MK-677, also known as Ibutamoren or Nutrobal, is a growth hormone secretagogue. It works by mimicking the action of the hormone ghrelin to stimulate the release of growth hormone from the pituitary gland. MK-677 has gained popularity among bodybuilders and athletes for its ability to increase growth hormone and IGF-1 levels, potentially leading to increased muscle mass and strength.
However, there has been some concern that MK-677 may lower natural testosterone production. Here is a comprehensive look at the evidence surrounding MK-677 and testosterone levels:
- Several studies have specifically measured testosterone levels in humans and animals receiving MK-677 treatment. The findings have been mixed:
- A study in older adults found that 25 mg/day of MK-677 for 6 months had no effect on total or free testosterone levels
- Similarly, a study in growth hormone deficient adults found no change in testosterone levels with 1 year of MK-677 treatment
- However, a study in rats noted that very high doses of MK-677 (10 times the standard human dose) lowered testosterone after 4 weeks
- There are several mechanisms by which MK-677 could potentially affect testosterone levels:
- By increasing growth hormone and IGF-1 levels, MK-677 may cause negative feedback to suppress natural growth hormone and testosterone production
- MK-677 may also decrease gonadotropins like luteinizing hormone, which signals the testes to produce testosterone
- The rat study suggesting MK-677 lowers testosterone found effects only at extremely high doses, indicating testosterone suppression may require supraphysiological dosing
- Human clinical evidence suggests MK-677 does not significantly impact testosterone at doses recommended for performance enhancement and muscle building (typically around 25 mg/day)
- However, there may be modest short-term testosterone suppression at extremely high MK-677 doses
In summary, the preponderance of evidence suggests MK-677 does not lower testosterone levels to a meaningful extent, especially at commonly used doses. However, long-term studies are limited and more research is needed. Those using MK-677 may still consider having testosterone levels monitored periodically to detect any unexpected declines.
Vitality Hormone Clinic in specializes in
hormone optimization and anti-aging treatments personalized to your unique health needs. Our experiential physicians provide comprehensive lab testing, medical examinations informed by the latest scientific research, and
evidence-based hormone therapy including SERMs, testosterone, HCG, and HGH to help you look and feel your best. Contact us today for a consultation and discover your best self through expert hormone balance and regeneration.
