In six weeks of high dose* fish oil, they gained a pound of muscle and lost a pound of fat.**
*1,600 mg/d eicosapentaenoic acid (EPA) and 800 mg/d docosahexaenoic acid (DHA)
** I could find no mention anywhere, that the study participants trained!!
https://www.ncbi.nlm.nih.gov/pubmed/20932294
The researchers put the increase in LBM down to a decrease in cortisol...