Nandrolone is converted to dihydro nandrolone by 5-alpha reductase, which has minimal androgenic activity, thus preserving anabolic properties in muscle while reducing hair loss in the scalp.

“it will five Al reduce into a DI hydron nandrolone which is almost no enic activity so in the muscle where you have a relative absence of 5 AR you will retain the anabolic properties of nandrolone where you want it but then in your scalp it'll 5 Alp reduce into this metabolite dihydro nandrolone where it has almost no adicity so you get like the muscle building without the hair loss”