THE SIGNAL
There is no clear mechanism in the literature that says the peptide lowers libido. The signal has not been studied directly in a trial.
THE OVERLAPPING FACTORS
Libido is shaped by sleep, stress, hormones, body composition, body image, relationship context, other medications, and nutrition. Each of those moves during weight loss. Some shifts (lower visceral fat, better sleep, improved insulin signaling) tend to favor libido. Others (under-eating, micronutrient gaps, fatigue) push the other way.
THE NEAREST EVIDENCE
A 2024 systematic review on GLP-1 and reward-system pathways found the peptides affect motivation and craving, but the review covered food and substance use, not sexual function specifically.
What this means
"The peptide lowered my libido" almost always collapses several factors into one story. The evidence to support the simple version of the claim does not exist yet.
A sustained change deserves a workup, not a one-line attribution.
Libido does not have a clean on-off switch in this peptide class; it sits at the intersection of everything else that changes during weight loss.