GIP agonist trials and found:
- GLP-1 receptor agonists were associated with reductions in lean mass averaging approximately 0.86 kg per study, representing roughly 25% of total weight lost
- Fat mass accounted for approximately 75% of total weight loss
- The proportion of lean mass relative to total body weight often remained stable or slightly improved — because fat was lost at a faster absolute rate
A prospective cohort study published in 2025 (News-Medical) with 200 adults on semaglutide or tirzepatide for six months found that patients who received education on resistance training and protein intake showed better muscle retention than those who did not.
So the 25–40% lean mass figure cited in many contexts is real — but it includes water weight, glycogen-bound water, and organ adaptation, not just muscle protein. The actual muscle protein loss is real but smaller in magnitude. Still, over 6–12 months of treatment, it accumulates — and it matters more as weight loss increases.
Who Is at Highest Risk?
- Sedentary individuals who don't pair GLP-1 therapy with resistance training
- Older adults (65+), who already lose muscle at approximately 3–8% per decade (sarcopenia) and have reduced anabolic signaling
- Protein-deficient patients who reduce total food intake without ensuring adequate protein density
- High-dose, aggressive weight loss scenarios where weekly weight loss exceeds ~1% of body weight
The Molecular Mechanism: Why Caloric Restriction Kills Muscle
To understand how to prevent muscle loss, you need to understand the two key molecular pathways that govern muscle protein balance: mTOR and the GH/IGF-1 axis.
mTOR: The Master Switch for Muscle Protein Synthesis
mTOR (mechanistic Target of Rapamycin) is a kinase enzyme that sits at the center of cellular growth decisions. When nutrients are abundant and anabolic signals are present, mTOR is active — it drives protein synthesis, ribosome biogenesis, and cell growth. When energy is scarce, mTOR is suppressed, and the cell shifts into a catabolic maintenance mode.
In muscle tissue specifically, mTOR Complex 1 (mTORC1) is the primary driver of muscle protein synthesis (MPS). The key activators of mTORC1 in muscle include:
- Amino acids — particularly leucine, which directly activates mTOR via the Ragulator complex
- Insulin / IGF-1 signaling — via the PI3K-Akt-mTOR pathway
- Mechanical loading — resistance exercise activates mTOR independently of insulin
When you reduce caloric intake significantly (as GLP-1 drugs cause), several things happen:
- Leucine and other amino acid availability drops → reduced mTOR activation
- Insulin levels fall → reduced PI3K-Akt-mTOR signaling
- If you're sedentary, no mechanical loading signal → mTOR stays suppressed
The result is that muscle protein synthesis drops below muscle protein breakdown (which continues at baseline rates). The net balance becomes negative — muscle loss ensues.
The GH/IGF-1 Axis: The Anabolic Counterbalance
Growth hormone (GH) is the body's primary counter-regulatory hormone to caloric restriction's catabolic effects. GH:
- Stimulates the liver to produce IGF-1, which activates the PI3K-Akt-mTOR pathway in muscle
- Directly promotes lipolysis in adipose tissue — reducing fat breakdown competition with muscle for energy substrate
- Has anti-catabolic effects in muscle independent of IGF-1
- Promotes fat as the primary fuel source during caloric restriction (protein-sparing effect)
In a well-nourished young person, GH levels naturally rise during fasting and caloric restriction — a compensatory mechanism. But in many patients on GLP-1 therapy (who are often older, may have metabolic dysfunction, or have blunted GH secretory capacity), this compensatory GH rise is insufficient to fully offset the catabolic milieu.
This is the biological gap that GH secretagogues fill.
Ipamorelin: The Selective GH Secretagogue
Mechanism Deep Dive
Ipamorelin belongs to the class of growth hormone-releasing peptides (GHRPs). It is a five-amino-acid peptide (pentapeptide) that acts as a ghrelin mimetic — binding the GHS-R1a (growth hormone secretagogue receptor 1a) in the hypothalamus and pituitary gland.
When GHS-R1a is activated by ipamorelin:
- The pituitary somatotroph cells are stimulated to release a pulse of GH
- GH enters the bloodstream and acts on GH receptors in the liver, triggering IGF-1 production
- IGF-1 circulates systemically, activating PI3K-Akt-mTOR in muscle
- GH simultaneously acts on adipose tissue to promote lipolysis
The word "selective" is critical here. Compare ipamorelin to its older cousins — GHRP-2 and GHRP-6:
- GHRP-2 activates GHS-R1a effectively but also significantly elevates cortisol and prolactin — cortisol promotes muscle catabolism and fat storage, directly undermining the goals of a body composition stack
- GHRP-6 is similar to GHRP-2, with the added problem of potently stimulating appetite — the last thing a GLP-1 user needs
Ipamorelin activates GHS-R1a with high selectivity and without meaningful cortisol or prolactin stimulation. This has been confirmed in dose-ranging studies where cortisol and prolactin levels remained essentially unchanged at effective GH-releasing doses. The "clean" GH pulse without hormonal side effects makes ipamorelin uniquely well-suited for the GLP-1 user who is trying to preserve muscle without introducing new hormonal disruptions.
Timing and the GH Pulse Strategy
GH is not released continuously — it is secreted in discrete pulses, primarily during the first few hours of deep slow-wave sleep and in smaller pulses throughout the day. These pulses are influenced by sleep, fasting state, exercise, and feeding.
To optimize ipamorelin's effects:
- Before sleep: Injecting ipamorelin 20–30 minutes before bed aligns with the largest natural GH pulse during slow-wave sleep — amplifying it rather than replacing it. This also improves sleep quality, which is independently important for muscle preservation (sleep deprivation activates muscle proteolysis pathways independently of GH).
- Upon waking / fasted state: A second injection in the morning in a fasted state captures a metabolic window where GH release is naturally elevated and fat oxidation is highest.
- Pre-workout: Some protocols add a third injection before resistance training, capitalizing on the exercise-driven GH synergy.
Evidence Base
Ipamorelin has been studied in preclinical models extensively and in some human Phase 1/2 contexts, primarily demonstrating safety and GH-releasing effectiveness. A pivotal early study (Raun et al., 1998, European Journal of Endocrinology) established ipamorelin's selectivity profile and dose-response in animals. Clinical data on body composition outcomes in the GLP-1 combination context specifically does not yet exist as published RCT data — this remains an area of clinical investigation and off-label practice.
CJC-1295: Amplifying the GH Signal
Mechanism Deep Dive
CJC-1295 is a synthetic Growth Hormone-Releasing Hormone (GHRH) analog. Natural GHRH is a 44-amino-acid hypothalamic peptide that binds GHRH receptors (GHRHR) on pituitary somatotroph cells — a completely different receptor from the GHS-R1a that ipamorelin targets. This is the key to the synergy: they activate parallel, complementary input pathways to GH release.
Natural GHRH has a half-life of only a few minutes — degraded almost immediately by dipeptidyl peptidase-4 (DPP-4, the same enzyme that destroys natural GLP-1). CJC-1295 with DAC (Drug Affinity Complex) solves this problem by incorporating a maleimide linker that allows CJC-1295 to covalently bind to serum albumin (the most abundant protein in blood). This albumin binding extends the half-life from minutes to approximately 6–8 days — enabling twice-weekly or even once-weekly dosing.
The result: CJC-1295 maintains a chronically elevated "background" level of GHRH receptor stimulation, creating a raised baseline for GH secretion. Each ipamorelin injection then creates an acute spike on top of this elevated baseline — a "pulse-and-sustain" pharmacodynamic pattern.
The Combined CJC-1295 + Ipamorelin Effect
A key paper establishing the pharmacokinetics of CJC-1295 (Teichman et al., 2006, Journal of Clinical Endocrinology & Metabolism) showed that a single injection of CJC-1295 produced dose-dependent increases in GH and IGF-1 lasting 6–8 days, with IGF-1 increases persisting significantly at the 14-day mark. Mean GH levels increased 2–10 fold depending on dose.
When this sustained GHRH-receptor activation is combined with ipamorelin's acute GHS-R1a stimulation:
- Peak GH pulse amplitude increases (ipamorelin contribution)
- GH pulse duration extends (CJC-1295 contribution)
- IGF-1 elevation is greater and more sustained than either compound alone
- 24-hour GH area under the curve (a measure of total GH exposure) increases substantially
This translates to:
- More protein synthesis time in muscle (IGF-1 → PI3K-Akt-mTOR)
- Enhanced lipolysis in adipose tissue
- Better recovery between training sessions
- Improved sleep quality through GH's effects on sleep architecture
MK-677 (Ibutamoren): The Oral GH Secretagogue
What Makes MK-677 Different
MK-677 (ibutamoren mesylate) is in its own category: it is not a peptide, but a non-peptide, orally active small molecule that mimics ghrelin at the GHS-R1a receptor — achieving essentially the same mechanism as ipamorelin, but in pill form.
This is significant for practical reasons. Ipamorelin and CJC-1295 require subcutaneous injection. MK-677 is simply swallowed once daily. For patients who are already uncomfortable with the idea of self-injecting (or who are already injecting their GLP-1 drug and don't want additional needles), MK-677 offers comparable GH-stimulating effects with complete convenience.
Mechanism of Action
MK-677 acts as a potent, full agonist at GHS-R1a. It stimulates pulsatile GH release with a duration profile extending across approximately 24 hours from a single daily oral dose — producing more sustained GH and IGF-1 elevation than ipamorelin injections, which have a shorter active window.
The 24-hour GH coverage from MK-677 means IGF-1 levels are elevated throughout the day and night, which maximizes the anabolic window for muscle protein synthesis and fat oxidation continuously.
Clinical Evidence: What Human Studies Show
MK-677 has actually been studied in human clinical trials — more than most research peptides. Key findings:
Nass et al. (2008), Annals of Internal Medicine: 71 healthy older adults (ages 60–81) received oral MK-677 for 12 months vs. placebo.
- GH increased significantly from baseline and remained elevated throughout
- IGF-1 increased approximately 40% (confirming pharmacodynamic engagement)
- Fat-free mass (lean mass, measured by DXA) increased in the MK-677 group vs. controls
- No change in total body fat or visceral fat (suggesting lean mass gains were genuine, not water)
- No change in muscle strength or functional outcomes (suggesting exercise is still required for functional translation)
- Side effects: increased appetite, transient water retention, mild increase in fasting glucose
FDA Pharmacy Compounding Advisory Committee review (2024): The FDA's assessment of MK-677 data across studies confirmed lean body mass increases in multiple trials, alongside concerns about glucose metabolism (MK-677 promotes GH, which is insulin-antagonistic), water retention, and insufficient long-term safety data.
The lean mass preservation signal is real and has been replicated. The absence of strength gains without exercise underscores the "permissive anabolic environment" model — MK-677 creates the hormonal conditions for muscle protein synthesis, but mechanical loading (resistance training) is the required trigger that actually directs that anabolic signal into hypertrophy.
Important Cautions for MK-677
Blood glucose effects: Because GH is insulin-antagonistic, MK-677 raises fasting blood glucose to some degree. In diabetic users on GLP-1 drugs (which lower blood glucose), these effects partially counteract each other — but glycemic variability can increase. Monitoring is essential.
Appetite stimulation: MK-677 activates ghrelin receptors — ghrelin is the primary hunger hormone. Unlike GLP-1 agonists (which reduce appetite), MK-677 increases appetite. This is the opposite of what most GLP-1 users want, and the combination creates a dynamic tension: GLP-1 suppresses appetite strongly; MK-677 partially counteracts this. For most users, the GLP-1 effect dominates, but appetite control may be less consistent than with GLP-1 alone.
Water retention: GH causes some sodium and water retention, which can manifest as bloating, edema, or transient weight gain on the scale (not fat). This is temporary and dose-dependent.
Not for everyone: The FDA has explicitly noted insufficient evidence for MK-677 effectiveness across multiple indications, and has flagged potential serious safety risks for certain populations. Anyone with glucose intolerance, active cancer, or other complicating conditions should not use MK-677 without explicit physician guidance.
Resistance Training: The Non-Negotiable Component
Growth hormone secretagogues create a hormonal environment that is permissive for muscle protein synthesis. They do not directly cause hypertrophy. The mechanical loading signal from resistance training is the required trigger that converts elevated IGF-1 into actual muscle growth.
Why Resistance Training on GLP-1 Is Different
On a GLP-1 drug, your energy levels may feel lower than usual (especially during dose titration), your GI tolerance may limit your training days early on, and your overall caloric intake is reduced — meaning less glycogen availability for high-intensity work. Adapting training accordingly matters:
Frequency: 3–4 sessions per week targeting all major muscle groups. Research supports that 2–3 hard sets per muscle group per session is sufficient for muscle preservation during caloric restriction — you don't need high-volume bodybuilder training.
Progressive overload: Continuing to increase weights or repetitions over time is the key signal telling your body that muscle is needed. Even during caloric restriction, if progressive overload is maintained, muscle loss is substantially blunted.
Protein synthesis windows: Consuming protein (ideally 30–40 g of high-quality protein, rich in leucine) within 2 hours of resistance training maximizes the mTOR activation window when GH secretagogue levels are also active.
Protein Targets: The Other Half of the Equation
For GLP-1 users trying to preserve muscle, protein intake is arguably more important than any peptide stack. The research-supported targets:
- Minimum for muscle preservation during weight loss: 1.2–1.6 g/kg of body weight per day
- Optimal for concurrent training: 1.6–2.2 g/kg/day
- Leucine per meal: At least 2.5–3 g (approximately 30 g of whey protein, 35 g of chicken) to maximally activate mTOR per eating occasion
On GLP-1 therapy, eating enough protein can be challenging because appetite and food volume are suppressed. Practical strategies include protein shakes (easy to consume even when not hungry), prioritizing protein at the start of each meal before appetite fatigue sets in, and higher-protein density foods (Greek yogurt, cottage cheese, eggs, lean meats).
Practical Timing: Organizing the Stack Around Your GLP-1
Here's how a structured approach might look for someone using semaglutide (once weekly) or tirzepatide (once weekly) alongside GH secretagogues:
GLP-1 Injection Day (e.g., Monday):
- Administer GLP-1 agonist as prescribed
- GLP-1 effects on appetite begin/continue through the week
- CJC-1295 injection (if using — 2x weekly)
Daily (if using ipamorelin or MK-677):
- Ipamorelin (100–300 μg SC): Before bed for GH pulse optimization; optionally pre-workout
- OR MK-677 (12.5–25 mg oral): Once daily in the evening (food can be present)
Resistance training days: 3–4x weekly, timed to coincide with protein intake windows
Note on timing with GLP-1: There is no known pharmacokinetic interaction between GLP-1 drugs and GH secretagogues — they work on entirely separate receptor systems. You can inject ipamorelin at any time; it does not need to be separated from GLP-1 injections.
Comparison Table: Ipamorelin vs. CJC-1295 vs. MK-677
| Feature | Ipamorelin | CJC-1295 (DAC) | MK-677 (Ibutamoren) |
|---|
| Drug class | GHRP / Ghrelin mimetic (peptide) | GHRH analog (peptide) | Non-peptide ghrelin mimetic |
| Receptor target | GHS-R1a | GHRH receptor | GHS-R1a |
| Route of administration | Subcutaneous injection | Subcutaneous injection | Oral tablet / capsule |
| Dosing frequency | 1–2x daily | 2–3x weekly | Once daily |
| Half-life | ~2 hours | ~6–8 days | ~24 hours |
| GH secretion pattern | Acute pulses (short-acting) | Sustained baseline elevation | Sustained ~24-hour elevation |
| Cortisol/prolactin effects | None (highly selective) | None | Mild cortisol increase at high doses |
| Appetite effects | Minimal | Minimal | Increases appetite (ghrelin agonism) |
| Blood glucose effects | Mild elevation | Mild elevation | Moderate elevation (insulin antagonism) |
| Water retention | Mild | Mild | Moderate |
| FDA status | Not approved (research use) | Not approved (research use) | Not approved (research use); FDA flagged concerns |
| Best clinical evidence | Preclinical + Phase 1/2 selectivity data | Human PK data (Teichman 2006) | Human RCT data (Nass 2008, 12-month trial) |
| Best used for | Acute GH pulse optimization | Sustained GH baseline + combined with ipamorelin | Oral convenience; when injection aversion exists |
| Key advantage | Clean selectivity, no hormonal side effects | Long-acting; synergistic with ipamorelin | Oral dosing; most human evidence |
| Key disadvantage | Requires twice-daily injection | Requires injection; sustained GH may reduce pulse amplitude over time | Appetite increase; glucose elevation; water retention |
Frequently Asked Questions
Q: How much muscle do you actually lose on GLP-1 drugs like semaglutide or tirzepatide?
A: Clinical trials consistently show that approximately 25–40% of total weight lost on GLP-1 drugs is lean mass, while 60–75% is fat. For a person losing 40 pounds, this might represent 10–16 pounds of lean mass (including water, glycogen, and genuine muscle protein). The actual muscle protein loss is smaller than these numbers suggest, as some lean mass change reflects adaptive remodeling rather than pathologic wasting. Resistance training and adequate protein intake (1.6–2.2 g/kg/day) can substantially reduce this.
Q: Can you gain muscle while losing weight on a GLP-1 drug?
A: True simultaneous muscle gain and fat loss (body recomposition) is difficult and depends on caloric deficit severity, protein intake, training status, and hormonal environment. Beginners or those returning to training after a long break have the best chance of gaining muscle despite a caloric deficit. For most people on GLP-1 therapy, the realistic goal is preserving lean mass rather than gaining it — which is still a significant achievement during active weight loss.
Q: What is the most important thing to preserve muscle on GLP-1 therapy?
A: Adequate protein intake is the single most important factor — specifically, consuming 1.6–2.2 g of protein per kg of body weight daily, with at least 30 g of high-quality protein per meal. The second most important factor is consistent resistance training with progressive overload 3–4 times per week. GH secretagogues and other anabolic interventions are additive to these fundamentals but cannot replace them.
Q: What is ipamorelin and how does it help prevent muscle loss on GLP-1s?
A: Ipamorelin is a selective growth hormone secretagogue that mimics ghrelin at the GHS-R1a receptor, triggering pulsatile GH release from the pituitary without significantly affecting cortisol or prolactin. The resulting GH elevation stimulates IGF-1 production in the liver, which activates the PI3K-Akt-mTOR muscle protein synthesis pathway. This creates an anabolic hormonal environment that counteracts the catabolic effects of GLP-1-induced caloric restriction.
Q: How do CJC-1295 and ipamorelin work differently?
A: Ipamorelin activates the GHS-R1a (ghrelin receptor), producing acute, short-duration GH pulses. CJC-1295 activates the GHRH receptor, producing sustained, long-duration GH baseline elevation (lasting ~6–8 days per injection). Together, they work synergistically: ipamorelin provides peak amplitude for GH pulses, while CJC-1295 elevates the baseline between pulses. The combined GH and IGF-1 exposure is greater than either compound alone, resulting in more effective muscle preservation.
Q: Is MK-677 safe for people with type 2 diabetes on GLP-1 drugs?
A: MK-677 raises fasting blood glucose because growth hormone is insulin-antagonistic. For people with type 2 diabetes on GLP-1 drugs, these effects work in opposing directions — GLP-1 lowers blood sugar; MK-677 partially raises it. This creates glycemic variability that requires careful monitoring. The FDA has flagged MK-677's glucose effects as a safety concern. Diabetic patients should only consider MK-677 under physician supervision with regular glucose and HbA1c monitoring.
Q: Does resistance training boost the effectiveness of GH secretagogues?
A: Yes, significantly. Exercise-induced GH release from resistance training and GH secretagogue-induced release are synergistic — combining them produces greater total GH and IGF-1 exposure than either alone. More importantly, resistance training provides the mechanical loading signal that converts elevated IGF-1 into actual muscle protein synthesis and hypertrophy. GH secretagogues create the hormonal environment; resistance training provides the directional signal that turns that environment into muscle growth.
Q: Why does MK-677 increase appetite if GLP-1 drugs reduce it?
A: MK-677 works by activating ghrelin receptors (GHS-R1a). Ghrelin is the primary hunger hormone — its natural role is to stimulate appetite between meals. So MK-677 inherently increases appetite through its mechanism of action. GLP-1 drugs work through entirely separate pathways (GLP-1 receptors in the hypothalamus and gut) to suppress appetite. The two effects partially counteract each other — in most users, the GLP-1 appetite suppression dominates, but appetite control may be less consistent than on GLP-1 alone.
Q: What is the best time to take ipamorelin relative to a GLP-1 injection?
A: GLP-1 injections (semaglutide, tirzepatide) are once-weekly and their timing relative to ipamorelin is not pharmacokinetically critical — they act on completely different receptors. For ipamorelin, timing is determined by the desired GH pulse timing: before bed to amplify the natural sleep-associated GH pulse, optionally pre-workout, and/or upon waking in a fasted state. These principles apply regardless of when the weekly GLP-1 was administered.
Q: How long does it take to see results from GH secretagogues in terms of muscle preservation?
A: Initial benefits — improved sleep quality, faster exercise recovery, subjective energy improvements — may be noticed within 2–4 weeks of starting ipamorelin or CJC-1295. Measurable body composition changes (preserved lean mass on DEXA compared to expected loss, improved muscle-to-fat ratio) typically become apparent over 8–12 weeks. Full optimization of body composition occurs over 3–6 months, as GH effects on tissue remodeling are cumulative rather than immediate.
Q: Can you use both CJC-1295/ipamorelin and MK-677 together?
A: Technically, ipamorelin and MK-677 both activate the same GHS-R1a receptor — combining them may produce diminishing returns due to receptor saturation, and is generally considered redundant rather than synergistic. The more rational combination is CJC-1295 (GHRH receptor) + ipamorelin (GHS-R1a receptor) for injectable users, or MK-677 alone for those preferring oral-only approaches. Adding CJC-1295 to MK-677 (different receptor) is a legitimate combination, providing both the GHRH-mediated baseline elevation and the ghrelin-mediated acute pulses.
Key Takeaways
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GLP-1 drugs do not directly destroy muscle, but the caloric deficit they create puts the body in a state where 25–40% of weight lost is lean mass — real, cumulative, and metabolically significant.
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mTOR suppression is the core molecular mechanism of catabolism during caloric restriction; restoring anabolic signaling via the GH/IGF-1 axis is the most direct counter-strategy.
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Ipamorelin is the gold standard injectable GHRP: selective for GH release with no cortisol or prolactin elevation, ideal for pre-sleep and pre-workout GH pulses.
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CJC-1295 (DAC) extends GH release via GHRH receptor activation, creating sustained IGF-1 elevation that amplifies and extends ipamorelin's acute effects — the two are synergistic because they target different receptors.
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MK-677 achieves similar GH-stimulating effects via an oral pill once daily, with the advantages of convenience and 24-hour GH coverage — but with the trade-offs of appetite stimulation, potential glucose elevation, and water retention.
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Resistance training and protein intake are non-negotiable fundamentals — GH secretagogues amplify an anabolic environment but cannot create muscle without the mechanical stimulus and amino acid building blocks that training and protein provide.
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Diabetic users must monitor glucose carefully when combining GH secretagogues with GLP-1 drugs, as GH's insulin-antagonistic effects work in opposition to GLP-1's glucose-lowering action.
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None of these compounds (ipamorelin, CJC-1295, MK-677) are FDA-approved for human use; physician supervision with regular lab monitoring is essential for safe use.
Citations & References
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Zhu J, et al. Effect of glucagon-like peptide-1 receptor agonists and co-agonists on lean body mass. Nutrition, Metabolism and Cardiovascular Diseases. 2025. https://www.sciencedirect.com/science/article/abs/pii/S002604952400341X
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Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). New England Journal of Medicine. 2021;384:989-1002. https://pubmed.ncbi.nlm.nih.gov/33567185/
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Nass R, et al. Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults. Annals of Internal Medicine. 2008;149(9):601-611. https://pubmed.ncbi.nlm.nih.gov/18981487/
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Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue. European Journal of Endocrinology. 1998;139(5):552-561. https://pubmed.ncbi.nlm.nih.gov/9849822/
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Teichman SL, et al. Prolonged stimulation of GH and IGF-I secretion by CJC-1295, a long-acting analog of GH-releasing hormone. Journal of Clinical Endocrinology & Metabolism. 2006;91(3):799-805. https://pubmed.ncbi.nlm.nih.gov/16352683/
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Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine. 2022;387(3):205-216. https://pubmed.ncbi.nlm.nih.gov/35658024/
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FDA Pharmacy Compounding Advisory Committee. Ibutamoren mesylate (MK-677) review. 2024. https://www.fda.gov/media/183016/download
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Morton RW, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine. 2018;52:376-384. https://pubmed.ncbi.nlm.nih.gov/28698222/
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News-Medical. Study shows minimal lean muscle mass loss with GLP-1 and GLP-1/GIP therapy for weight loss. April 2025. https://www.news-medical.net/news/20250409/Study-shows-minimal-lean-muscle-mass-loss-with-GLP-1-and-GLP-1GIP-therapy-for-weight-loss.aspx
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Schiaffino S, Mammucari C. Regulation of skeletal muscle growth by the IGF1-Akt/PKB pathway: insights from genetic models. Skeletal Muscle. 2011;1:4. https://pubmed.ncbi.nlm.nih.gov/21798082/
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Tritos NA, Klibanski A. Effects of growth hormone on body composition. Endocrinology and Metabolism Clinics of North America. 2007;36(1):169-180. https://pubmed.ncbi.nlm.nih.gov/17336742/
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van der Lely AJ, et al. Biological, physiological, pathophysiological, and pharmacological aspects of ghrelin. Endocrine Reviews. 2004;25(3):426-457. https://pubmed.ncbi.nlm.nih.gov/15180951/
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Storer TW, et al. Effects of testosterone supplementation on body composition in healthy adults: a meta-analysis. Journal of the Endocrine Society. 2021;5(1):bvaa174. https://pubmed.ncbi.nlm.nih.gov/33319159/
