HGH Fragment 176-191 vs MK-677
Moderate Research vs Well Studied
monitor Mechanism-based · 47% Both HGH Fragment 176-191 and MK-677 affect insulin sensitivity or blood glucose. Monitor fasting glucose and HbA1c. Consider adding an insulin sensitizer (metformin/berberine).
Molecular Data
HGH Fragment 176-191 MK-677
Weight 1,817.1 Da 624.77 Da
Half-life 15-20 minutes ~24 hours
Chain 16 amino acids —
Type hGH C-terminal fragment (176-191) Non-peptide ghrelin receptor agonist
Key Benefits
HGH Fragment 176-191
01 Stimulates lipolysis without growth hormone side effects
02 Does not affect blood glucose or insulin sensitivity
03 Does not increase IGF-1 levels
04 Selectively targets fat metabolism
05 No impact on bone or organ growth
MK-677
01 97% increase in 24-hour growth hormone secretion
02 40-72% elevation in IGF-1 levels
03 Enhanced sleep quality with improved REM patterns
04 Preferential lean tissue gains of 1.1-2.7kg over 8-12 months
05 15% basal metabolic rate increase within 2 weeks
06 Oral administration (no injections required)
Dosing Protocols
HGH Fragment 176-191
250-500mcg / Twice daily (fasted)
Fat loss - Standard 250mcg Twice daily (morning fasted + pre-bed)
Enhanced fat loss 500mcg Twice daily (morning fasted + pre-bed)
Conservative start 250mcg Once daily (morning, fasted)
MK-677
Start 12.5mg daily, increase to 25mg based on tolerance / Once daily, preferably at bedtime on empty stomach
Side Effects
HGH Fragment 176-191
Injection site irritation (redness, mild swelling)
Headache, particularly in the first few days
Generally well-tolerated with a favorable safety profile
MK-677
Appetite stimulation (>50% of users)
Water retention (30-40%)
Lethargy (20-30%)
Fasting glucose elevation (5-15mg/dL)
Note on testosterone suppression: at doses up to 20 mg daily, MK-677 is unlikely to cause significant testosterone suppression on its own. Above 20 mg daily, the likelihood of suppression and other side effects (insulin resistance, water retention, lethargy) increases. The case report documenting 85.7% testosterone suppression involved co-administration with LGD-4033, a SARM known to be profoundly suppressive, making the SARM the likely primary driver of that suppression.
Contraindications
Pregnancy or breastfeeding
Active cancer or history of malignancy
WADA prohibited - athletes subject to testing must avoid
Heart disease or congestive heart failure
Diabetes or pre-diabetes
Active cancer
Severe cardiovascular disease
Pregnancy or breastfeeding
Research Evidence
HGH Fragment 176-191 MK-677
Status Moderate Research Well Studied
References 4 studies 7 studies
Latest 2014 July 2024
FDA Approved No No
This comparison is for educational and research purposes only. Consult a healthcare professional before use.