Dosing Protocols for Peptides in Bodybuilding

Where these protocols come from

No regulator has approved any peptide on this page for building muscle or speeding recovery, so none has a label dose for that use. As of October 2026, most are sold as "research use only" chemicals, and WADA prohibits all of them for tested athletes. Our overview of what "research use only" means legally covers that side.

The numbers lifters use come mostly from vendor guides and forum write-ups. A few trace back to small human studies in healthy adults. Each figure below says where it comes from, and none of it is a recommendation.

GH secretagogues: the two-peptide stack

The most common bodybuilding protocol pairs two kinds of growth hormone (GH) secretagogue. One is a GHRH analog, usually Mod GRF 1-29, which vendors often sell as "CJC-1295 without DAC." The other is a GHRP. Ipamorelin is the most popular; GHRP-2 and GHRP-6 are older options.

The basic idea has human data behind it. In a 1990 study of 18 healthy men, low IV doses of GHRP-6 given with GHRH released more GH than the two would add up to separately. As of October 2026, though, we found no controlled human trial of the Mod GRF plus ipamorelin combination that users run.

The "saturation dose" rule

Forum guides often say GHRPs max out at about 1 mcg/kg, or roughly 100 mcg per injection, and that more only adds side effects. We couldn't trace that rule to a study showing a plateau. In the 1990 study, peak GH kept rising across the doses tested, from 0.1 to 1.0 mcg/kg IV. It was about four times higher at the top dose than at 0.3 mcg/kg. Nobody got more than 1 mcg/kg, so the study can't locate a ceiling.

Prolactin and cortisol did roughly double at 1 mcg/kg, which fits the side-effect half of the rule. All of this was IV GHRP-6, not the subcutaneous injections lifters use. The site's peptide entries list wider ranges from vendor and community guidance: 100-300 mcg per injection for GHRP-2 and GHRP-6, and 200-300 mcg per dose for ipamorelin.

Timing and food

Users commonly describe injecting on an empty stomach, with the main dose at bedtime. The rationale is that the largest natural GH pulse comes early in sleep, and raised blood glucose suppresses GH release. Ipamorelin users often avoid food for about 30 minutes before and after a dose. Some GHRP-6 guides call for 2-3 hours of fasting beforehand. No study has tested these timings for these peptides.

Reported side effects differ by compound. Users know GHRP-6 for intense hunger soon after injection, which some lifters welcome while bulking and avoid while cutting. In human studies, GHRP-2 raised appetite along with cortisol and prolactin. Ipamorelin users most often mention temporary water retention and tingling hands. Our page on peptide health risks has more.

CJC-1295 with DAC and the "GH bleed" claim

Many forum guides, including an earlier version of this page, say CJC-1295 with DAC causes a constant "GH bleed" that flattens natural pulses. The human data say otherwise. In a 2006 study, healthy men aged 20-40 received one injection of 60 or 90 mcg/kg. A week later, their GH pulses were unchanged in frequency and size. The baseline between pulses rose about 7.5-fold, lifting mean GH by 46% and IGF-1 by 45%.

A companion 2006 trial in healthy adults measured a half-life of 5.8-8.1 days, with GH raised 2- to 10-fold for at least six days after one injection. Doses of 30-60 mcg/kg were the best tolerated, which for most adults is more than the vendor weekly range. We couldn't find where that vendor range comes from. Neither trial shows what months of repeated use do. As of October 2026, FDA's list of risky bulk substances links CJC-1295 to serious adverse events. These include raised heart rate and a whole-body vasodilatory reaction.

Recovery peptides: BPC-157 and TB-500

BPC-157

Users commonly report 250-500 mcg a day by subcutaneous injection, sometimes split into morning and evening doses. The 4-12 week duration most people describe comes from vendor and community guides. Some users with injuries describe 1-2 mg a day. No human dose-finding study exists for any of these amounts.

The human evidence is thin. A 2025 systematic review found 36 relevant studies: 35 preclinical and one small retrospective clinical series, with no clinical safety data. A 2025 pilot gave two adults 10 mg and then 20 mg by IV infusion, with no reported side effects. As of October 2026, no controlled human trial has published results. A sham-controlled Phase 1 at the University of Arkansas plans 90 days of daily subcutaneous injections after rotator cuff surgery, starting in January 2027.

Many users inject near the injured area, though no human trial has compared injection sites. Most animal studies gave BPC-157 systemically and still reported effects in tendon and muscle. Some users take oral forms for gut problems, based on rodent data and the peptide's reported stability in stomach acid. We found no human study showing a gut benefit.

TB-500

TB-500 isn't the same thing as thymosin beta-4. Anti-doping chemists identified it as a seven-amino-acid fragment (Ac-LKKTETQ) of the 43-amino-acid protein. Trials of the full protein don't carry over to the fragment. As of October 2026, FDA says it has found no human exposure data for the fragment. Many users aren't sure which one their vial holds.

Vendor guidance describes 2-2.5 mg twice a week for 4-6 weeks, then monthly maintenance doses. Forum users describe a wider spread: 2-5 mg twice weekly, or 0.5-2 mg daily or every other day. Guides often say the injection site doesn't matter because TB-500 acts "systemically," but no human absorption data exist either way.

Downstream compounds: IGF-1 LR3 and PEG-MGF

IGF-1 LR3

No human dose of IGF-1 LR3 has been tested. Vendor and community guides list 40-80 mcg a day; forum users more often describe 20-50 mcg, with some at 80-100 mcg. Cycles usually run 4-6 weeks. Users commonly inject it after training. Some use subcutaneous injection, while others inject into the muscle just worked.

Hypoglycemia is the risk users mention most. Many describe eating 30-50 g of carbohydrate within about 30 minutes of injecting to head it off. That's community practice, not a tested protocol.

The often-quoted 20-30 hour half-life has no measured source. In a 1993 rat study, LR3 left the blood about ten times faster than native IGF-1 (9.8 versus 0.9 mL/min per kg).

PEG-MGF

Mechano growth factor (MGF) is a splice variant of the IGF-1 gene. In a 2003 rat study, muscle made a short burst of it within days of local damage. PEG-MGF is a pegylated version sold on the claim that it lasts longer. Users describe 100-200 mcg injected into the muscle just trained, often split between sides. As of October 2026, FDA says it has found no human exposure data for PEG-MGF, and WADA lists MGFs under S2.3.

Cycling

The usual community pattern for GH secretagogues is 8-12 weeks on, then at least 4 weeks off, so the pituitary can recover. The site's peptide entries list 8-12 weeks for ipamorelin and GHRP-6, and 8-16 weeks for GHRP-2.

The human data on tolerance are limited. In a 1998 study, 12 healthy older adults injected hexarelin, another GHRP, twice daily for 16 weeks. Their GH response fell by about 45%, then returned to baseline within four weeks of stopping. In contrast, daily oral MK-677 kept GH and IGF-1 at young-adult levels in a two-year trial of older adults. Desensitization may depend on the compound, and nobody has measured it for ipamorelin.

Recovery peptides are usually run in shorter blocks tied to a specific injury. That pattern also comes from vendor guidance rather than trials.

What we still don't know

No trial has measured muscle or fat outcomes for any of these protocols in lifters. A 2018 review of GH secretagogues found few long-term controlled studies and flagged rising blood glucose from reduced insulin sensitivity. Product quality adds another unknown, since a vial's contents may not match its label. Our guide to peptide sourcing and quality control covers what buyers check, and the page on long-term effects in bodybuilding looks at multi-year use.