This is a link to a full JAMA article about the use of dutasteride in male subjects receiving TRT. The study demonstrates that there was no difference in lean body mass (LBM) bw the two groups. I was very surprised by these results as I thought low dose finasteride (Propecia) would decrease LBM. Dutasteride is significantly stronger as it inhibits both forms of 5-alpha reductase where finasteride only inhibits one, which only made the results more surprising to me. Just a note they used a tremendous dose, 2.5mg of dutasteride ed in this study. It's typical dosing for BPH is 0.5mg ed. Also they had 4 testosterone group levels with the highest level group receiving 600mg/wk. There was no difference in LBM at all 4 levels.

Interestingly, prostate volume and sexual function were unaffected by the addition of dutasteride as well.

One major drawback of the study as it pertains to ppl in this forum is that the subjects were not forced to exercise or perform resistance training which somewhat limits the application of this study to AAS use and resistance training.

All I can say that this study can offer a little more confidence to those who want to use finasteride or dutasteride on cycle but are worried about sexual problems and LBM gains.