Side-by-side · Research reference

GHRP-6vsMOTS-c

Side-by-side comparison across mechanism, dosage, evidence, side effects, administration, and stack synergies. Citations on every claim where available.

APhase 1Reviewed10/36 cited

BAnimal-StrongReviewed16/68 cited

GHRP-6

Hexapeptide GHRP · Strong appetite stimulant

100–200 mcgPer doseBowers 1990

Phase 1Evidence levelBowers 1990

~15 minHalf-lifeMalagón 1999

SQ · Multiple sites · 1–3×/day

MOTS-c

Mitokine · Mitochondria-Encoded

5–10 mgWeekly doseLee 2015

AnimalEvidence levelLee 2015 Reynolds 2021

Min–hrsHalf-life

SQ · Variable · 2–3×/week

01Mechanism of Action

Parameter

GHRP-6

MOTS-c

Primary target

Ghrelin receptor (GHS-R1a)Bowers 1990

Mitochondrial 12S rRNA sORF → folate-AICAR-AMPK axisLee 2015

Pathway

GHS-R1a → Gαq → Ca²⁺ → GH release; central appetite driveBowers 2002

Folate cycle inhibition → ↑AICAR → AMPK phosphorylation → PGC-1α upregulationLee 2015 Kim 2018

Downstream effect

GH pulse + strong appetite stimulation; modest IGF-1 elevationBowers 2002

Enhanced fatty acid oxidation, GLUT4-mediated glucose uptake, mitochondrial bioenergetics, anti-inflammationLee 2015

Feedback intact?

—

Stress-responsive, AMPK-dependent nuclear translocationKim 2018

Origin

Synthetic hexapeptide; first-generation GHRP from Bowers groupBowers 1990

Endogenous 16-AA mitokine; mtDNA-encoded; declines with age; upregulated by exerciseReynolds 2021

Antibody development

—

02Dosage Protocols

Parameter

GHRP-6

MOTS-c

Standard dose

100–200 mcg per injectionBowers 1990

5–10 mg / weekLee 2015

Experimental, extrapolated from animal data. No human RCT-derived dose.

Frequency

1–3× per day

2–3× per week

Short half-life may necessitate more frequent dosing for saturation.

Lower / starter dose

50 mcg per dose

2.5–5 mg / week

Recommended due to limited human data.

Evidence basis

Phase 1 + clinical practiceBowers 1990

Animal + anecdotalLee 2015 Reynolds 2021 A first-in-human phase 1 study 2021

Phase 1a/1b CB4211 analog trial completed 2021; no native MOTS-c RCT published.

Duration

8–12 weeks on / 4 off

4–12 weeks (experimental)

Optimal cycle length unknown.

Reconstitution

Bacteriostatic water

Bacteriostatic water, 1–2 mL

10 mg/mL at 1 mL.

Timing

Pre-meal preferred for appetite support

Pre-workout or fasted state preferred

Activity-context amplifies AMPK response.

Half-life

~15 minMalagón 1999

Minutes to hours (estimated)

Systemically unstable; native MOTS-c PK in humans not fully characterised.

03Metabolic / Fat Loss Evidence

Parameter

GHRP-6

MOTS-c

Primary fat target

—

Diet-induced / metabolic obesity; systemic fat utilization

Quantified reduction

—

Significant HFD fat gain ↓Lee 2015

Murine models, dose-dependent (5 & 15 mg/kg).

IGF-1 impact

—

No direct IGF-1 pathway; AMPK-mediated

Effect on lean mass

—

High dose significantly ↑ lean mass in mice

Insulin sensitivity

—

Reversed HFD insulin resistance in 7 days (mice)Lee 2015

Triglycerides

—

AMPK-driven FA oxidation suggests TG benefit (not directly measured)

Glucose metabolism

—

Improved glucose tolerance; GLUT4 upregulationLee 2015

Effect reversibility

—

Unknown — no long-term follow-up data

Context dependency

—

No effect in normal-chow mice; requires metabolic stressReynolds 2021

Key publication

—

Lee Cell Metab 2015 · Reynolds Nat Commun 2021 · Kim Cell Metab 2018Lee 2015 Reynolds 2021 Kim 2018

04Side Effects & Safety

Parameter

GHRP-6

MOTS-c

Hunger

Pronounced — defining feature vs ipamorelin

—

Cortisol elevation

Mild

—

Prolactin elevation

Mild

—

Injection site reaction

Mild

Mild irritation (reported)

Cancer risk

Contraindicated in active malignancy

Contradictory data — some models suggest pro-proliferative effects

Pregnancy / OB

Avoid

Avoid — insufficient safety data

Fluid retention / Edema

—

Not reported

Glucose intolerance

—

Improves glucose toleranceLee 2015

Cardiovascular

—

Heart palpitations (anecdotal); cardiac hypertrophy reversed in diabetic rats

CNS / Neurological

—

Insomnia, headache (anecdotal reports)

GI symptoms

—

Nausea, stomach discomfort (reported)

Antibody formation

—

No data (no long-term human trials)

Evidence quality

—

Phase 1 analog (CB4211); preclinical; anecdotal humanA first-in-human phase 1 study 2021

Absolute Contraindications

GHRP-6

·Active malignancy
·Pregnancy / breastfeeding

MOTS-c

·Pregnancy / breastfeeding (insufficient data)

Relative Contraindications

GHRP-6

·Severe insulin resistance (appetite-driven caloric load)

MOTS-c

·Active cancer or cancer predisposition
·AMPK pathway deficiency (efficacy nullified)
·Use with cancer-promoting medications (theoretical)

05Administration Protocol

Parameter

GHRP-6

MOTS-c

1. Reconstitution

Add 2 mL bacteriostatic water to 5 mg vial → 2.5 mg/mL.

Add 1–2 mL bacteriostatic water. At 10 mg/vial, 1 mL gives 10 mg/mL concentration. Roll gently to dissolve.

2. Injection site

SQ — abdomen. Rotate sites.

Subcutaneous — abdomen, thigh, or deltoid. Rotate sites to avoid lipohypertrophy. Pinch fat layer.

3. Timing

Pre-meal for appetite support; pre-sleep for GH alignment.

Pre-workout or fasted state preferred — metabolic context amplifies AMPK response. 2–3× per week.

4. Storage

Lyophilised: room temp. Reconstituted: refrigerate ≤30 days.

Lyophilised: room temp, protected from light. Reconstituted: refrigerate, use within 21–30 days. Short systemic stability.

5. Needle

29–31G, 4–8 mm insulin syringe.

27–31G insulin syringe. Short needle (4–6 mm) for SQ delivery. Clean technique mandatory.

06Stack Synergy

GHRP-6

— no documented stacks

MOTS-c

+ Ipamorelin

Moderate

View Ipamorelin →

MOTS-c activates AMPK/PGC-1α for mitochondrial efficiency and fatty acid oxidation; ipamorelin stimulates GH for anabolic recovery and sleep depth. Pathways are complementary — MOTS-c handles metabolic flexibility and glucose handling while ipamorelin drives recovery and body recomposition through GH. Theoretical synergy is high; clinical data is lacking.

MOTS-c: 5 mg SQ · pre-workout (2–3×/wk)
Ipamorelin: 200–300 mcg SQ · pre-sleep (daily)
Primary benefit: Metabolic flexibility + GH recovery + ROS reduction