Can't remember where I heard it-- some MD on a podcast recently-- but he mentioned distance running increases visceral fat in your muscles and around your organs when compared to HIIT and weight training, and visceral fat is generally a health risk indicator.

Visceral fat is fat around organs. It doesn't exist in muscles. I highly doubt that distance running increases visceral fat, that sounds made up. It may be that weight lifting is better for losing visceral fat, but that doesn't mean distance running is bad.