Disclaimer: This guide is educational content intended for research and informational purposes only. Ghrelin is investigational, not FDA or EMA-approved for therapeutic use. Consult a qualified healthcare provider before use. This is not medical advice.
Ghrelin is a 28-amino acid peptide hormone produced by the gastrointestinal tract, commonly referred to as the "hunger hormone." It binds to the growth hormone secretagogue receptor 1a (GHSR-1a), a G-protein coupled receptor in the hypothalamus, pituitary, and peripheral tissues. This binding stimulates appetite through neuropeptide Y and AgRP neurons, potently triggers growth hormone release, and modulates insulin secretion, gastric motility, energy homeostasis, and inflammatory responses.
As a peptide, ghrelin is administered via injection and remains investigational with limited long-term safety data. Its primary practical applications center on appetite stimulation for cachexia, anorexia, gastroparesis, and post-surgical recovery rather than direct fat loss or muscle gain. Understanding realistic expectations, proper dosing, and cycling protocols is essential for safe and effective use.
Recommended dose range: 1–3 mcg/kg body weight, administered once to twice daily via subcutaneous or intramuscular injection.
For a 180 lb (82 kg) individual:
- Low end: 82 mcg per injection (1 mcg/kg)
- Mid range: 164–246 mcg per injection (2–3 mcg/kg)
- Frequency: Once daily or split into two daily doses
Typical starting approach:
- Week 1–2: 1 mcg/kg once daily to assess tolerance
- Week 3–4: 1.5–2 mcg/kg once daily or split into two daily doses
- Week 5+: Titrate to 2–3 mcg/kg based on response and side effects
Standard protocols typically run 6–12 weeks with structured rest periods:
- Short cycle: 6–8 weeks on, 2–4 weeks off
- Standard cycle: 8–10 weeks on, 4–6 weeks off
- Extended cycle: 10–12 weeks on, 6–8 weeks off
The off-period allows endogenous hormone production to stabilize and prevents receptor downregulation or desensitization.
Ghrelin is typically supplied as lyophilized powder requiring reconstitution:
- Calculate total dose needed for your cycle (weekly dose × number of weeks)
- Use bacteriostatic water or saline as the reconstitution medium (typical concentration: 1 mL per 100 mcg or per manufacturer guidelines)
- Draw the specified volume of bacteriostatic water into a sterile syringe
- Inject slowly into the vial, allowing the powder to dissolve gradually—avoid vigorous shaking
- Allow 5–10 minutes for complete dissolution; the solution should be clear to slightly cloudy
- Store reconstituted solution at 2–8°C (refrigerate) in an airtight container; typical stability is 14–30 days depending on the medium
- Unopened vials: Store at 2–8°C or at room temperature per manufacturer guidance
- Reconstituted solution: 2–8°C in a dark container; discard after 30 days
- Prepared doses in syringes: Pre-drawn syringes are generally stable for 24–48 hours refrigerated; avoid freezing reconstituted peptide
Cycle length: 8–12 weeks on, 4–6 weeks off
Dosing:
- Weeks 1–2: 1.5 mcg/kg once daily
- Weeks 3–12: 2–3 mcg/kg once to twice daily (morning and/or evening before meals)
Timing: Administer 30–60 minutes before intended meals to maximize appetite drive during eating windows.
Expected outcome: Increased hunger and food intake beginning within 30–60 minutes; transient flushing and warmth sensations are normal and diminish with repeated dosing.
Adjustment markers:
- If appetite increase is insufficient by week 3, increase to twice-daily dosing or raise to 3 mcg/kg
- If gastrointestinal discomfort emerges, reduce to once daily or lower dose
- Monitor cortisol and prolactin elevations if available; these are typically transient
Cycle length: 6–10 weeks on, 4–6 weeks off
Dosing:
- Weeks 1–2: 1 mcg/kg once daily (evening preferred to align with natural GH secretion)
- Weeks 3–10: 1.5–2.5 mcg/kg once daily, typically in the evening or pre-bedtime
Timing: Administer in the evening or 60–90 minutes before sleep to leverage circadian GH release patterns.
Expected outcome: Enhanced pituitary GH secretion independent of GHRH; modest appetite increase; potential benefits for post-surgical healing and tissue recovery.
Adjustment markers:
- GH dynamics may take 2–3 weeks to stabilize; avoid frequent dose changes during initial weeks
- If transient hypoglycemia or blood glucose fluctuations occur (monitor fasting glucose), reduce dose by 0.5 mcg/kg
- Elevated cortisol or prolactin: If marked, reduce frequency to every other day and reassess after 1 week
Cycle length: 8–12 weeks on, 6–8 weeks off
Dosing:
- Weeks 1–2: 1.5 mcg/kg once to twice daily
- Weeks 3–12: 2–3 mcg/kg once to twice daily (morning and evening)
Timing: Administer twice daily (AM and PM) to maintain consistent receptor activation and growth factor signaling.
Expected outcome: Enhanced wound healing, improved gastric ulcer recovery (from mechanistic studies), and accelerated colonic anastomosis repair (animal models); appetite increase is secondary.
Adjustment markers:
- Healing progress may require 4–6 weeks to become evident; maintain consistent dosing
- If nausea or GI discomfort persists beyond week 2, reduce to once daily or lower dose per kg
- Monitor wound progression objectively (imaging, clinical assessment) every 3–4 weeks
Cycle length: 10–12 weeks on, 6–8 weeks off
Dosing:
- Weeks 1–2: 1 mcg/kg once daily
- Weeks 3–12: 1.5–2 mcg/kg once to twice daily
Timing: Consistent twice-daily dosing (morning and evening) to maintain peripheral GHSR signaling in joint and systemic tissues.
Expected outcome: Mechanistic evidence supports reduced inflammatory cytokine expression (IL-1β, MMP-3, MMP-13) and cartilage protection; human clinical efficacy remains unproven.
Adjustment markers:
- Inflammatory markers (CRP, IL-6) should be monitored at baseline, week 6, and week 12
- Joint symptoms may improve modestly after 6–8 weeks; assess pain, mobility, and swelling subjectively and objectively
- If side effects emerge, reduce to once daily; anti-inflammatory effects may persist with lower dosing
- Prepare supplies: Sterile syringe (0.5–1 mL), sterile needle (27–31 gauge), alcohol swab, reconstituted ghrelin in refrigerated vial
- Select injection site: Abdomen (around navel), thigh, or upper arm; rotate sites daily to prevent irritation or lipohypertrophy
- Clean the site: Swab with alcohol; allow 10–15 seconds to air dry
- Draw dose: Insert needle into vial, pull back plunger to draw the calculated volume (e.g., 164 mcg for an 82 kg person at 2 mcg/kg)
- Inject: Pinch skin to form a fold; insert needle at a 45–90° angle approximately 0.5 inches into subcutaneous tissue; inject slowly over 5–10 seconds
- Withdraw: Remove needle; apply gentle pressure with alcohol swab if bleeding occurs
- Dispose: Place needle and syringe in a sharps container
Follow steps 1–5 above, but insert needle into the deltoid, vastus lateralis, or gluteus maximus at a 90° angle, penetrating muscle tissue (approximately 1–1.5 inches depth). Inject over 10 seconds. IM injection may produce slightly faster absorption but carries higher infection risk if sterile technique is not maintained.
- For appetite stimulation: Inject 30–60 minutes before intended meals
- For GH stimulation: Inject in the evening, 60–90 minutes before sleep
- For recovery: Inject twice daily (morning and evening), independent of meal timing
- Avoid: Injecting immediately before or after intense exercise; the acute metabolic state may interfere with peptide absorption
| Week | Dose (mcg/kg) | Frequency | Total Daily Dose* | Notes |
|---|
| 1–2 | 1.5 | Once | 123 mcg | Assess tolerance; monitor hunger and GI effects |
| 3–4 | 2 | Once | 164 mcg | Increase frequency if appetite insufficient |
| 5–6 | 2 | Twice | 328 mcg | Full dosing; monitor for side effects |
| 7–8 | 2.5 | Twice | 410 mcg | Peak dosing; consistent appetite elevation expected |
| 9–10 | 2.5 | Twice | 410 mcg | Maintain; begin planning 4-week off-cycle |
| — | 0 | Off | 0 mcg | 4-week rest; allow receptor sensitivity reset |
*Based on 82 kg individual; adjust proportionally for different body weights.
- Weeks 1–2 (titration): Mild hunger increase; possible transient flushing; assess side effect tolerance
- Weeks 3–4 (escalation): Pronounced hunger onset; increased food intake within 30–60 min of injection; mild nausea possible at higher doses
- Weeks 5–8 (peak): Consistent appetite elevation; stable GH stimulation if measured; transient hypoglycemia or cortisol elevation likely mild and transient
- Weeks 9–10 (maintenance): Effects plateau; consider dose adjustment if appetite blunting emerges (receptor desensitization)
- Off-cycle (weeks 11–14): Gradual return to baseline appetite; endogenous ghrelin and GH secretion normalize
Acute Effects (30 minutes – 2 hours post-injection)
- Hunger sensation: Pronounced within 30–60 minutes; often described as a true "gnawing" appetite
- Flushing & warmth: Mild to moderate at the injection site or systemic; typically resolves within 1–2 hours
- Transient GI symptoms: Nausea or mild discomfort, particularly at doses >3 mcg/kg or on an empty stomach
- Increased food intake: Ad libitum eating increases 15–40% depending on baseline appetite and dose
- Body weight gain: 0.5–2 lbs per week if caloric surplus is maintained; primarily as fat mass and food-derived weight
- Growth hormone elevation: Modest if measured; typically peaks 30–60 minutes post-injection
- Tolerance development: Acute flushing and nausea often diminish by week 2–3 with consistent dosing
- Stable appetite elevation: Hunger becomes predictable; food intake remains elevated if dietary intake is not actively controlled
- Body composition changes: Continued slow weight gain if caloric surplus is maintained; no muscle-building effects observed independent of increased food intake and training stimulus
- Potential receptor desensitization: Some individuals report diminished hunger sensation by week 6–8; dose escalation or cycling off may be necessary
- Endocrine markers: Transient elevations in cortisol and prolactin generally mild and normalize despite continued dosing
- Maintained appetite stimulation: Less pronounced than early weeks but sufficient for continued increased intake if desired
- Possible appetite plateau: Some individuals report blunted response by week 10–12; this suggests receptor adaptation and justifies the off-cycle
- GH & metabolic effects: Limited clinical data; growth hormone elevation may diminish with chronic dosing
- No proven fat loss or muscle gain: Weight gain occurs only if food intake exceeds expenditure; ghrelin supplementation does not inherently drive fat loss or anabolism
Post-Cycle (Off-Cycle Weeks 1–8)
- Gradual appetite normalization: Hunger returns toward baseline over 1–3 weeks
- Endogenous ghrelin recovery: Natural ghrelin secretion re-establishes; paradoxically may increase slightly above baseline initially due to compensatory upregulation
- Weight stabilization: If training stimulus and protein intake are maintained, lean mass may stabilize; fat gain from the on-cycle may persist unless caloric deficit is imposed
Mistake 1: Dosing Without Body Weight Adjustment
Error: Using a fixed dose (e.g., 200 mcg) regardless of individual body weight.
Impact: Lighter individuals become over-dosed (elevated side effects); heavier individuals are under-dosed (inadequate appetite response).
Solution: Always calculate dose as mcg/kg body weight. For an 82 kg person, 2 mcg/kg = 164 mcg. For a 60 kg person, 2 mcg/kg = 120 mcg.
Error: Administering ghrelin and expecting automatic fat loss or lean mass gain.
Impact: Weight gain occurs (from increased food intake), but body composition is primarily fat; no anabolic or lipolytic effects occur independent of training and diet.
Solution: Use ghrelin specifically for appetite stimulation when weight gain is the goal (cachexia, recovery). If fat loss is desired, pair with a caloric deficit and resistance training—ghrelin is contraindicated for fat loss protocols.
Error: Administering ghrelin within 60 minutes before or immediately after training.
Impact: The acute metabolic state post-exercise may interfere with peptide absorption; acute ghrelin suppression from exercise may blunt peptide effects.
Solution: Inject ghrelin 90–120 minutes before training (it will have cleared absorption window by workout start) or 2+ hours post-training.
Error: Dosing continuously for 16+ weeks without a planned rest period.
Impact: Receptor downregulation and desensitization; diminished appetite response by week 8–10; potential metabolic dysregulation from prolonged GH axis stimulation.
Solution: Follow a structured 8–12 weeks on, 4–6 weeks off schedule. The off-cycle allows GHSR-1a sensitivity to reset and endogenous ghrelin production to normalize.
Error: Repeatedly injecting into the same site; using non-sterile technique.
Impact: Lipohypertrophy (fatty tissue buildup); infection risk; inconsistent absorption kinetics; injection site pain.
Solution: Rotate injection sites daily (abdomen, thighs, arms). Use sterile technique: clean with alcohol, allow air-dry, use fresh needle for each injection. Vary sites within each body region to prevent localized lipohypertrophy.