GHRP-2

GHRP-2 is usually described as the stronger GH releaser, but it's less selective: in human studies it slightly raised prolactin and cortisol, and it increases hunger. In the animal studies that introduced ipamorelin, it released GH without raising cortisol, and users report less effect on appetite. That's why users sensitive to side effects often pick ipamorelin. We found no head-to-head human trial.

Community guides advise it because food, and the insulin rise that follows, is thought to blunt the GH pulse. The Japanese diagnostic label also calls for fasting. We found no study comparing fed and fasted GHRP-2 injections, so the 30-minute and 2-hour windows are community conventions, not tested rules.

Hunger is the most consistent effect users describe, and a 2005 study backs it up: seven healthy men infused with GHRP-2 ate about 36% more at a buffet meal than on saline. The hunger is a direct result of GHRP-2 mimicking ghrelin, the body's primary hunger hormone. For some, this is a benefit for bulking, but for others, it's a difficult side effect. Users say it peaks 20-30 minutes after injection and plan a meal for then; no study has measured that timing.

They act on different signals: GHRP-2 on the ghrelin receptor, CJC-1295 as a GHRH analog. In human infusion studies, GHRH and GHRP-2 given together released more GH than either alone. No trial has tested the CJC-1295 combination itself, and a bigger GH pulse hasn't been shown to improve muscle or fat outcomes.

We found no evidence that it does. As a secretagogue, it prompts your own pituitary gland to release GH rather than supplying GH from outside. Desensitization is the open question. GHRP-2 hasn't been tested over months, but with the related peptide hexarelin, the GH response partly faded over 16 weeks in older adults and recovered 4 weeks after stopping. Users cycle GHRP-2 for this reason; cycle lengths come from community practice.