# Semaglutide and Reproductive Hormones in Rats: A Pair-Fed Study | This GLP Semaglutide in diet-induced obese rats against pair-fed controls: androgens fell on food restriction and less on the drug, while female hormones fell in a treatment-specific way. Publisher: This GLP Editorial Team Canonical: https://thisglp.com/research/semaglutide-reproduction-pair-fed-rats Updated: 2026-09-18 Published: 2026-09-16 [← Research](https://thisglp.com/research) Evidence # Semaglutide and Reproductive Hormones in Rats: A Pair-Fed Study A second group of obese rats was fed exactly what the treated ones ate, so it lost the same weight without the drug. The gap between those two arms is the molecule. [This GLP Editorial Team](https://thisglp.com/about)September 20267 min readUpdated September 2026 Why a pair-fed arm exists · fed freely · no weight loss, no drug · pair-fed to match · same weight loss, no drug · semaglutide · same weight loss, plus drug · The difference between the last two rows is the drug itself. **Research, not medical advice.** This GLP is independent and educational. Nothing here is a substitute for individualized care from a licensed clinician, and reading it creates no doctor–patient relationship. Talk to your own provider before starting, stopping, or changing any medication, peptide, or therapy. See our [methodology](https://thisglp.com/methodology) and [terms](https://thisglp.com/terms). ## Key takeaways - Diet-induced obese rats, four weeks of semaglutide, with a pair-fed control group. - The pair-fed animals ate exactly what the treated ones ate, so they lost weight without the drug. - In males, weight loss lowered androgens and semaglutide blunted that reduction. - In females, progesterone, pregnenolone and estradiol fell in a way the diet alone did not produce. - GLP-1 receptor expression was four-fold higher in testes than in ovaries. These are rats — 4 weeks of treatment in diet-induced obese animals. Nothing below is a finding about a person, and 4 weeks in a rodent is not a year in a human being. What makes the study worth reading anyway is a control group most studies skip. [\[1\]](https://thisglp.com/research/semaglutide-reproduction-pair-fed-rats#ref-1) ## The arm that does the work Every question about these drugs runs into the same confound: the people taking them are also losing weight, and weight loss changes almost everything you might want to measure. A pair-fed control settles it. One group gets the drug; a second group is fed exactly the amount the first group chose to eat, so it loses the same weight with no drug in it. Anything that differs between those two arms is the molecule. Anything they share is the eating. That is the design human studies almost never manage, which is why so much of this field cannot separate the two — the same trouble behind [measurements taken on a shrinking body](https://thisglp.com/research/glp1-body-composition-smart-scale). ## What separated, and which way In male rats, both the drug and the matched restriction improved sperm motility and mucus penetration. That shared result points at the weight rather than the molecule. The hormones went the other way. Restriction lowered androgens, and semaglutide attenuated that fall — so here the drug partly offset something the weight loss caused. In females, progesterone, pregnenolone and estradiol fell in a treatment-specific way, meaning the diet alone did not do it. Folliculogenesis increased in both arms. Pituitary hormones shifted in both sexes. Two different kinds of finding A drug that blunts a weight-loss effect and a drug that causes an effect of its own are not the same discovery, and this study found one of each in different sexes. That is worth holding onto, because summaries will flatten it into “semaglutide affects reproductive hormones”, which is true of both and useful about neither. ## What the receptor count does and does not say GLP-1 receptor expression measured 4-fold higher in testes than in ovaries — a ratio of 4.0 between two tissues in the same animals. The authors describe this as supporting a potential male bias for the drug’s potency. Expression is not potency. A tissue can carry many receptors and respond little, or few and respond strongly, and this study did not test the link. Keep it as the hedge they wrote it as, the way [a marker close to the mechanism](https://thisglp.com/research/glp1-pcos-insulin-resistance) still has to be shown to move. ## What nobody measured Whether any animal conceived. The morphology is described as largely suggesting increased fertility, which is a statement about tissue under a microscope. In humans the direct evidence remains thin in both directions — small and narrow on the male side, as [a twenty-five-man comparison](https://thisglp.com/research/do-glp1-drugs-affect-fertility) shows, and almost absent for anything a rodent can only gesture at. Animal work of this quality tells you which human study to run. It does not substitute for one, any more than [ninety-two more days in mice](https://thisglp.com/research/semaglutide-lifespan-in-mice) settles anything about a lifespan. ## Frequently asked Does semaglutide affect fertility? This study was in rats and measured hormones and gonad structure, not conception. The findings differ by sex and cannot be read across to people. What is a pair-fed control? A group fed exactly the amount the treated group ate, so it loses the same weight without receiving the drug. Differences between the two arms are the drug; shared results are the eating. What differed between the sexes? In males the drug blunted a fall in androgens that weight loss caused. In females several hormones fell in a way calorie restriction alone did not produce. Does higher receptor expression mean a stronger effect? Not on its own. Testes carried four-fold more GLP-1 receptor than ovaries, but expression is not potency and this study did not test the link. ## Sources 1. \[1\] Sotzen MR, et al. (2026). Beyond weight loss: Disentangling the direct effects of semaglutide vs equivalent calorie restriction on reproductive systems of male and female rats Molecular Metabolism. [PMID 42692145](https://pubmed.ncbi.nlm.nih.gov/42692145/) ## Where to get it ### Best GLP-1 injections Every injectable seller we can verify, with the price each one publishes and an honest read of what the trials measured. 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