Side-by-side · Research reference

HGH Fragment 176-191vsSS-31

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

AAnimal-StrongHUMAN-REVIEWED28/59 cited

BPhase 3HUMAN-REVIEWED9/43 cited

HGH Fragment 176-191

GH Fragment · Pre-Clinical

50%Weight gain reductionNg 2000

~26 minHalf-life (est.)

No IGF-1 ↑GH axis impact

SQ · IP (animal) · Oral (tested)

SS-31

Cardiolipin-binding · Mitochondrial protective

40 mgDaily doseSzeto 2014

Phase 3Evidence levelSzilagyi 2009 Szeto 2014

~3 hrHalf-life

SQ · Abdomen · Once daily

01Mechanism of Action

Parameter

HGH Fragment 176-191

SS-31

Primary target

Beta-3 adrenergic receptors on adipocytesHeffernan 2001

Cardiolipin in inner mitochondrial membraneSzeto 2014

Pathway

Fragment → β3-AR upregulation → Enhanced lipolytic sensitivityHeffernan 2001

Cardiolipin binding → cristae stabilisation → ETC integrity → reduced ROS + preserved ATP synthesisSzeto 2014 Szilagyi 2009

Downstream effect

Increased lipolysis and beta-3 AR mRNA expression without IGF-1 axis activation

Mitochondrial bioenergetic preservation; cardio-, neuro-, and reno-protective effects in animal + clinical studiesSzeto 2014

Feedback intact?

N/A — does not interact with GH/IGF-1 axis

—

Origin

Synthetic peptide derived from hGH residues 176-191; AOD9604 includes N-terminal tyrosine (177-191)Cox 2015

Synthetic tetrapeptide D-Arg-Dmt-Lys-Phe-NH₂; cell-permeable, mitochondrial-selectiveSzeto 2014

Antibody development

Not reported in available studies

—

02Dosage Protocols

Parameter

HGH Fragment 176-191

SS-31

Animal dose (oral)

500 mcg/kg body weightNg 2000

Obese Zucker rats, 19 days.

—

Animal dose (IP)

Not specified (14-day chronic administration)Heffernan 2001

Obese mice, daily IP injection.

—

Human equivalent dose

Not established — no published human RCTs

—

Frequency

Once daily (animal models)

Once daily

Evidence basis

Animal studies only

Multiple Phase 3 trials (Barth, AMD, ischemia-reperfusion)Szeto 2014 Szilagyi 2009

Duration tested

14–19 daysHeffernan 2001 Ng 2000

—

Detection window

50 pg/mL LOD in urine; stable metabolite extends detectionCox 2015

WADA-banned; anti-doping testing available.

—

Oral bioavailability

Demonstrated efficacy in animal oral administrationNg 2000

Potential for oral therapeutic development.

—

Standard dose

—

40 mg / day SQ (clinical trials)Szeto 2014

Anecdotal community range 5-10 mg/day. Phase 3 trials use 40 mg.

Lower / starter dose

—

5 mg / day (anecdotal)

Duration

—

Indefinite for mitochondrial disease; cycled for healthspan use

Reconstitution

—

Bacteriostatic water

Timing

—

Morning fasted preferred; pre-workout for exercise-induced mitochondrial stress

Half-life

—

~3 h plasma; tissue uptake longer

03Metabolic / Fat Loss Evidence

Parameter

HGH Fragment 176-191

SS-31

Primary fat target

Adipose tissue (general) — beta-3 AR mediated lipolysisHeffernan 2001

—

Weight gain reduction

50% reduction vs control (15.8 ± 0.6 g vs 35.6 ± 0.8 g)Ng 2000

Obese Zucker rats, 19 days oral administration.

—

Body fat reduction

Significant decrease in body weight and body fat in obese mice (14 days)Heffernan 2001

—

Lipolytic activity

Increased adipose tissue lipolytic activityNg 2000

Direct measurement in treated animals.

—

Beta-3 AR expression

Upregulated β3-AR mRNA in obese mice to lean-comparable levelsHeffernan 2001

—

Insulin sensitivity

No adverse effect — euglycemic clamp confirmedNg 2000

Contrasts with intact hGH diabetogenic effects.

—

IGF-1 impact

No elevation — fragment does not activate GH/IGF-1 axis

—

Beta-3 AR dependency

Effect abolished in β3-AR knockout miceHeffernan 2001

Confirms β3-AR as primary mechanism.

—

Route of administration

Efficacy demonstrated via oral and IP routesNg 2000 Heffernan 2001

—

Human evidence

None published — pre-clinical only

—

04Side Effects & Safety

Parameter

HGH Fragment 176-191

SS-31

Insulin sensitivity

No adverse effects observed in euglycemic clamp (animal)Ng 2000

—

GH/IGF-1 axis

No activation — avoids diabetogenic effects of full GHNg 2000

—

Human safety data

Not available — no published human trials

—

WADA status

Banned as performance-enhancing drugCox 2015

—

Metabolic profile

Six metabolites identified; CRSVEGSCG most stableCox 2015

Detection window implications for doping control.

—

Injection site reaction

—

Erythema, mild pruritus

GI symptoms

—

Nausea (uncommon)

Headache

—

Reported in some Phase 3 trials

Cardiovascular

—

Cardio-protective in studies; no signal of harm

Long-term safety

—

Phase 3 data over 24+ months; no major safety signalsSzeto 2014

Pregnancy / OB

—

Avoid — insufficient data

Absolute Contraindications

HGH Fragment 176-191

·Competitive athletes (WADA-banned)Cox 2015

SS-31

·Pregnancy / breastfeeding
·Hypersensitivity to peptide

Relative Contraindications

HGH Fragment 176-191

·Absence of human safety data — experimental use only

SS-31

·None established

05Administration Protocol

Parameter

HGH Fragment 176-191

SS-31

1. Route

Subcutaneous injection primary route in research context. Oral administration demonstrated efficacy in animal models at 500 mcg/kg.

Add bacteriostatic water per label. Light-protected handling.

2. Frequency

Once daily dosing used in animal studies. Timing not specified; GH-independent mechanism suggests flexibility.

SQ — abdomen or thigh. Rotate sites.

3. Duration

Animal protocols: 14–19 days. Human duration not established — no published trials.

Morning fasted; pre-workout for exercise-augmented mitochondrial stress.

4. Storage

Lyophilized peptide storage per standard peptide protocols. Metabolite stability suggests refrigerated reconstituted solution viable.

Lyophilised: refrigerate, light-protected. Reconstituted: refrigerate ≤30 days.

5. Detection

Detectable in urine via SPE-LC-MS at 50 pg/mL LOD. Extended detection window via stable metabolite CRSVEGSCG.Cox 2015

29–31G, 4–8 mm insulin syringe.

06Stack Synergy

HGH Fragment 176-191

— no documented stacks

SS-31

+ MOTS-c

Moderate

View MOTS-c →

SS-31 and MOTS-c address mitochondrial decline through complementary axes. SS-31 protects existing mitochondrial structure (cardiolipin binding, cristae stabilisation). MOTS-c upregulates AMPK/PGC-1α, triggering biogenesis of new mitochondria. Together they pair preservation with renewal — anecdotally favoured in healthspan and post-cardio-event recovery protocols.

SS-31: 5–10 mg SQ · daily morning
MOTS-c: 5 mg SQ · 2× per week pre-workout
Primary benefit: Mitochondrial preservation + biogenesis