MK-677 (Ibutamoren) vs HGH Fragment 176-191
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
MK-677 (Ibutamoren)
MK-677, also known as Ibutamoren, is an orally active growth hormone secretagogue. Unlike peptides, it can be taken orally and has a long half-life, providing 24-hour GH elevation.
Full details →HGH Fragment 176-191
HGH Fragment 176-191 is the fat-reducing portion of the growth hormone molecule. Unlike AOD-9604 (which has an additional tyrosine), this is the exact fragment of HGH responsible for lipolytic effects.
Full details →Side-by-Side Comparison
| Aspect | MK-677 (Ibutamoren) | HGH Fragment 176-191 |
|---|---|---|
| Mechanism | Acts as a potent, selective agonist of the ghrelin receptor (GHS-R1a). Increases GH and IGF-1 levels without affecting cortisol. Mimics ghrelin's GH-releasing effects. | Mimics the lipolytic region of growth hormone, stimulating fat breakdown and inhibiting lipogenesis without affecting blood sugar or promoting growth. Works independently of GH receptors. |
| Typical Dosage | Typical dosing: 10-25mg taken orally once daily. Often taken at night due to sleep benefits and appetite increase. | Typical dosing: 250-500mcg daily, often split into 2-3 doses. Usually administered on empty stomach, often with fasted cardio. |
| Administration | Oral administration (capsule or liquid). Can be taken with or without food. Long half-life allows once-daily dosing. | Subcutaneous injection. Best results when used fasted and combined with exercise. Avoid eating for 30 minutes post-injection. |
| Side Effects | Increased appetite and water retention are most common. May cause lethargy, vivid dreams, and mild numbness. Can affect blood glucose and insulin sensitivity. | Generally well-tolerated. May cause injection site irritation, temporary lethargy, or headache. Does not affect blood glucose significantly. |
| Best For |
What They Have in Common
Both MK-677 (Ibutamoren) and HGH Fragment 176-191 are commonly used for: